mirror of https://github.com/nothings/stb.git
finalize scalar YCbCr conversion back-ported from SSE version;
add missing STBIDEFs to a few functions; update documentation with full 1.49 info even though most isn't implemented yetpull/59/head
Sean Barrett
parent
f259bf27e9
commit
bd6b78f268
152
stb_image.h
152
stb_image.h
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@ -7,6 +7,8 @@
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before you include this file in *one* C or C++ file to create the implementation.
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#define STBI_ASSERT(x) to avoid using assert.h.
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#define STBI_MALLOC, STBI_REALLOC, and STBI_FREE to avoid using malloc,realloc,free
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QUICK NOTES:
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Primarily of interest to game developers and other people who can
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@ -27,7 +29,56 @@
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- decode from arbitrary I/O callbacks
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- SIMD acceleration on x86/x64
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Latest revisions:
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Full documentation under "DOCUMENTATION" below.
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Revision 1.49 release notes:
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- The old STBI_SIMD system which allowed installing a user-defined
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IDCT etc. has been removed. If you need this, don't upgrade. My
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assumption is that almost nobody was doing this, and those who
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were will find the next bullet item more satisfactory anyway.
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- x86 platforms now make use of SSE2 SIMD instructions if available.
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This release is 2x faster on our test JPEGs, mostly due to SIMD.
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This work was done by Fabian "ryg" Giesen.
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- Compilation of SIMD code can be suppressed with
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#define STBI_NO_SIMD
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It should not be necessary to disable it unless you have issues
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compiling (e.g. using an x86 compiler which doesn't support SSE
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intrinsics or that doesn't support the method used to detect
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SSE2 support at run-time), and even those can be reported as
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bugs so I can refine the built-in compile-time checking to be
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smarter.
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- RGB values computed for JPEG images are slightly different from
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previous versions of stb_image. (This is due to using less
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integer precision in SIMD.) The C code has been adjusted so
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that the same RGB values will be computed regardless of whether
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SIMD support is available, so your app should always produce
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consistent results. But these results are slightly different from
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previous versions. (Specifically, about 3% of available YCbCr values
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will compute different RGB results from pre-1.49 versions by +-1;
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most of the deviating values are one smaller in the G channel.)
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- If you must produce consistent results with previous versions of
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stb_image, #define STBI_JPEG_OLD and you will get the same results
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you used to; however, you will not get the SIMD speedups for
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the YCbCr-to-RGB conversion step (although you should still see
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significant JPEG speedup from the other changes).
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Please note that STBI_JPEG_OLD is a temporary feature; it will be
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removed in future versions of the library. It is only intended for
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back-compatibility use.
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Latest revision history:
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1.49 (2014-12-25) optimize JPG, incl. x86 SIMD
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PGM/PPM support
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allocation macros
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stbi_load_into() -- load into pre-defined memory
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STBI_MALLOC,STBI_REALLOC,STBI_FREE
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1.48 (2014-12-14) fix incorrectly-named assert()
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1.47 (2014-12-14) 1/2/4-bit PNG support (both grayscale and paletted)
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optimize PNG
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@ -41,9 +92,6 @@
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See end of file for full revision history.
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TODO:
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stbi_info support for BMP,PSD,HDR,PIC
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============================ Contributors =========================
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@ -79,6 +127,8 @@
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#ifndef STBI_INCLUDE_STB_IMAGE_H
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#define STBI_INCLUDE_STB_IMAGE_H
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// DOCUMENTATION
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//
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// Limitations:
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// - no jpeg progressive support
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// - no 16-bit-per-channel PNG
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@ -248,14 +298,6 @@ extern "C" {
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// load image by filename, open file, or memory buffer
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//
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STBIDEF stbi_uc *stbi_load_from_memory(stbi_uc const *buffer, int len, int *x, int *y, int *comp, int req_comp);
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#ifndef STBI_NO_STDIO
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STBIDEF stbi_uc *stbi_load (char const *filename, int *x, int *y, int *comp, int req_comp);
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STBIDEF stbi_uc *stbi_load_from_file (FILE *f, int *x, int *y, int *comp, int req_comp);
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// for stbi_load_from_file, file pointer is left pointing immediately after image
