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stb/stb_resample.h

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/* stb_resample - v0.50 - public domain image resampling
no warranty implied; use at your own risk
Do this:
#define STB_RESAMPLE_IMPLEMENTATION
before you include this file in *one* C or C++ file to create the implementation.
#define STBR_ASSERT(x) to avoid using assert.h.
#define STBR_NO_MALLOC to avoid using stdlib.h and malloc. This will remove
all resize functions except stbr_resize_arbitrary() from the API.
QUICK NOTES:
Written with emphasis on usage and speed. Only the resize operation is
currently supported, no rotations or translations.
Supports arbitrary resize for separable filters. For a list of
supported filters see the stbr_filter enum. To add a new filter,
write a filter function and add it to stbr__filter_info_table.
Latest revisions:
0.50 (2014-07-29) first released version
See end of file for full revision history.
TODO:
Installable filters
Specify with (s0, t0) X (s1, t1) what area of the source image to use,
at sub-pixel level
Specify wrap and filter modes independently for each axis
Resize that respects alpha test coverage
(Reference code: FloatImage::alphaTestCoverage and FloatImage::scaleAlphaToCoverage:
https://code.google.com/p/nvidia-texture-tools/source/browse/trunk/src/nvimage/FloatImage.cpp )
Initial implementation by Jorge L Rodriguez, @VinoBS
*/
#ifndef STBR_INCLUDE_STB_RESAMPLE_H
#define STBR_INCLUDE_STB_RESAMPLE_H
// Basic usage:
// result = stbr_resize_srgb_uint8(input_data, input_w, input_h, output_data, output_w, output_h, channels, STBR_FILTER_CATMULLROM, STBR_EDGE_CLAMP);
//
// input_data is your supplied texels.
// output_data will be the resized texels. It should be of size output_w * output_h * channels
// Returned result is 1 for success or 0 in case of an error. Currently the only error is failure to allocate memory.
// If you're unsure of which filter to use, Catmull-Rom is a good upsampling filter and Mitchell is a good downsampling filter.
// Advanced usage:
// size_t memory_required = stbr_calculate_memory(input_w, input_h, output_w, output_h, channels, STBR_FILTER_CATMULLROM);
// void* extra_memory = malloc(memory_required); // Any memory allocation method of your choosing
// result = stbr_resize_arbitrary(input_data, input_w, input_h, input_stride_in_bytes,
// output_data, output_w, output_h, output_stride_in_bytes,
// channels, STBR_TYPE_UINT8, STBR_FILTER_CATMULLROM, STBR_EDGE_CLAMP, STBR_COLORSPACE_SRGB,
// extra_memory, memory_required);
// free(extra_memory);
//
// input_stride_in_bytes and output_stride_in_bytes can be 0. If so they will be automatically calculated as width * channels.
// Returned result is 1 for success or 0 in case of an error. Currently the only error is that the memory passed in is insufficient.
// stbr_resize_arbitrary() will not allocate any memory, it will use the memory you pass in to do its work.
typedef enum
{
STBR_FILTER_NEAREST = 1,
STBR_FILTER_BILINEAR = 2,
STBR_FILTER_BICUBIC = 3, // A cubic b spline
STBR_FILTER_CATMULLROM = 4,
STBR_FILTER_MITCHELL = 5,
} stbr_filter;
typedef enum
{
STBR_EDGE_CLAMP = 1,
STBR_EDGE_REFLECT = 2,
STBR_EDGE_WRAP = 3,
} stbr_edge;
typedef enum
{
STBR_COLORSPACE_LINEAR = 1,
STBR_COLORSPACE_SRGB = 2,
// If you add here, update STBR_MAX_COLORSPACES
} stbr_colorspace;
#define STBR_MAX_COLORSPACES 2
typedef enum
{
STBR_TYPE_UINT8 = 1,
STBR_TYPE_UINT16 = 2,
STBR_TYPE_UINT32 = 3,
STBR_TYPE_FLOAT = 4,
// If you add here, update STBR_MAX_TYPES
} stbr_type;
#define STBR_MAX_TYPES 4
typedef unsigned char stbr_uint8;
#ifdef _MSC_VER
typedef unsigned short stbr_uint16;
typedef unsigned int stbr_uint32;
#else
#include <stdint.h>
typedef uint16_t stbr_uint16;
typedef uint32_t stbr_uint32;
#endif
typedef unsigned int stbr_size_t; // to avoid including a header for size_t
#ifdef __cplusplus
extern "C" {
#endif
#ifdef STB_RESAMPLE_STATIC
#define STBRDEF static
#else
#define STBRDEF extern
#endif
#ifndef STBR_NO_MALLOC
//////////////////////////////////////////////////////////////////////////////
//
// PRIMARY API - sRGB type-safe image resizing.
//
STBRDEF int stbr_resize_srgb_uint8(const stbr_uint8* input_data, int input_w, int input_h,
stbr_uint8* output_data, int output_w, int output_h,
int channels, stbr_filter filter, stbr_edge edge);
STBRDEF int stbr_resize_srgb_uint16(const stbr_uint16* input_data, int input_w, int input_h,
stbr_uint16* output_data, int output_w, int output_h,
int channels, stbr_filter filter, stbr_edge edge);
STBRDEF int stbr_resize_srgb_uint32(const stbr_uint32* input_data, int input_w, int input_h,
stbr_uint32* output_data, int output_w, int output_h,
int channels, stbr_filter filter, stbr_edge edge);
STBRDEF int stbr_resize_srgb_float(const float* input_data, int input_w, int input_h,
float* output_data, int output_w, int output_h,
int channels, stbr_filter filter, stbr_edge edge);
#endif // STBR_NO_MALLOC
//////////////////////////////////////////////////////////////////////////////
//
// ADVANCED API
//
STBRDEF stbr_size_t stbr_calculate_memory(int input_w, int input_h, int output_w, int output_h, int channels, stbr_filter filter);
STBRDEF int stbr_resize_arbitrary(const void* input_data, int input_w, int input_h, int input_stride_in_bytes,
void* output_data, int output_w, int output_h, int output_stride_in_bytes,
int channels, stbr_type type, stbr_filter filter, stbr_edge edge, stbr_colorspace colorspace,
void* tempmem, stbr_size_t tempmem_size_in_bytes);
#ifdef __cplusplus
}
#endif
//
//
//// end header file /////////////////////////////////////////////////////
#endif // STBR_INCLUDE_STB_RESAMPLE_H
#ifdef STB_RESIZE_IMPLEMENTATION
#ifndef STBR_ASSERT
#include <assert.h>
#define STBR_ASSERT(x) assert(x)
#endif
#ifdef STBR_DEBUG
#define STBR_DEBUG_ASSERT STBR_ASSERT
#else
#define STBR_DEBUG_ASSERT
#endif
// If you hit this it means I haven't done it yet.
#define STBR_UNIMPLEMENTED(x) STBR_ASSERT(!(x))
// For memset
#include <string.h>
#include <math.h>
#ifndef STBR_NO_MALLOC
#include <stdlib.h>
#endif
#ifndef _MSC_VER
#ifdef __cplusplus
#define stbr_inline inline
#else
#define stbr_inline
#endif
#else
#define stbr_inline __forceinline
#endif
// should produce compiler error if size is wrong
typedef unsigned char stbr__validate_uint32[sizeof(stbr_uint32) == 4 ? 1 : -1];
#ifdef _MSC_VER
#define STBR_NOTUSED(v) (void)(v)
#else
#define STBR_NOTUSED(v) (void)sizeof(v)
#endif
#define STBR_ARRAY_SIZE(a) (sizeof((a))/sizeof((a)[0]))
#define STBR__MAX_UNROLLED_CHANNELS 4
// Kernel function centered at 0
typedef float (stbr__kernel_fn)(float x);
typedef struct
{
stbr__kernel_fn* kernel;
float support;
} stbr__filter_info;
// When upsampling, the contributors are which source texels contribute.
