anulax
/
stb
1
0
Fork 0
Code Issues Pull Requests Packages project_board Releases Wiki Activity

finalize scalar YCbCr conversion back-ported from SSE version;

Browse Source 
add missing STBIDEFs to a few functions;
update documentation with full 1.49 info even though most isn't implemented yet
master
Sean Barrett ago%!(EXTRA string=11 years)
parent f259bf27e9
commit bd6b78f268
2 changed files with 104 additions and 52 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 146
      stb_image.h
  2. 10
      tests/image_test.c

146
stb_image.h
Unescape View File

@ -7,6 +7,8 @@
before you include this file in *one* C or C++ file to create the implementation.
#define STBI_ASSERT(x) to avoid using assert.h.
#define STBI_MALLOC, STBI_REALLOC, and STBI_FREE to avoid using malloc,realloc,free
QUICK NOTES:
Primarily of interest to game developers and other people who can
@ -27,7 +29,56 @@
- decode from arbitrary I/O callbacks
- SIMD acceleration on x86/x64
Latest revisions:
Full documentation under "DOCUMENTATION" below.
Revision 1.49 release notes:
- The old STBI_SIMD system which allowed installing a user-defined
IDCT etc. has been removed. If you need this, don't upgrade. My
assumption is that almost nobody was doing this, and those who
were will find the next bullet item more satisfactory anyway.
- x86 platforms now make use of SSE2 SIMD instructions if available.
This release is 2x faster on our test JPEGs, mostly due to SIMD.
This work was done by Fabian "ryg" Giesen.
- Compilation of SIMD code can be suppressed with
#define STBI_NO_SIMD
It should not be necessary to disable it unless you have issues
compiling (e.g. using an x86 compiler which doesn't support SSE
intrinsics or that doesn't support the method used to detect
SSE2 support at run-time), and even those can be reported as
bugs so I can refine the built-in compile-time checking to be
smarter.
- RGB values computed for JPEG images are slightly different from
previous versions of stb_image. (This is due to using less
integer precision in SIMD.) The C code has been adjusted so
that the same RGB values will be computed regardless of whether
SIMD support is available, so your app should always produce
consistent results. But these results are slightly different from
previous versions. (Specifically, about 3% of available YCbCr values
will compute different RGB results from pre-1.49 versions by +-1;
most of the deviating values are one smaller in the G channel.)
- If you must produce consistent results with previous versions of
stb_image, #define STBI_JPEG_OLD and you will get the same results
you used to; however, you will not get the SIMD speedups for
the YCbCr-to-RGB conversion step (although you should still see
significant JPEG speedup from the other changes).
Please note that STBI_JPEG_OLD is a temporary feature; it will be
removed in future versions of the library. It is only intended for
back-compatibility use.
Latest revision history:
1.49 (2014-12-25) optimize JPG, incl. x86 SIMD
PGM/PPM support
allocation macros
stbi_load_into() -- load into pre-defined memory
STBI_MALLOC,STBI_REALLOC,STBI_FREE
1.48 (2014-12-14) fix incorrectly-named assert()
1.47 (2014-12-14) 1/2/4-bit PNG support (both grayscale and paletted)
optimize PNG
@ -41,9 +92,6 @@
See end of file for full revision history.
TODO:
stbi_info support for BMP,PSD,HDR,PIC
============================ Contributors =========================
@ -79,6 +127,8 @@
#ifndef STBI_INCLUDE_STB_IMAGE_H
#define STBI_INCLUDE_STB_IMAGE_H
// DOCUMENTATION
//
// Limitations:
// - no jpeg progressive support
// - no 16-bit-per-channel PNG
@ -248,14 +298,6 @@ extern "C" {
// load image by filename, open file, or memory buffer
//
STBIDEF stbi_uc *stbi_load_from_memory(stbi_uc const *buffer, int len, int *x, int *y, int *comp, int req_comp);
#ifndef STBI_NO_STDIO
STBIDEF stbi_uc *stbi_load (char const *filename, int *x, int *y, int *comp, int req_comp);
STBIDEF stbi_uc *stbi_load_from_file (FILE *f, int *x, int *y, int *comp, int req_comp);
// for stbi_load_from_file, file pointer is left pointing immediately after image
#endif
typedef struct
{
int (*read) (void *user,char *data,int size); // fill 'data' with 'size' bytes. return number of bytes actually read
@ -263,18 +305,26 @@ typedef struct