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#endif
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typedef struct
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{
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int (*read) (void *user,char *data,int size); // fill 'data' with 'size' bytes. return number of bytes actually read
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@ -263,18 +305,26 @@ typedef struct
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int (*eof) (void *user); // returns nonzero if we are at end of file/data
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} stbi_io_callbacks;
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STBIDEF stbi_uc *stbi_load_from_callbacks (stbi_io_callbacks const *clbk, void *user, int *x, int *y, int *comp, int req_comp);
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STBIDEF stbi_uc *stbi_load (char const *filename, int *x, int *y, int *comp, int req_comp);
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STBIDEF stbi_uc *stbi_load_from_memory (stbi_uc const *buffer, int len , int *x, int *y, int *comp, int req_comp);
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STBIDEF stbi_uc *stbi_load_from_callbacks(stbi_io_callbacks const *clbk , void *user, int *x, int *y, int *comp, int req_comp);
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#ifndef STBI_NO_STDIO
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STBIDEF stbi_uc *stbi_load_from_file (FILE *f, int *x, int *y, int *comp, int req_comp);
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// for stbi_load_from_file, file pointer is left pointing immediately after image
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#endif
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#ifndef STBI_NO_HDR
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STBIDEF float *stbi_loadf_from_memory(stbi_uc const *buffer, int len, int *x, int *y, int *comp, int req_comp);
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#ifndef STBI_NO_STDIO
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STBIDEF float *stbi_loadf (char const *filename, int *x, int *y, int *comp, int req_comp);
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STBIDEF float *stbi_loadf_from_file (FILE *f, int *x, int *y, int *comp, int req_comp);
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#endif
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STBIDEF float *stbi_loadf (char const *filename, int *x, int *y, int *comp, int req_comp);
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STBIDEF float *stbi_loadf_from_memory (stbi_uc const *buffer, int len, int *x, int *y, int *comp, int req_comp);
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STBIDEF float *stbi_loadf_from_callbacks (stbi_io_callbacks const *clbk, void *user, int *x, int *y, int *comp, int req_comp);
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#ifndef STBI_NO_STDIO
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STBIDEF float *stbi_loadf_from_file (FILE *f, int *x, int *y, int *comp, int req_comp);
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#endif
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#endif
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#ifndef STBI_NO_HDR
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STBIDEF void stbi_hdr_to_ldr_gamma(float gamma);
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STBIDEF void stbi_hdr_to_ldr_scale(float scale);
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@ -282,7 +332,7 @@ STBIDEF stbi_uc *stbi_load_from_callbacks (stbi_io_callbacks const *clbk, void
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STBIDEF void stbi_ldr_to_hdr_scale(float scale);
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#endif // STBI_NO_HDR
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// stbi_is_hdr is always defined
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// stbi_is_hdr is always defined, but always returns false if STBI_NO_HDR
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STBIDEF int stbi_is_hdr_from_callbacks(stbi_io_callbacks const *clbk, void *user);
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STBIDEF int stbi_is_hdr_from_memory(stbi_uc const *buffer, int len);
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#ifndef STBI_NO_STDIO
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@ -648,7 +698,7 @@ static FILE *stbi__fopen(char const *filename, char const *mode)
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}
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STBIDEF unsigned char *stbi_load(char const *filename, int *x, int *y, int *comp, int req_comp)
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STBIDEF stbi_uc *stbi_load(char const *filename, int *x, int *y, int *comp, int req_comp)
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{
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FILE *f = stbi__fopen(filename, "rb");
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unsigned char *result;
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@ -658,7 +708,7 @@ STBIDEF unsigned char *stbi_load(char const *filename, int *x, int *y, int *comp
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return result;
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}
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STBIDEF unsigned char *stbi_load_from_file(FILE *f, int *x, int *y, int *comp, int req_comp)
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STBIDEF stbi_uc *stbi_load_from_file(FILE *f, int *x, int *y, int *comp, int req_comp)
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{
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unsigned char *result;
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stbi__context s;
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@ -672,14 +722,14 @@ STBIDEF unsigned char *stbi_load_from_file(FILE *f, int *x, int *y, int *comp, i
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}
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#endif //!STBI_NO_STDIO
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STBIDEF unsigned char *stbi_load_from_memory(stbi_uc const *buffer, int len, int *x, int *y, int *comp, int req_comp)
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STBIDEF stbi_uc *stbi_load_from_memory(stbi_uc const *buffer, int len, int *x, int *y, int *comp, int req_comp)
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{
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stbi__context s;
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stbi__start_mem(&s,buffer,len);
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return stbi_load_main(&s,x,y,comp,req_comp);
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}
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STBIDEF unsigned char *stbi_load_from_callbacks(stbi_io_callbacks const *clbk, void *user, int *x, int *y, int *comp, int req_comp)
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STBIDEF stbi_uc *stbi_load_from_callbacks(stbi_io_callbacks const *clbk, void *user, int *x, int *y, int *comp, int req_comp)
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{
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stbi__context s;
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stbi__start_callbacks(&s, (stbi_io_callbacks *) clbk, user);
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@ -740,7 +790,7 @@ STBIDEF float *stbi_loadf_from_file(FILE *f, int *x, int *y, int *comp, int req_
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// defined, for API simplicity; if STBI_NO_HDR is defined, it always
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// reports false!