// When downsampling, the contributors are which destination texels are contributed to.
typedef struct
{
int n0; // First contributing texel
int n1; // Last contributing texel
} stbr__contributors;
typedef struct
{
const void* input_data;
int input_w;
int input_h;
int input_stride_bytes;
void* output_data;
int output_w;
int output_h;
int output_stride_bytes;
int channels;
stbr_type type;
stbr_filter filter;
stbr_edge edge;
stbr_colorspace colorspace;
stbr__contributors* horizontal_contributors;
float* horizontal_coefficients;
stbr__contributors vertical_contributors;
float* vertical_coefficients;
int decode_buffer_texels;
float* decode_buffer;
float* horizontal_buffer;
int ring_buffer_length_bytes; // The length of an individual entry in the ring buffer. The total number of ring buffers is stbr__get_filter_texel_width(filter)
int ring_buffer_first_scanline;
int ring_buffer_last_scanline;
int ring_buffer_begin_index;
float* ring_buffer;
float* encode_buffer; // A temporary buffer to store floats so we don't lose precision while we do multiply-adds.
} stbr__info;
static stbr_inline int stbr__min(int a, int b)
{
return a < b ? a : b;
}
static stbr_inline int stbr__max(int a, int b)
{
return a > b ? a : b;
}
static stbr_inline float stbr__saturate(float x)
{
if (x < 0)
return 0;
if (x > 1)
return 1;
return x;
}
static float stbr__srgb_uchar_to_linear_float[256] = {
0.000000f, 0.000304f, 0.000607f, 0.000911f, 0.001214f, 0.001518f, 0.001821f, 0.002125f, 0.002428f, 0.002732f, 0.003035f, 0.003347f, 0.003677f, 0.004025f, 0.004391f, 0.004777f, 0.005182f, 0.005605f, 0.006049f, 0.006512f, 0.006995f, 0.007499f, 0.008023f, 0.008568f, 0.009134f, 0.009721f, 0.010330f, 0.010960f, 0.011612f, 0.012286f, 0.012983f, 0.013702f, 0.014444f, 0.015209f, 0.015996f, 0.016807f, 0.017642f, 0.018500f, 0.019382f, 0.020289f, 0.021219f, 0.022174f, 0.023153f, 0.024158f, 0.025187f, 0.026241f, 0.027321f, 0.028426f, 0.029557f, 0.030713f, 0.031896f, 0.033105f, 0.034340f, 0.035601f, 0.036889f, 0.038204f, 0.039546f, 0.040915f, 0.042311f, 0.043735f, 0.045186f, 0.046665f, 0.048172f, 0.049707f, 0.051269f, 0.052861f, 0.054480f, 0.056128f, 0.057805f, 0.059511f, 0.061246f, 0.063010f, 0.064803f, 0.066626f, 0.068478f, 0.070360f, 0.072272f, 0.074214f, 0.076185f, 0.078187f, 0.080220f, 0.082283f, 0.084376f, 0.086500f, 0.088656f, 0.090842f, 0.093059f, 0.095307f, 0.097587f, 0.099899f, 0.102242f, 0.104616f, 0.107023f, 0.109462f, 0.111932f, 0.114435f, 0.116971f, 0.119538f, 0.122139f, 0.124772f, 0.127438f, 0.130136f, 0.132868f, 0.135633f, 0.138432f, 0.141263f, 0.144128f, 0.147027f, 0.149960f, 0.152926f, 0.155926f, 0.158961f, 0.162029f, 0.165132f, 0.168269f, 0.171441f, 0.174647f, 0.177888f, 0.181164f, 0.184475f, 0.187821f, 0.191202f, 0.194618f, 0.198069f, 0.201556f, 0.205079f, 0.208637f, 0.212231f, 0.215861f, 0.219526f, 0.223228f, 0.226966f, 0.230740f, 0.234551f, 0.238398f, 0.242281f, 0.246201f, 0.250158f, 0.254152f, 0.258183f, 0.262251f, 0.266356f, 0.270498f, 0.274677f, 0.278894f, 0.283149f, 0.287441f, 0.291771f, 0.296138f, 0.300544f, 0.304987f, 0.309469f, 0.313989f, 0.318547f, 0.323143f, 0.327778f, 0.332452f, 0.337164f, 0.341914f, 0.346704f, 0.351533f, 0.356400f, 0.361307f, 0.366253f, 0.371238f, 0.376262f, 0.381326f, 0.386430f, 0.391573f, 0.396755f, 0.401978f, 0.407240f, 0.412543f, 0.417885f, 0.423268f, 0.428691f, 0.434154f, 0.439657f, 0.445201f, 0.450786f, 0.456411f, 0.462077f, 0.467784f, 0.473532f, 0.479320f, 0.485150f, 0.491021f, 0.496933f, 0.502887f, 0.508881f, 0.514918f, 0.520996f, 0.527115f, 0.533276f, 0.539480f, 0.545725f, 0.552011f, 0.558340f, 0.564712f, 0.571125f, 0.577581f, 0.584078f, 0.590619f, 0.597202f, 0.603827f, 0.610496f, 0.617207f, 0.623960f, 0.630757f, 0.637597f, 0.644480f, 0.651406f, 0.658375f, 0.665387f, 0.672443f, 0.679543f, 0.686685f, 0.693872f, 0.701102f, 0.708376f, 0.715694f, 0.723055f, 0.730461f, 0.737911f, 0.745404f, 0.752942f, 0.760525f, 0.768151f, 0.775822f, 0.783538f, 0.791298f, 0.799103f, 0.806952f, 0.814847f, 0.822786f, 0.830770f, 0.838799f, 0.846873f, 0.854993f, 0.863157f, 0.871367f, 0.879622f, 0.887923f, 0.896269f, 0.904661f, 0.913099f, 0.921582f, 0.930111f, 0.938686f, 0.947307f, 0.955974f, 0.964686f, 0.973445f, 0.982251f, 0.991102f, 1.0f
};
static unsigned char stbr__linear_uchar_to_srgb_uchar[256] = {
0, 12, 21, 28, 33, 38, 42, 46, 49, 52, 55, 58, 61, 63, 66, 68, 70, 73, 75, 77, 79, 81, 82, 84, 86, 88, 89, 91, 93, 94, 96, 97, 99, 100, 102, 103, 104, 106, 107, 109, 110, 111, 112, 114, 115, 116, 117, 118, 120, 121, 122, 123, 124, 125, 126, 127, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 151, 152, 153, 154, 155, 156, 157, 157, 158, 159, 160, 161, 161, 162, 163, 164, 165, 165, 166, 167, 168, 168, 169, 170, 171, 171, 172, 173, 174, 174, 175, 176, 176, 177, 178, 179, 179, 180, 181, 181, 182, 183, 183, 184, 185, 185, 186, 187, 187, 188, 189, 189, 190, 191, 191, 192, 193, 193, 194, 194, 195, 196, 196, 197, 197, 198, 199, 199, 200, 201, 201, 202, 202, 203, 204, 204, 205, 205, 206, 206, 207, 208, 208, 209, 209, 210, 210, 211, 212, 212, 213, 213, 214, 214, 215, 215, 216, 217, 217, 218, 218, 219, 219, 220, 220, 221, 221, 222, 222, 223, 223, 224, 224, 225, 226, 226, 227, 227, 228, 228, 229, 229, 230, 230, 231, 231, 232, 232, 233, 233, 234, 234, 235, 235, 236, 236, 237, 237, 237, 238, 238, 239, 239, 240, 240, 241, 241, 242, 242, 243, 243, 244, 244, 245, 245, 245, 246, 246, 247, 247, 248, 248, 249, 249, 250, 250, 251, 251, 251, 252, 252, 253, 253, 254, 254, 255
};
float stbr__srgb_to_linear(float f)
{
if (f <= 0.04045f)
return f / 12.92f;
else
return (float)pow((f + 0.055f) / 1.055f, 2.4f);
}
float stbr__linear_to_srgb(float f)
{
if (f <= 0.0031308f)
return f * 12.92f;
else
return 1.055f * (float)pow(f, 1 / 2.4f) - 0.055f;
}
static float stbr__filter_nearest(float x)
{
x = (float)fabs(x);
if (x <= 0.5)
return 1;
else
return 0;
}
static float stbr__filter_bilinear(float x)
{
x = (float)fabs(x);
if (x <= 1.0f)
return 1 - x;
else
return 0;
}
static float stbr__filter_bicubic(float x)
{
x = (float)fabs(x);
if (x < 1.0f)
return 0.66666666666f + x*x*(0.5f*x - 1);
else if (x < 2.0f)
return 1.3333333333f + x*(-2 + x*(1 - 0.16666666f * x));
return (0.0f);