int (*eof) (void *user); // returns nonzero if we are at end of file/data
} stbi_io_callbacks;
STBIDEF stbi_uc *stbi_load_from_callbacks (stbi_io_callbacks const *clbk, void *user, int *x, int *y, int *comp, int req_comp);
STBIDEF stbi_uc *stbi_load (char const *filename, int *x, int *y, int *comp, int req_comp);
STBIDEF stbi_uc *stbi_load_from_memory (stbi_uc const *buffer, int len , int *x, int *y, int *comp, int req_comp);
STBIDEF stbi_uc *stbi_load_from_callbacks(stbi_io_callbacks const *clbk , void *user, int *x, int *y, int *comp, int req_comp);
#ifndef STBI_NO_STDIO
STBIDEF stbi_uc *stbi_load_from_file (FILE *f, int *x, int *y, int *comp, int req_comp);
// for stbi_load_from_file, file pointer is left pointing immediately after image
#endif
#ifndef STBI_NO_HDR
STBIDEF float *stbi_loadf_from_memory(stbi_uc const *buffer, int len, int *x, int *y, int *comp, int req_comp);
STBIDEF float *stbi_loadf (char const *filename, int *x, int *y, int *comp, int req_comp);
STBIDEF float *stbi_loadf_from_memory (stbi_uc const *buffer, int len, int *x, int *y, int *comp, int req_comp);
STBIDEF float *stbi_loadf_from_callbacks (stbi_io_callbacks const *clbk, void *user, int *x, int *y, int *comp, int req_comp);
#ifndef STBI_NO_STDIO
STBIDEF float *stbi_loadf (char const *filename, int *x, int *y, int *comp, int req_comp);
STBIDEF float *stbi_loadf_from_file (FILE *f, int *x, int *y, int *comp, int req_comp);
#endif
STBIDEF float *stbi_loadf_from_callbacks (stbi_io_callbacks const *clbk, void *user, int *x, int *y, int *comp, int req_comp);
#endif
#ifndef STBI_NO_HDR
STBIDEF void stbi_hdr_to_ldr_gamma(float gamma);
STBIDEF void stbi_hdr_to_ldr_scale(float scale);
@ -282,7 +332,7 @@ STBIDEF stbi_uc *stbi_load_from_callbacks (stbi_io_callbacks const *clbk, void
STBIDEF void stbi_ldr_to_hdr_scale(float scale);
#endif // STBI_NO_HDR
// stbi_is_hdr is always defined
// stbi_is_hdr is always defined, but always returns false if STBI_NO_HDR
STBIDEF int stbi_is_hdr_from_callbacks(stbi_io_callbacks const *clbk, void *user);
STBIDEF int stbi_is_hdr_from_memory(stbi_uc const *buffer, int len);
#ifndef STBI_NO_STDIO
@ -648,7 +698,7 @@ static FILE *stbi__fopen(char const *filename, char const *mode)
}
STBIDEF unsigned char *stbi_load(char const *filename, int *x, int *y, int *comp, int req_comp)
STBIDEF stbi_uc *stbi_load(char const *filename, int *x, int *y, int *comp, int req_comp)
{
FILE *f = stbi__fopen(filename, "rb");
unsigned char *result;
@ -658,7 +708,7 @@ STBIDEF unsigned char *stbi_load(char const *filename, int *x, int *y, int *comp
return result;
}
STBIDEF unsigned char *stbi_load_from_file(FILE *f, int *x, int *y, int *comp, int req_comp)
STBIDEF stbi_uc *stbi_load_from_file(FILE *f, int *x, int *y, int *comp, int req_comp)
{
unsigned char *result;
stbi__context s;
@ -672,14 +722,14 @@ STBIDEF unsigned char *stbi_load_from_file(FILE *f, int *x, int *y, int *comp, i
}
#endif //!STBI_NO_STDIO
STBIDEF unsigned char *stbi_load_from_memory(stbi_uc const *buffer, int len, int *x, int *y, int *comp, int req_comp)
STBIDEF stbi_uc *stbi_load_from_memory(stbi_uc const *buffer, int len, int *x, int *y, int *comp, int req_comp)
{
stbi__context s;
stbi__start_mem(&s,buffer,len);
return stbi_load_main(&s,x,y,comp,req_comp);
}
STBIDEF unsigned char *stbi_load_from_callbacks(stbi_io_callbacks const *clbk, void *user, int *x, int *y, int *comp, int req_comp)
STBIDEF stbi_uc *stbi_load_from_callbacks(stbi_io_callbacks const *clbk, void *user, int *x, int *y, int *comp, int req_comp)
{
stbi__context s;
stbi__start_callbacks(&s, (stbi_io_callbacks *) clbk, user);
@ -740,7 +790,7 @@ STBIDEF float *stbi_loadf_from_file(FILE *f, int *x, int *y, int *comp, int req_
// defined, for API simplicity; if STBI_NO_HDR is defined, it always
// reports false!
int stbi_is_hdr_from_memory(stbi_uc const *buffer, int len)
STBIDEF int stbi_is_hdr_from_memory(stbi_uc const *buffer, int len)
{
#ifndef STBI_NO_HDR
stbi__context s;
@ -792,11 +842,11 @@ STBIDEF int stbi_is_hdr_from_callbacks(stbi_io_callbacks const *clbk, void
static float stbi__h2l_gamma_i=1.0f/2.2f, stbi__h2l_scale_i=1.0f;
static float stbi__l2h_gamma=2.2f, stbi__l2h_scale=1.0f;
void stbi_hdr_to_ldr_gamma(float gamma) { stbi__h2l_gamma_i = 1/gamma; }
void stbi_hdr_to_ldr_scale(float scale) { stbi__h2l_scale_i = 1/scale; }