}
static float stbr__filter_catmullrom(float x)
{
x = (float)fabs(x);
if (x < 1.0f)
return 1 - x*x*(2.5f - 1.5f*x);
else if (x < 2.0f)
return 2 - x*(4 + x*(0.5f*x - 2.5f));
return (0.0f);
}
static float stbr__filter_mitchell(float x)
{
x = (float)fabs(x);
if (x < 1.0f)
return 0.8888888888f + x*x*(1.1666666666666f * x - 2.0f);
else if (x < 2.0f)
return 1.777777777777f + x*(-3.3333333333f + x*(2 - 0.3888888888888f*x));
return (0.0f);
}
static stbr__filter_info stbr__filter_info_table[] = {
{ NULL, 0.0f },
{ stbr__filter_nearest, 0.5f },
{ stbr__filter_bilinear, 1.0f },
{ stbr__filter_bicubic, 2.0f },
{ stbr__filter_catmullrom, 2.0f },
{ stbr__filter_mitchell, 2.0f },
};
stbr_inline static int stbr__use_width_upsampling_noinfo(int output_w, int input_w)
{
return output_w > input_w;
}
stbr_inline static int stbr__use_height_upsampling_noinfo(int output_h, int input_h)
{
return output_h > input_h;
}
stbr_inline static int stbr__use_width_upsampling(stbr__info* stbr_info)
{
return stbr__use_width_upsampling_noinfo(stbr_info->output_w, stbr_info->input_w);
}
stbr_inline static int stbr__use_height_upsampling(stbr__info* stbr_info)
{
return stbr__use_height_upsampling_noinfo(stbr_info->output_h, stbr_info->input_h);
}
// This is the maximum number of input samples that can affect an output sample
// with the given filter
stbr_inline static int stbr__get_filter_texel_width(stbr_filter filter, int input_w, int output_w)
{
STBR_ASSERT(filter != 0);
STBR_ASSERT(filter < STBR_ARRAY_SIZE(stbr__filter_info_table));
if (stbr__use_height_upsampling_noinfo(output_w, input_w))
return (int)ceil(stbr__filter_info_table[filter].support * 2);
else
return (int)ceil(stbr__filter_info_table[filter].support * 2 * input_w / output_w);
}
// This is how much to expand buffers to account for filters seeking outside
// the image boundaries.
stbr_inline static int stbr__get_filter_texel_margin(stbr_filter filter, int input_w, int output_w)
{
return stbr__get_filter_texel_width(filter, input_w, output_w) / 2;
}
stbr_inline static int stbr__get_horizontal_contributors(stbr_filter filter, int input_w, int output_w)
{
if (stbr__use_width_upsampling_noinfo(output_w, input_w))
return output_w;
else
return (input_w + stbr__get_filter_texel_margin(filter, input_w, output_w) * 2);
}
stbr_inline static int stbr__get_total_coefficients(stbr_filter filter, int input_w, int output_w)
{
return stbr__get_horizontal_contributors(filter, input_w, output_w) * stbr__get_filter_texel_width(filter, input_w, output_w);
}
stbr_inline static stbr__contributors* stbr__get_contributor(stbr__info* stbr_info, int n)
{
STBR_DEBUG_ASSERT(n >= 0 && n < stbr__get_horizontal_contributors(stbr_info->filter, stbr_info->input_w, stbr_info->output_w));
return &stbr_info->horizontal_contributors[n];
}
stbr_inline static float* stbr__get_coefficient(stbr__info* stbr_info, int n, int c)
{
return &stbr_info->horizontal_coefficients[stbr__get_filter_texel_width(stbr_info->filter, stbr_info->input_w, stbr_info->output_w)*n + c];
}
stbr_inline static int stbr__edge_wrap(stbr_edge edge, int n, int max)
{
switch (edge)
{
case STBR_EDGE_CLAMP:
if (n < 0)
return 0;
if (n >= max)
return max - 1;
return n;
case STBR_EDGE_REFLECT:
{
if (n < 0)
{
if (n < max)
return -n;
else
return max - 1;
}
if (n >= max)
{
int max2 = max * 2;
if (n >= max2)
return 0;
else
return max2 - n - 1;
}
return n;
}
case STBR_EDGE_WRAP:
if (n >= 0)
return (n % max);
else
{
int m = (-n) % max;
if (m != 0)
m = max - m;
return (m);
}
default:
STBR_UNIMPLEMENTED("Unimplemented edge type");
return 0;
}
}
// What input texels contribute to this output texel?
static void stbr__calculate_sample_range_upsample(int n, float out_filter_radius, float scale_ratio, int* in_first_texel, int* in_last_texel, float* in_center_of_out)
{
float out_texel_center = (float)n + 0.5f;
float out_texel_influence_lowerbound = out_texel_center - out_filter_radius;
float out_texel_influence_upperbound = out_texel_center + out_filter_radius;
float in_texel_influence_lowerbound = out_texel_influence_lowerbound / scale_ratio;
float in_texel_influence_upperbound = out_texel_influence_upperbound / scale_ratio;
*in_center_of_out = out_texel_center / scale_ratio;
*in_first_texel = (int)(floor(in_texel_influence_lowerbound + 0.5));
*in_last_texel = (int)(floor(in_texel_influence_upperbound - 0.5));
}
// What output texels does this input texel contribute to?
static void stbr__calculate_sample_range_downsample(int n, float in_pixels_radius, float scale_ratio, int* out_first_texel, int* out_last_texel, float* out_center_of_in)
{
float in_texel_center = (float)n + 0.5f;
float in_texel_influence_lowerbound = in_texel_center - in_pixels_radius;
float in_texel_influence_upperbound = in_texel_center + in_pixels_radius;
float out_texel_influence_lowerbound = in_texel_influence_lowerbound * scale_ratio;
float out_texel_influence_upperbound = in_texel_influence_upperbound * scale_ratio;
*out_center_of_in = in_texel_center * scale_ratio;
*out_first_texel = (int)(floor(out_texel_influence_lowerbound + 0.5));
*out_last_texel = (int)(floor(out_texel_influence_upperbound - 0.5));
}
static void stbr__calculate_coefficients_upsample(stbr__info* stbr_info, int in_first_texel, int in_last_texel, float in_center_of_out, stbr__contributors* contributor, float* coefficient_group)
{
int i;
float total_filter = 0;
float filter_scale;
stbr_filter filter = stbr_info->filter;
STBR_DEBUG_ASSERT(in_last_texel - in_first_texel <= stbr__get_filter_texel_width(filter, stbr_info->input_w, stbr_info->output_w));
STBR_DEBUG_ASSERT(in_last_texel < stbr__get_horizontal_contributors(stbr_info->filter, stbr_info->input_w, stbr_info->output_w));
contributor->n0 = in_first_texel;
contributor->n1 = in_last_texel;
STBR_DEBUG_ASSERT(contributor->n1 >= contributor->n0);
for (i = 0; i <= in_last_texel - in_first_texel; i++)
{
float in_texel_center = (float)(i + in_first_texel) + 0.5f;
total_filter += coefficient_group[i] = stbr__filter_info_table[filter].kernel(in_center_of_out - in_texel_center);
}
STBR_DEBUG_ASSERT(total_filter > 0.9);
STBR_DEBUG_ASSERT(total_filter < 1.1f); // Make sure it's not way off.
// Make sure the sum of all coefficients is 1.
filter_scale = 1 / total_filter;
for (i = 0; i <= in_last_texel - in_first_texel; i++)
coefficient_group[i] *= filter_scale;
}
static void stbr__calculate_coefficients_downsample(stbr__info* stbr_info, float scale_ratio, int out_first_texel, int out_last_texel, float out_center_of_in, stbr__contributors* contributor, float* coefficient_group)
{
int i;
stbr_filter filter = stbr_info->filter;
STBR_DEBUG_ASSERT(out_last_texel - out_first_texel <= stbr__get_filter_texel_width(filter, stbr_info->input_w, stbr_info->output_w));
STBR_DEBUG_ASSERT(out_last_texel < stbr__get_horizontal_contributors(stbr_info->filter, stbr_info->input_w, stbr_info->output_w));
contributor->n0 = out_first_texel;
contributor->n1 = out_last_texel;
STBR_DEBUG_ASSERT(contributor->n1 >= contributor->n0);
for (i = 0; i <= out_last_texel - out_first_texel; i++)
{
float in_texel_center = (float)(i + out_first_texel) + 0.5f;
coefficient_group[i] = stbr__filter_info_table[filter].kernel((out_center_of_in - in_texel_center)/scale_ratio);
}
}
#ifdef STBR_DEBUG
static void stbr__check_downsample_coefficients(stbr__info* stbr_info)
{
for (int i = 0; i < stbr_info->output_w; i++)
{
float total = 0;
for (int j = 0; j < stbr__get_horizontal_contributors(stbr_info->filter, stbr_info->input_w, stbr_info->output_w); j++)
{
if (i >= stbr_info->horizontal_contributors[j].n0 && i <= stbr_info->horizontal_contributors[j].n1)
{
float coefficient = *stbr__get_coefficient(stbr_info, j, i - stbr_info->horizontal_contributors[j].n0);
total += coefficient;
}
else if (i < stbr_info->horizontal_contributors[j].n0)
break;
}
STBR_DEBUG_ASSERT(stbr_info->type == STBR_TYPE_UINT8); // Assert below should be 1 + 1/(2^n-1) where n is bits per int.
STBR_DEBUG_ASSERT(total > 0.9f);
STBR_DEBUG_ASSERT(total <= 1.0f + 1.0f / 255);
}
}
#endif
// Each scan line uses the same kernel values so we should calculate the kernel
// values once and then we can use them for every scan line.
static void stbr__calculate_horizontal_filters(stbr__info* stbr_info)
{
int n;
float scale_ratio = (float)stbr_info->output_w / stbr_info->input_w;
int total_contributors = stbr__get_horizontal_contributors(stbr_info->filter, stbr_info->input_w, stbr_info->output_w);
if (stbr__use_width_upsampling(stbr_info))
{
float out_pixels_radius = stbr__filter_info_table[stbr_info->filter].support * scale_ratio;
// Looping through out texels
for (n = 0; n < total_contributors; n++)
{
float in_center_of_out; // Center of the current out texel in the in texel space
int in_first_texel, in_last_texel;
stbr__calculate_sample_range_upsample(n, out_pixels_radius, scale_ratio, &in_first_texel, &in_last_texel, &in_center_of_out);
stbr__calculate_coefficients_upsample(stbr_info, in_first_texel, in_last_texel, in_center_of_out, stbr__get_contributor(stbr_info, n), stbr__get_coefficient(stbr_info, n, 0));
}
}
else
{
float in_pixels_radius = stbr__filter_info_table[stbr_info->filter].support / scale_ratio;
// Looping through in texels
for (n = 0; n < total_contributors; n++)
{
float out_center_of_in; // Center of the current out texel in the in texel space
int out_first_texel, out_last_texel;
int n_adjusted = n - stbr__get_filter_texel_margin(stbr_info->filter, stbr_info->input_w, stbr_info->output_w);
stbr__calculate_sample_range_downsample(n_adjusted, in_pixels_radius, scale_ratio, &out_first_texel, &out_last_texel, &out_center_of_in);
stbr__calculate_coefficients_downsample(stbr_info, scale_ratio, out_first_texel, out_last_texel, out_center_of_in, stbr__get_contributor(stbr_info, n), stbr__get_coefficient(stbr_info, n, 0));
}
#ifdef STBR_DEBUG
stbr__check_downsample_coefficients(stbr_info);
#endif
}
}
static float* stbr__get_decode_buffer(stbr__info* stbr_info)
{
// The 0 index of the decode buffer starts after the margin. This makes
// it okay to use negative indexes on the decode buffer.
return &stbr_info->decode_buffer[stbr__get_filter_texel_margin(stbr_info->filter, stbr_info->input_w, stbr_info->output_w) * stbr_info->channels];
}
#define STBR__DECODE(type, colorspace) ((type) * (STBR_MAX_COLORSPACES) + (colorspace))
static void stbr__decode_scanline(stbr__info* stbr_info, int n)
{
int x;
int channels = stbr_info->channels;
int type = stbr_info->type;
int colorspace = stbr_info->colorspace;
int input_w = stbr_info->input_w;
int input_stride_bytes = stbr_info->input_stride_bytes;
const void* input_data = stbr_info->input_data;
float* decode_buffer = stbr__get_decode_buffer(stbr_info);
stbr_edge edge = stbr_info->edge;
int in_buffer_row_index = stbr__edge_wrap(edge, n, stbr_info->input_h) * input_stride_bytes;
int max_x = input_w + stbr__get_filter_texel_margin(stbr_info->filter, stbr_info->input_w, stbr_info->output_w);
int decode = STBR__DECODE(type, colorspace);
for (x = -stbr__get_filter_texel_margin(stbr_info->filter, stbr_info->input_w, stbr_info->output_w); x < max_x; x++)
{
int decode_texel_index = x * channels;
int input_texel_index = in_buffer_row_index + stbr__edge_wrap(edge, x, input_w) * channels;
switch (decode)
{
case STBR__DECODE(STBR_TYPE_UINT8, STBR_COLORSPACE_LINEAR):
for (int n = 0; n < channels; n++)
decode_buffer[decode_texel_index + n] = ((float)((const unsigned char*)input_data)[input_texel_index + n]) / 255;
break;
case STBR__DECODE(STBR_TYPE_UINT8, STBR_COLORSPACE_SRGB):
for (int n = 0; n < channels; n++)
decode_buffer[decode_texel_index + n] = stbr__srgb_uchar_to_linear_float[((const unsigned char*)input_data)[input_texel_index + n]];
break;
case STBR__DECODE(STBR_TYPE_UINT16, STBR_COLORSPACE_LINEAR):
for (int n = 0; n < channels; n++)
decode_buffer[decode_texel_index + n] = ((float)((const unsigned short*)input_data)[input_texel_index + n]) / 65535;
break;
case STBR__DECODE(STBR_TYPE_UINT16, STBR_COLORSPACE_SRGB):
for (int n = 0; n < channels; n++)
decode_buffer[decode_texel_index + n] = stbr__srgb_to_linear(((float)((const unsigned short*)input_data)[input_texel_index + n]) / 65535);
break;
case STBR__DECODE(STBR_TYPE_UINT32, STBR_COLORSPACE_LINEAR):
for (int n = 0; n < channels; n++)
decode_buffer[decode_texel_index + n] = ((float)((const unsigned int*)input_data)[input_texel_index + n]) / 4294967295;