STBIDEF void stbi_hdr_to_ldr_gamma(float gamma) { stbi__h2l_gamma_i = 1/gamma; }
STBIDEF void stbi_hdr_to_ldr_scale(float scale) { stbi__h2l_scale_i = 1/scale; }
void stbi_ldr_to_hdr_gamma(float gamma) { stbi__l2h_gamma = gamma; }
void stbi_ldr_to_hdr_scale(float scale) { stbi__l2h_scale = scale; }
STBIDEF void stbi_ldr_to_hdr_gamma(float gamma) { stbi__l2h_gamma = gamma; }
STBIDEF void stbi_ldr_to_hdr_scale(float scale) { stbi__l2h_scale = scale; }
#endif
@ -2112,10 +2162,10 @@ static stbi_uc *stbi__resample_row_generic(stbi_uc *out, stbi_uc *in_near, stbi_
return out;
}
#ifdef STBI_JPEG_OLD
// this is the same YCbCr-to-RGB calculation that stb_image has used
// historically before the algorithm changes in 1.49
#define float2fixed(x) ((int) ((x) * 65536 + 0.5))
// 0.38 seconds on 3*anemones.jpg (0.25 with processor = Pro)
// VC6 without processor=Pro is generating multiple LEAs per multiply!
static void stbi__YCbCr_to_RGB_row(stbi_uc *out, const stbi_uc *y, const stbi_uc *pcb, const stbi_uc *pcr, int count, int step)
{
int i;
@ -2140,10 +2190,11 @@ static void stbi__YCbCr_to_RGB_row(stbi_uc *out, const stbi_uc *y, const stbi_uc
out += step;
}
}
#define float2fixed2(x) (((int) ((x) * 4096.0f + 0.5f)) << 8)
static void stbi__YCbCr_to_RGB_backport(stbi_uc *out, const stbi_uc *y, const stbi_uc *pcb, const stbi_uc *pcr, int count, int step)
#else
// this is a reduced-precision calculation of YCbCr-to-RGB introduced
// to make sure the code produces the same results in both SIMD and scalar
#define float2fixed(x) (((int) ((x) * 4096.0f + 0.5f)) << 8)
static void stbi__YCbCr_to_RGB_row(stbi_uc *out, const stbi_uc *y, const stbi_uc *pcb, const stbi_uc *pcr, int count, int step)
{
int i;
for (i=0; i < count; ++i) {
@ -2151,11 +2202,9 @@ static void stbi__YCbCr_to_RGB_backport(stbi_uc *out, const stbi_uc *y, const st
int r,g,b;
int cr = pcr[i] - 128;
int cb = pcb[i] - 128;
r = y_fixed + cr*float2fixed2(1.40200f);
g = y_fixed;
g += (cr*-float2fixed2(0.71414f)) & 0xffff0000;
g += (cb*-float2fixed2(0.34414f)) & 0xffff0000;
b = y_fixed + cb*float2fixed2(1.77200f);
r = y_fixed + cr* float2fixed(1.40200f);
g = y_fixed + (cr*-float2fixed(0.71414f)) + ((cb*-float2fixed(0.34414f)) & 0xffff0000);
b = y_fixed + cb* float2fixed(1.77200f);
r >>= 20;
g >>= 20;
b >>= 20;
@ -2169,6 +2218,7 @@ static void stbi__YCbCr_to_RGB_backport(stbi_uc *out, const stbi_uc *y, const st
out += step;
}
}
#endif
#ifdef STBI_SSE2
static void stbi__YCbCr_to_RGB_sse2(stbi_uc *out, stbi_uc const *y, stbi_uc const *pcb, stbi_uc const *pcr, int count, int step)
@ -2182,7 +2232,7 @@ static void stbi__YCbCr_to_RGB_sse2(stbi_uc *out, stbi_uc const *y, stbi_uc cons
// note: unlike the IDCT, this isn't bit-identical to the integer version.
if (step == 4) {
// this is a fairly straightforward implementation and not super-optimized.
__m128i signflip = _mm_set1_epi8(-0x80);
__m128i signflip = _mm_set1_epi8(-0x80);
__m128i cr_const0 = _mm_set1_epi16( (short) ( 1.40200f*4096.0f+0.5f));
__m128i cr_const1 = _mm_set1_epi16( - (short) ( 0.71414f*4096.0f+0.5f));
__m128i cb_const0 = _mm_set1_epi16( - (short) ( 0.34414f*4096.0f+0.5f));
@ -2237,16 +2287,16 @@ static void stbi__YCbCr_to_RGB_sse2(stbi_uc *out, stbi_uc const *y, stbi_uc cons
}
for (; i < count; ++i) {
int y_fixed = (y[i] << 16) + 32768; // rounding
int y_fixed = (y[i] << 20) + (1<<19); // rounding
int r,g,b;
int cr = pcr[i] - 128;
int cb = pcb[i] - 128;
r = y_fixed + cr*float2fixed(1.40200f);
g = y_fixed - cr*float2fixed(0.71414f) - cb*float2fixed(0.34414f);
b = y_fixed + cb*float2fixed(1.77200f);
r >>= 16;
g >>= 16;
b >>= 16;
r = y_fixed + cr* float2fixed(1.40200f);
g = y_fixed + cr*-float2fixed(0.71414f) + ((cb*-float2fixed(0.34414f)) & 0xffff0000);
b = y_fixed + cb* float2fixed(1.77200f);
r >>= 20;
g >>= 20;
b >>= 20;
if ((unsigned) r > 255) { if (r < 0) r = 0; else r = 255; }
if ((unsigned) g > 255) { if (g < 0) g = 0; else g = 255; }
if ((unsigned) b > 255) { if (b < 0) b = 0; else b = 255; }
@ -2269,7 +2319,9 @@ static void stbi__setup_jpeg(stbi__jpeg *j)
#ifdef STBI_SSE2
if (stbi__sse2_available()) {
j->idct_block_kernel = stbi__idct_sse2;
#ifndef STBI_JPEG_OLD
j->YCbCr_to_RGB_kernel = stbi__YCbCr_to_RGB_sse2;
#endif
j->resample_row_hv_2_kernel = stbi__resample_row_hv_2_sse2;
}
#endif