break;
case STBR__DECODE(STBR_TYPE_UINT32, STBR_COLORSPACE_SRGB):
for (int n = 0; n < channels; n++)
decode_buffer[decode_texel_index + n] = stbr__srgb_to_linear(((float)((const unsigned int*)input_data)[input_texel_index + n]) / 4294967295);
break;
case STBR__DECODE(STBR_TYPE_FLOAT, STBR_COLORSPACE_LINEAR):
for (int n = 0; n < channels; n++)
decode_buffer[decode_texel_index + n] = ((const float*)input_data)[input_texel_index + n];
break;
case STBR__DECODE(STBR_TYPE_FLOAT, STBR_COLORSPACE_SRGB):
for (int n = 0; n < channels; n++)
decode_buffer[decode_texel_index + n] = stbr__srgb_to_linear(((const float*)input_data)[input_texel_index + n]);
break;
default:
STBR_UNIMPLEMENTED("Unknown type/colorspace/channels combination.");
break;
}
}
}
static float* stbr__get_ring_buffer_entry(float* ring_buffer, int index, int ring_buffer_length)
{
return &ring_buffer[index * ring_buffer_length];
}
static float* stbr__add_empty_ring_buffer_entry(stbr__info* stbr_info, int n)
{
int ring_buffer_index;
float* ring_buffer;
if (stbr_info->ring_buffer_begin_index < 0)
{
ring_buffer_index = stbr_info->ring_buffer_begin_index = 0;
stbr_info->ring_buffer_first_scanline = n;
}
else
{
ring_buffer_index = (stbr_info->ring_buffer_begin_index + (stbr_info->ring_buffer_last_scanline - stbr_info->ring_buffer_first_scanline) + 1) % stbr__get_filter_texel_width(stbr_info->filter, stbr_info->input_h, stbr_info->output_h);
STBR_DEBUG_ASSERT(ring_buffer_index != stbr_info->ring_buffer_begin_index);
}
ring_buffer = stbr__get_ring_buffer_entry(stbr_info->ring_buffer, ring_buffer_index, stbr_info->ring_buffer_length_bytes / sizeof(float));
memset(ring_buffer, 0, stbr_info->ring_buffer_length_bytes);
stbr_info->ring_buffer_last_scanline = n;
return ring_buffer;
}
static void stbr__resample_horizontal_upsample(stbr__info* stbr_info, int n, float* output_buffer)
{
int x, k;
int output_w = stbr_info->output_w;
int kernel_texel_width = stbr__get_filter_texel_width(stbr_info->filter, stbr_info->input_w, stbr_info->output_w);
int channels = stbr_info->channels;
float* decode_buffer = stbr__get_decode_buffer(stbr_info);
stbr__contributors* horizontal_contributors = stbr_info->horizontal_contributors;
float* horizontal_coefficients = stbr_info->horizontal_coefficients;
for (x = 0; x < output_w; x++)
{
int n0 = horizontal_contributors[x].n0;
int n1 = horizontal_contributors[x].n1;
int out_texel_index = x * channels;
int coefficient_group_index = x * kernel_texel_width;
int coefficient_counter = 0;
STBR_DEBUG_ASSERT(n1 >= n0);
STBR_DEBUG_ASSERT(n0 >= -stbr__get_filter_texel_margin(stbr_info->filter, stbr_info->input_w, stbr_info->output_w));
STBR_DEBUG_ASSERT(n1 >= -stbr__get_filter_texel_margin(stbr_info->filter, stbr_info->input_w, stbr_info->output_w));
STBR_DEBUG_ASSERT(n0 < stbr_info->input_w + stbr__get_filter_texel_margin(stbr_info->filter, stbr_info->input_w, stbr_info->output_w));
STBR_DEBUG_ASSERT(n1 < stbr_info->input_w + stbr__get_filter_texel_margin(stbr_info->filter, stbr_info->input_w, stbr_info->output_w));
for (k = n0; k <= n1; k++)
{
int coefficient_index = coefficient_group_index + (coefficient_counter++);
int in_texel_index = k * channels;
float coefficient = horizontal_coefficients[coefficient_index];
int c;
for (c = 0; c < channels; c++)
output_buffer[out_texel_index + c] += decode_buffer[in_texel_index + c] * coefficient;
}
}
}
static void stbr__resample_horizontal_downsample(stbr__info* stbr_info, int n, float* output_buffer)
{
int x, k;
int input_w = stbr_info->input_w;
int output_w = stbr_info->output_w;
int kernel_texel_width = stbr__get_filter_texel_width(stbr_info->filter, stbr_info->input_w, stbr_info->output_w);
int channels = stbr_info->channels;
float* decode_buffer = stbr__get_decode_buffer(stbr_info);
stbr__contributors* horizontal_contributors = stbr_info->horizontal_contributors;
float* horizontal_coefficients = stbr_info->horizontal_coefficients;
int filter_texel_margin = stbr__get_filter_texel_margin(stbr_info->filter, stbr_info->input_w, stbr_info->output_w);
int max_x = input_w + filter_texel_margin * 2;
STBR_DEBUG_ASSERT(!stbr__use_width_upsampling(stbr_info));
for (x = 0; x < max_x; x++)
{
int n0 = horizontal_contributors[x].n0;
int n1 = horizontal_contributors[x].n1;
int in_x = x - filter_texel_margin;
int in_texel_index = in_x * channels;
int max_n = stbr__min(n1, output_w-1);
int coefficient_group = x*kernel_texel_width;
STBR_DEBUG_ASSERT(n1 >= n0);
// Using min and max to avoid writing into invalid texels.
for (k = stbr__max(n0, 0); k <= max_n; k++)
{
int coefficient_index = (k - n0) + coefficient_group;
int out_texel_index = k * channels;
float coefficient = horizontal_coefficients[coefficient_index];
int c;
for (c = 0; c < channels; c++)
output_buffer[out_texel_index + c] += decode_buffer[in_texel_index + c] * coefficient;
}
}
}
static void stbr__decode_and_resample_upsample(stbr__info* stbr_info, int n)
{
// Decode the nth scanline from the source image into the decode buffer.
stbr__decode_scanline(stbr_info, n);
// Now resample it into the ring buffer.
if (stbr__use_width_upsampling(stbr_info))
stbr__resample_horizontal_upsample(stbr_info, n, stbr__add_empty_ring_buffer_entry(stbr_info, n));
else
stbr__resample_horizontal_downsample(stbr_info, n, stbr__add_empty_ring_buffer_entry(stbr_info, n));
// Now it's sitting in the ring buffer ready to be used as source for the vertical sampling.
}
static void stbr__decode_and_resample_downsample(stbr__info* stbr_info, int n)
{
// Decode the nth scanline from the source image into the decode buffer.
stbr__decode_scanline(stbr_info, n);
memset(stbr_info->horizontal_buffer, 0, stbr_info->output_w * stbr_info->channels * sizeof(float));
// Now resample it into the horizontal buffer.
if (stbr__use_width_upsampling(stbr_info))
stbr__resample_horizontal_upsample(stbr_info, n, stbr_info->horizontal_buffer);
else
stbr__resample_horizontal_downsample(stbr_info, n, stbr_info->horizontal_buffer);
// Now it's sitting in the horizontal buffer ready to be distributed into the ring buffers.
}
// Get the specified scan line from the ring buffer.
static float* stbr__get_ring_buffer_scanline(int get_scanline, float* ring_buffer, int begin_index, int first_scanline, int ring_buffer_size, int ring_buffer_length)
{
int ring_buffer_index = (begin_index + (get_scanline - first_scanline)) % ring_buffer_size;
return stbr__get_ring_buffer_entry(ring_buffer, ring_buffer_index, ring_buffer_length);
}
static stbr_inline void stbr__encode_scanline(void* output_buffer, int output_texel_index, float* encode_buffer, int encode_texel_index, int channels, int decode)
{
switch (decode)
{
case STBR__DECODE(STBR_TYPE_UINT8, STBR_COLORSPACE_LINEAR):
for (int n = 0; n < channels; n++)
((unsigned char*)output_buffer)[output_texel_index + n] = (unsigned char)(stbr__saturate(encode_buffer[encode_texel_index + n]) * 255);
break;
case STBR__DECODE(STBR_TYPE_UINT8, STBR_COLORSPACE_SRGB):
for (int n = 0; n < channels; n++)
((unsigned char*)output_buffer)[output_texel_index + n] = stbr__linear_uchar_to_srgb_uchar[(unsigned char)(stbr__saturate(encode_buffer[encode_texel_index + n]) * 255)];
break;
case STBR__DECODE(STBR_TYPE_UINT16, STBR_COLORSPACE_LINEAR):
for (int n = 0; n < channels; n++)
((unsigned short*)output_buffer)[output_texel_index + n] = (unsigned short)(stbr__saturate(encode_buffer[encode_texel_index + n]) * 65535);
break;
case STBR__DECODE(STBR_TYPE_UINT16, STBR_COLORSPACE_SRGB):
for (int n = 0; n < channels; n++)
((unsigned short*)output_buffer)[output_texel_index + n] = (unsigned short)stbr__linear_to_srgb((stbr__saturate(encode_buffer[encode_texel_index + n]) * 65535));
break;
case STBR__DECODE(STBR_TYPE_UINT32, STBR_COLORSPACE_LINEAR):
for (int n = 0; n < channels; n++)
((unsigned int*)output_buffer)[output_texel_index + n] = (unsigned int)(stbr__saturate(encode_buffer[encode_texel_index + n]) * 4294967295);
break;
case STBR__DECODE(STBR_TYPE_UINT32, STBR_COLORSPACE_SRGB):
for (int n = 0; n < channels; n++)
((unsigned int*)output_buffer)[output_texel_index + n] = (unsigned int)stbr__linear_to_srgb((stbr__saturate(encode_buffer[encode_texel_index + n]) * 4294967295));
break;
case STBR__DECODE(STBR_TYPE_FLOAT, STBR_COLORSPACE_LINEAR):
for (int n = 0; n < channels; n++)
((float*)output_buffer)[output_texel_index + n] = stbr__saturate(encode_buffer[encode_texel_index + n]);
break;
case STBR__DECODE(STBR_TYPE_FLOAT, STBR_COLORSPACE_SRGB):
for (int n = 0; n < channels; n++)
((float*)output_buffer)[output_texel_index + n] = stbr__linear_to_srgb(stbr__saturate(encode_buffer[encode_texel_index + n]));
break;
default:
STBR_UNIMPLEMENTED("Unknown type/colorspace/channels combination.");
break;
}
}
static void stbr__resample_vertical_upsample(stbr__info* stbr_info, int n, int in_first_scanline, int in_last_scanline, float in_center_of_out)
{
int x, k;
int output_w = stbr_info->output_w;
stbr__contributors* vertical_contributors = &stbr_info->vertical_contributors;
float* vertical_coefficients = stbr_info->vertical_coefficients;
int channels = stbr_info->channels;
int type = stbr_info->type;
int colorspace = stbr_info->colorspace;
int kernel_texel_width = stbr__get_filter_texel_width(stbr_info->filter, stbr_info->input_h, stbr_info->output_h);
void* output_data = stbr_info->output_data;
float* encode_buffer = stbr_info->encode_buffer;
int decode = STBR__DECODE(type, colorspace);
float* ring_buffer = stbr_info->ring_buffer;
int ring_buffer_begin_index = stbr_info->ring_buffer_begin_index;
int ring_buffer_first_scanline = stbr_info->ring_buffer_first_scanline;
int ring_buffer_last_scanline = stbr_info->ring_buffer_last_scanline;
int ring_buffer_length = stbr_info->ring_buffer_length_bytes/sizeof(float);
STBR_UNIMPLEMENTED(stbr_info->type != STBR_TYPE_UINT8);
stbr__calculate_coefficients_upsample(stbr_info, in_first_scanline, in_last_scanline, in_center_of_out, vertical_contributors, vertical_coefficients);
int n0 = vertical_contributors->n0;
int n1 = vertical_contributors->n1;
int output_row_index = n * stbr_info->output_stride_bytes;
STBR_DEBUG_ASSERT(stbr__use_height_upsampling(stbr_info));
STBR_DEBUG_ASSERT(n0 >= in_first_scanline);
STBR_DEBUG_ASSERT(n1 <= in_last_scanline);
for (x = 0; x < output_w; x++)
{
int in_texel_index = x * channels;
int out_texel_index = output_row_index + x * channels;
int coefficient_counter = 0;
STBR_DEBUG_ASSERT(n1 >= n0);
memset(encode_buffer, 0, sizeof(float) * channels);
for (k = n0; k <= n1; k++)
{
int coefficient_index = coefficient_counter++;
float* ring_buffer_entry = stbr__get_ring_buffer_scanline(k, ring_buffer, ring_buffer_begin_index, ring_buffer_first_scanline, kernel_texel_width, ring_buffer_length);
float coefficient = vertical_coefficients[coefficient_index];
int c;
for (c = 0; c < channels; c++)
encode_buffer[c] += ring_buffer_entry[in_texel_index + c] * coefficient;
}
stbr__encode_scanline(output_data, out_texel_index, encode_buffer, 0, channels, decode);
}
}
static void stbr__resample_vertical_downsample(stbr__info* stbr_info, int n, int in_first_scanline, int in_last_scanline, float in_center_of_out)
{
int x, k;
int output_w = stbr_info->output_w;
int output_h = stbr_info->output_h;
stbr__contributors* vertical_contributors = &stbr_info->vertical_contributors;
float* vertical_coefficients = stbr_info->vertical_coefficients;
int channels = stbr_info->channels;
int kernel_texel_width = stbr__get_filter_texel_width(stbr_info->filter, stbr_info->input_h, stbr_info->output_h);
void* output_data = stbr_info->output_data;
float* horizontal_buffer = stbr_info->horizontal_buffer;
float* ring_buffer = stbr_info->ring_buffer;
int ring_buffer_begin_index = stbr_info->ring_buffer_begin_index;
int ring_buffer_first_scanline = stbr_info->ring_buffer_first_scanline;
int ring_buffer_last_scanline = stbr_info->ring_buffer_last_scanline;
int ring_buffer_length = stbr_info->ring_buffer_length_bytes/sizeof(float);
stbr__calculate_coefficients_downsample(stbr_info, (float)stbr_info->output_h / stbr_info->input_h, in_first_scanline, in_last_scanline, in_center_of_out, vertical_contributors, vertical_coefficients);
int n0 = vertical_contributors->n0;
int n1 = vertical_contributors->n1;
int max_n = stbr__min(n1, output_h - 1);
STBR_DEBUG_ASSERT(!stbr__use_height_upsampling(stbr_info));
STBR_DEBUG_ASSERT(n0 >= in_first_scanline);
STBR_DEBUG_ASSERT(n1 <= in_last_scanline);
STBR_DEBUG_ASSERT(n1 >= n0);
// Using min and max to avoid writing into ring buffers that will be thrown out.
for (k = stbr__max(n0, 0); k <= max_n; k++)
{
int coefficient_index = k - n0;
float* ring_buffer_entry = stbr__get_ring_buffer_scanline(k, ring_buffer, ring_buffer_begin_index, ring_buffer_first_scanline, kernel_texel_width, ring_buffer_length);
float coefficient = vertical_coefficients[coefficient_index];
for (x = 0; x < output_w; x++)
{
int in_texel_index = x * channels;
int c;
for (c = 0; c < channels; c++)
ring_buffer_entry[in_texel_index + c] += horizontal_buffer[in_texel_index + c] * coefficient;
}
}
}
static void stbr__buffer_loop_upsample(stbr__info* stbr_info)
{
int y;
float scale_ratio = (float)stbr_info->output_h / stbr_info->input_h;
float out_scanlines_radius = stbr__filter_info_table[stbr_info->filter].support * scale_ratio;
STBR_DEBUG_ASSERT(stbr__use_height_upsampling(stbr_info));
for (y = 0; y < stbr_info->output_h; y++)
{
float in_center_of_out = 0; // Center of the current out scanline in the in scanline space
int in_first_scanline = 0, in_last_scanline = 0;
stbr__calculate_sample_range_upsample(y, out_scanlines_radius, scale_ratio, &in_first_scanline, &in_last_scanline, &in_center_of_out);
STBR_DEBUG_ASSERT(in_last_scanline - in_first_scanline <= stbr__get_filter_texel_width(stbr_info->filter, stbr_info->input_h, stbr_info->output_h));
STBR_DEBUG_ASSERT(in_first_scanline >= -stbr__get_filter_texel_margin(stbr_info->filter, stbr_info->input_h, stbr_info->output_h));
STBR_DEBUG_ASSERT(in_last_scanline < stbr_info->input_w + stbr__get_filter_texel_margin(stbr_info->filter, stbr_info->input_h, stbr_info->output_h));
if (stbr_info->ring_buffer_begin_index >= 0)
{
// Get rid of whatever we don't need anymore.
while (in_first_scanline > stbr_info->ring_buffer_first_scanline)
{
if (stbr_info->ring_buffer_first_scanline == stbr_info->ring_buffer_last_scanline)
{
// We just popped the last scanline off the ring buffer.