10
tests/image_test.c
Unescape View File

@ -9,7 +9,7 @@
#define PNGSUITE_PRIMARY
#if 1
#if 0
void test_ycbcr(void)
{
STBI_SIMD_ALIGN(unsigned char, y[256]);
@ -28,15 +28,15 @@ void test_ycbcr(void)
cb[k] = j;
cr[k] = i;
}
stbi__YCbCr_to_RGB_sse2(out1[0], y, cb, cr, 256, 4);
stbi__YCbCr_to_RGB_backport(out2[0], y, cb, cr, 256, 4);
stbi__YCbCr_to_RGB_row(out1[0], y, cb, cr, 256, 4);
stbi__YCbCr_to_RGB_sse2(out2[0], y, cb, cr, 256, 4);
for (k=0; k < 256; ++k) {
if (out1[k][0] != out2[k][0] || out1[k][1] != out2[k][1] || out1[k][2] != out2[k][2]) {
int dist1 = abs(out1[k][0] - out2[k][0]);
int dist2 = abs(out1[k][1] - out2[k][1]);
int dist3 = abs(out1[k][2] - out2[k][2]);
++count;
if (dist2)
if (out1[k][1] > out2[k][1])
++bigcount;
}
}
@ -50,7 +50,7 @@ void test_ycbcr(void)
int main(int argc, char **argv)
{
int w,h;
test_ycbcr();
//test_ycbcr();
if (argc > 1) {
int i;
for (i=1; i < argc; ++i) {

Write Preview
Loading…
Cancel
Save