// Reset it to the empty state.
stbr_info->ring_buffer_begin_index = -1;
stbr_info->ring_buffer_first_scanline = 0;
stbr_info->ring_buffer_last_scanline = 0;
break;
}
else
{
stbr_info->ring_buffer_first_scanline++;
stbr_info->ring_buffer_begin_index = (stbr_info->ring_buffer_begin_index + 1) % stbr__get_filter_texel_width(stbr_info->filter, stbr_info->input_h, stbr_info->output_h);
}
}
}
// Load in new ones.
if (stbr_info->ring_buffer_begin_index < 0)
stbr__decode_and_resample_upsample(stbr_info, in_first_scanline);
while (in_last_scanline > stbr_info->ring_buffer_last_scanline)
stbr__decode_and_resample_upsample(stbr_info, stbr_info->ring_buffer_last_scanline + 1);
// Now all buffers should be ready to write a row of vertical sampling.
stbr__resample_vertical_upsample(stbr_info, y, in_first_scanline, in_last_scanline, in_center_of_out);
}
}
static void stbr__empty_ring_buffer(stbr__info* stbr_info, int first_necessary_scanline)
{
int output_stride_bytes = stbr_info->output_stride_bytes;
int channels = stbr_info->channels;
int type = stbr_info->type;
int colorspace = stbr_info->colorspace;
int output_w = stbr_info->output_w;
void* output_data = stbr_info->output_data;
int decode = STBR__DECODE(type, colorspace);
float* ring_buffer = stbr_info->ring_buffer;
int ring_buffer_length = stbr_info->ring_buffer_length_bytes/sizeof(float);
if (stbr_info->ring_buffer_begin_index >= 0)
{
// Get rid of whatever we don't need anymore.
while (first_necessary_scanline > stbr_info->ring_buffer_first_scanline)
{
STBR_UNIMPLEMENTED(stbr_info->type != STBR_TYPE_UINT8);
if (stbr_info->ring_buffer_first_scanline >= 0 && stbr_info->ring_buffer_first_scanline < stbr_info->output_h)
{
int x;
int output_row = stbr_info->ring_buffer_first_scanline * output_stride_bytes;
float* ring_buffer_entry = stbr__get_ring_buffer_entry(ring_buffer, stbr_info->ring_buffer_begin_index, ring_buffer_length);
for (x = 0; x < output_w; x++)
{
int texel_index = x * channels;
int ring_texel_index = texel_index;
int output_texel_index = output_row + texel_index;
stbr__encode_scanline(output_data, output_texel_index, ring_buffer_entry, ring_texel_index, channels, decode);
}
}
if (stbr_info->ring_buffer_first_scanline == stbr_info->ring_buffer_last_scanline)
{
// We just popped the last scanline off the ring buffer.
// Reset it to the empty state.
stbr_info->ring_buffer_begin_index = -1;
stbr_info->ring_buffer_first_scanline = 0;
stbr_info->ring_buffer_last_scanline = 0;
break;
}
else
{
stbr_info->ring_buffer_first_scanline++;
stbr_info->ring_buffer_begin_index = (stbr_info->ring_buffer_begin_index + 1) % stbr__get_filter_texel_width(stbr_info->filter, stbr_info->input_h, stbr_info->output_h);
}
}
}
}
static void stbr__buffer_loop_downsample(stbr__info* stbr_info)
{
int y;
float scale_ratio = (float)stbr_info->output_h / stbr_info->input_h;
float in_pixels_radius = stbr__filter_info_table[stbr_info->filter].support / scale_ratio;
int max_y = stbr_info->input_h + stbr__get_filter_texel_margin(stbr_info->filter, stbr_info->input_h, stbr_info->output_h);
STBR_DEBUG_ASSERT(!stbr__use_height_upsampling(stbr_info));
for (y = -stbr__get_filter_texel_margin(stbr_info->filter, stbr_info->input_h, stbr_info->output_h); y < max_y; y++)
{
float out_center_of_in; // Center of the current out scanline in the in scanline space
int out_first_scanline, out_last_scanline;
stbr__calculate_sample_range_downsample(y, in_pixels_radius, scale_ratio, &out_first_scanline, &out_last_scanline, &out_center_of_in);
STBR_DEBUG_ASSERT(out_last_scanline - out_first_scanline <= stbr__get_filter_texel_width(stbr_info->filter, stbr_info->input_h, stbr_info->output_h));
STBR_DEBUG_ASSERT(out_first_scanline >= -2 * stbr__get_filter_texel_margin(stbr_info->filter, stbr_info->input_h, stbr_info->output_h));
STBR_DEBUG_ASSERT(out_last_scanline < stbr_info->input_w + 2 * stbr__get_filter_texel_margin(stbr_info->filter, stbr_info->input_h, stbr_info->output_h));
stbr__empty_ring_buffer(stbr_info, out_first_scanline);
stbr__decode_and_resample_downsample(stbr_info, y);
// Load in new ones.
if (stbr_info->ring_buffer_begin_index < 0)
stbr__add_empty_ring_buffer_entry(stbr_info, out_first_scanline);
while (out_last_scanline > stbr_info->ring_buffer_last_scanline)
stbr__add_empty_ring_buffer_entry(stbr_info, stbr_info->ring_buffer_last_scanline + 1);
// Now the horizontal buffer is ready to write to all ring buffer rows.
stbr__resample_vertical_downsample(stbr_info, y, out_first_scanline, out_last_scanline, out_center_of_in);
}
stbr__empty_ring_buffer(stbr_info, stbr_info->output_h);
}
STBRDEF int stbr_resize_arbitrary(const void* input_data, int input_w, int input_h, int input_stride_in_bytes,
void* output_data, int output_w, int output_h, int output_stride_in_bytes,
int channels, stbr_type type, stbr_filter filter, stbr_edge edge, stbr_colorspace colorspace,
void* tempmem, stbr_size_t tempmem_size_in_bytes)
{
int width_stride_input = input_stride_in_bytes ? input_stride_in_bytes : channels * input_w;
int width_stride_output = output_stride_in_bytes ? output_stride_in_bytes : channels * output_w;
#ifdef STBR_DEBUG_OVERWRITE_TEST
#define OVERWRITE_ARRAY_SIZE 8
unsigned char overwrite_output_before_pre[OVERWRITE_ARRAY_SIZE];
unsigned char overwrite_tempmem_before_pre[OVERWRITE_ARRAY_SIZE];
unsigned char overwrite_output_after_pre[OVERWRITE_ARRAY_SIZE];
unsigned char overwrite_tempmem_after_pre[OVERWRITE_ARRAY_SIZE];
stbr_size_t begin_forbidden = width_stride_output * (output_h - 1) + output_w * channels;
memcpy(overwrite_output_before_pre, &((unsigned char*)output_data)[-OVERWRITE_ARRAY_SIZE], OVERWRITE_ARRAY_SIZE);
memcpy(overwrite_output_after_pre, &((unsigned char*)output_data)[begin_forbidden], OVERWRITE_ARRAY_SIZE);
memcpy(overwrite_tempmem_before_pre, &((unsigned char*)tempmem)[-OVERWRITE_ARRAY_SIZE], OVERWRITE_ARRAY_SIZE);
memcpy(overwrite_tempmem_after_pre, &((unsigned char*)tempmem)[tempmem_size_in_bytes], OVERWRITE_ARRAY_SIZE);
#endif
STBR_UNIMPLEMENTED(type != STBR_TYPE_UINT8);
STBR_ASSERT(filter != 0);
STBR_ASSERT(filter < STBR_ARRAY_SIZE(stbr__filter_info_table));
if (!tempmem)
return 0;
if (tempmem_size_in_bytes < stbr_calculate_memory(input_w, input_h, output_w, output_h, channels, filter))
return 0;
memset(tempmem, 0, tempmem_size_in_bytes);
stbr__info* stbr_info = (stbr__info*)tempmem;
stbr_info->input_data = input_data;
stbr_info->input_w = input_w;
stbr_info->input_h = input_h;
stbr_info->input_stride_bytes = width_stride_input;
stbr_info->output_data = output_data;
stbr_info->output_w = output_w;
stbr_info->output_h = output_h;
stbr_info->output_stride_bytes = width_stride_output;
stbr_info->channels = channels;
stbr_info->type = type;
stbr_info->filter = filter;
stbr_info->edge = edge;
stbr_info->colorspace = colorspace;
stbr_info->ring_buffer_length_bytes = output_w * channels * sizeof(float);
stbr_info->decode_buffer_texels = input_w + stbr__get_filter_texel_margin(filter, input_w, output_w) * 2;
#define STBR__NEXT_MEMPTR(current, old, newtype) (newtype*)(((unsigned char*)current) + old)
stbr_info->horizontal_contributors = STBR__NEXT_MEMPTR(stbr_info, sizeof(stbr__info), stbr__contributors);
stbr_info->horizontal_coefficients = STBR__NEXT_MEMPTR(stbr_info->horizontal_contributors, stbr__get_horizontal_contributors(filter, input_w, output_w) * sizeof(stbr__contributors), float);
stbr_info->vertical_coefficients = STBR__NEXT_MEMPTR(stbr_info->horizontal_coefficients, stbr__get_total_coefficients(filter, input_w, output_w) * sizeof(float), float);
stbr_info->decode_buffer = STBR__NEXT_MEMPTR(stbr_info->vertical_coefficients, stbr__get_filter_texel_width(filter, input_h, output_h) * sizeof(float), float);
if (stbr__use_height_upsampling(stbr_info))
{
stbr_info->horizontal_buffer = NULL;
stbr_info->ring_buffer = STBR__NEXT_MEMPTR(stbr_info->decode_buffer, stbr_info->decode_buffer_texels * channels * sizeof(float), float);
stbr_info->encode_buffer = STBR__NEXT_MEMPTR(stbr_info->ring_buffer, stbr_info->ring_buffer_length_bytes * stbr__get_filter_texel_width(filter, input_h, output_h), float);
STBR_DEBUG_ASSERT((size_t)STBR__NEXT_MEMPTR(stbr_info->encode_buffer, stbr_info->channels * sizeof(float), unsigned char) == (size_t)tempmem + tempmem_size_in_bytes);
}
else
{
stbr_info->horizontal_buffer = STBR__NEXT_MEMPTR(stbr_info->decode_buffer, stbr_info->decode_buffer_texels * channels * sizeof(float), float);
stbr_info->ring_buffer = STBR__NEXT_MEMPTR(stbr_info->horizontal_buffer, output_w * channels * sizeof(float), float);
stbr_info->encode_buffer = NULL;
STBR_DEBUG_ASSERT((size_t)STBR__NEXT_MEMPTR(stbr_info->ring_buffer, stbr_info->ring_buffer_length_bytes * stbr__get_filter_texel_width(filter, input_h, output_h), unsigned char) == (size_t)tempmem + tempmem_size_in_bytes);
}
#undef STBR__NEXT_MEMPTR
// This signals that the ring buffer is empty
stbr_info->ring_buffer_begin_index = -1;
stbr__calculate_horizontal_filters(stbr_info);
if (stbr__use_height_upsampling(stbr_info))
stbr__buffer_loop_upsample(stbr_info);
else
stbr__buffer_loop_downsample(stbr_info);
#ifdef STBR_DEBUG_OVERWRITE_TEST
STBR_DEBUG_ASSERT(memcmp(overwrite_output_before_pre, &((unsigned char*)output_data)[-OVERWRITE_ARRAY_SIZE], OVERWRITE_ARRAY_SIZE) == 0);
STBR_DEBUG_ASSERT(memcmp(overwrite_output_after_pre, &((unsigned char*)output_data)[begin_forbidden], OVERWRITE_ARRAY_SIZE) == 0);
STBR_DEBUG_ASSERT(memcmp(overwrite_tempmem_before_pre, &((unsigned char*)tempmem)[-OVERWRITE_ARRAY_SIZE], OVERWRITE_ARRAY_SIZE) == 0);
STBR_DEBUG_ASSERT(memcmp(overwrite_tempmem_after_pre, &((unsigned char*)tempmem)[tempmem_size_in_bytes], OVERWRITE_ARRAY_SIZE) == 0);
#endif
return 1;
}
STBRDEF stbr_size_t stbr_calculate_memory(int input_w, int input_h, int output_w, int output_h, int channels, stbr_filter filter)
{
STBR_ASSERT(filter != 0);
STBR_ASSERT(filter < STBR_ARRAY_SIZE(stbr__filter_info_table));
int texel_margin = stbr__get_filter_texel_margin(filter, input_w, output_w);
int info_size = sizeof(stbr__info);
int contributors_size = stbr__get_horizontal_contributors(filter, input_w, output_w) * sizeof(stbr__contributors);
int horizontal_coefficients_size = stbr__get_total_coefficients(filter, input_w, output_w) * sizeof(float);
int vertical_coefficients_size = stbr__get_filter_texel_width(filter, input_h, output_h) * sizeof(float);
int decode_buffer_size = (input_w + texel_margin*2) * channels * sizeof(float);
int horizontal_buffer_size = output_w * channels * sizeof(float);
int ring_buffer_size = output_w * channels * sizeof(float) * stbr__get_filter_texel_width(filter, input_h, output_h);
int encode_buffer_size = channels * sizeof(float);
if (stbr__use_height_upsampling_noinfo(output_h, input_h))
// The horizontal buffer is for when we're downsampling the height and we
// can't output the result of sampling the decode buffer directly into the
// ring buffers.
horizontal_buffer_size = 0;
else
// The encode buffer is to retain precision in the height upsampling method
// and isn't used when height downsampling.
encode_buffer_size = 0;
return info_size + contributors_size + horizontal_coefficients_size + vertical_coefficients_size + decode_buffer_size + horizontal_buffer_size + ring_buffer_size + encode_buffer_size;
}
#ifndef STBR_NO_MALLOC
STBRDEF int stbr_resize_srgb_uint8(const stbr_uint8* input_data, int input_w, int input_h,
stbr_uint8* output_data, int output_w, int output_h,
int channels, stbr_filter filter, stbr_edge edge)
{
size_t memory_required = stbr_calculate_memory(input_w, input_h, output_w, output_h, channels, filter);
void* extra_memory = malloc(memory_required);
if (!extra_memory)
return 0;
int result = stbr_resize_arbitrary(input_data, input_w, input_h, 0, output_data, output_w, output_h, 0, channels, STBR_TYPE_UINT8, filter, edge, STBR_COLORSPACE_SRGB, extra_memory, memory_required);
free(extra_memory);
return result;
}
STBRDEF int stbr_resize_srgb_uint16(const stbr_uint16* input_data, int input_w, int input_h,
stbr_uint16* output_data, int output_w, int output_h,
int channels, stbr_filter filter, stbr_edge edge)
{
size_t memory_required = stbr_calculate_memory(input_w, input_h, output_w, output_h, channels, filter);
void* extra_memory = malloc(memory_required);
if (!extra_memory)
return 0;
int result = stbr_resize_arbitrary(input_data, input_w, input_h, 0, output_data, output_w, output_h, 0, channels, STBR_TYPE_UINT16, filter, edge, STBR_COLORSPACE_SRGB, extra_memory, memory_required);
free(extra_memory);
return result;
}
STBRDEF int stbr_resize_srgb_uint32(const stbr_uint32* input_data, int input_w, int input_h,
stbr_uint32* output_data, int output_w, int output_h,
int channels, stbr_filter filter, stbr_edge edge)
{
size_t memory_required = stbr_calculate_memory(input_w, input_h, output_w, output_h, channels, filter);
void* extra_memory = malloc(memory_required);
if (!extra_memory)
return 0;
int result = stbr_resize_arbitrary(input_data, input_w, input_h, 0, output_data, output_w, output_h, 0, channels, STBR_TYPE_UINT32, filter, edge, STBR_COLORSPACE_SRGB, extra_memory, memory_required);
free(extra_memory);
return result;
}
STBRDEF int stbr_resize_srgb_float(const float* input_data, int input_w, int input_h,
float* output_data, int output_w, int output_h,
int channels, stbr_filter filter, stbr_edge edge)
{
size_t memory_required = stbr_calculate_memory(input_w, input_h, output_w, output_h, channels, filter);
void* extra_memory = malloc(memory_required);
if (!extra_memory)
return 0;
int result = stbr_resize_arbitrary(input_data, input_w, input_h, 0, output_data, output_w, output_h, 0, channels, STBR_TYPE_FLOAT, filter, edge, STBR_COLORSPACE_SRGB, extra_memory, memory_required);
free(extra_memory);
return result;
}
#endif // STBR_NO_MALLOC
#endif // STB_RESAMPLE_IMPLEMENTATION
/*
revision history:
0.50 (2014-07-29)
first released version
*/