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int stbi_is_hdr_from_memory(stbi_uc const *buffer, int len)
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STBIDEF int stbi_is_hdr_from_memory(stbi_uc const *buffer, int len)
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{
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#ifndef STBI_NO_HDR
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stbi__context s;
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@ -792,11 +842,11 @@ STBIDEF int stbi_is_hdr_from_callbacks(stbi_io_callbacks const *clbk, void
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static float stbi__h2l_gamma_i=1.0f/2.2f, stbi__h2l_scale_i=1.0f;
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static float stbi__l2h_gamma=2.2f, stbi__l2h_scale=1.0f;
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void stbi_hdr_to_ldr_gamma(float gamma) { stbi__h2l_gamma_i = 1/gamma; }
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void stbi_hdr_to_ldr_scale(float scale) { stbi__h2l_scale_i = 1/scale; }
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STBIDEF void stbi_hdr_to_ldr_gamma(float gamma) { stbi__h2l_gamma_i = 1/gamma; }
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STBIDEF void stbi_hdr_to_ldr_scale(float scale) { stbi__h2l_scale_i = 1/scale; }
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void stbi_ldr_to_hdr_gamma(float gamma) { stbi__l2h_gamma = gamma; }
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void stbi_ldr_to_hdr_scale(float scale) { stbi__l2h_scale = scale; }
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STBIDEF void stbi_ldr_to_hdr_gamma(float gamma) { stbi__l2h_gamma = gamma; }
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STBIDEF void stbi_ldr_to_hdr_scale(float scale) { stbi__l2h_scale = scale; }
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#endif
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@ -2112,10 +2162,10 @@ static stbi_uc *stbi__resample_row_generic(stbi_uc *out, stbi_uc *in_near, stbi_
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return out;
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}
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#ifdef STBI_JPEG_OLD
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// this is the same YCbCr-to-RGB calculation that stb_image has used
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// historically before the algorithm changes in 1.49
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#define float2fixed(x) ((int) ((x) * 65536 + 0.5))
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// 0.38 seconds on 3*anemones.jpg (0.25 with processor = Pro)
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// VC6 without processor=Pro is generating multiple LEAs per multiply!
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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)
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{
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int i;
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@ -2140,10 +2190,11 @@ static void stbi__YCbCr_to_RGB_row(stbi_uc *out, const stbi_uc *y, const stbi_uc
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out += step;
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}
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}
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#define float2fixed2(x) (((int) ((x) * 4096.0f + 0.5f)) << 8)
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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)
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#else
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// this is a reduced-precision calculation of YCbCr-to-RGB introduced
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// to make sure the code produces the same results in both SIMD and scalar
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#define float2fixed(x) (((int) ((x) * 4096.0f + 0.5f)) << 8)
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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)
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{
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int i;
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for (i=0; i < count; ++i) {
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@ -2151,11 +2202,9 @@ static void stbi__YCbCr_to_RGB_backport(stbi_uc *out, const stbi_uc *y, const st
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int r,g,b;
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int cr = pcr[i] - 128;
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int cb = pcb[i] - 128;
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r = y_fixed + cr*float2fixed2(1.40200f);
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g = y_fixed;
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g += (cr*-float2fixed2(0.71414f)) & 0xffff0000;
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g += (cb*-float2fixed2(0.34414f)) & 0xffff0000;
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b = y_fixed + cb*float2fixed2(1.77200f);
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r = y_fixed + cr* float2fixed(1.40200f);
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g = y_fixed + (cr*-float2fixed(0.71414f)) + ((cb*-float2fixed(0.34414f)) & 0xffff0000);
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b = y_fixed + cb* float2fixed(1.77200f);
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r >>= 20;
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g >>= 20;
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b >>= 20;
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@ -2169,6 +2218,7 @@ static void stbi__YCbCr_to_RGB_backport(stbi_uc *out, const stbi_uc *y, const st
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out += step;
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}
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}
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#endif
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#ifdef STBI_SSE2
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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)
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@ -2182,7 +2232,7 @@ static void stbi__YCbCr_to_RGB_sse2(stbi_uc *out, stbi_uc const *y, stbi_uc cons
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// note: unlike the IDCT, this isn't bit-identical to the integer version.
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if (step == 4) {
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// this is a fairly straightforward implementation and not super-optimized.
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__m128i signflip = _mm_set1_epi8(-0x80);
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__m128i signflip = _mm_set1_epi8(-0x80);
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__m128i cr_const0 = _mm_set1_epi16( (short) ( 1.40200f*4096.0f+0.5f));
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__m128i cr_const1 = _mm_set1_epi16( - (short) ( 0.71414f*4096.0f+0.5f));
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__m128i cb_const0 = _mm_set1_epi16( - (short) ( 0.34414f*4096.0f+0.5f));
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@ -2237,16 +2287,16 @@ static void stbi__YCbCr_to_RGB_sse2(stbi_uc *out, stbi_uc const *y, stbi_uc cons
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}
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for (; i < count; ++i) {
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int y_fixed = (y[i] << 16) + 32768; // rounding
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int y_fixed = (y[i] << 20) + (1<<19); // rounding
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int r,g,b;
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int cr = pcr[i] - 128;
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int cb = pcb[i] - 128;
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r = y_fixed + cr*float2fixed(1.40200f);
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g = y_fixed - cr*float2fixed(0.71414f) - cb*float2fixed(0.34414f);
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b = y_fixed + cb*float2fixed(1.77200f);
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r >>= 16;
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g >>= 16;
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b >>= 16;
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r = y_fixed + cr* float2fixed(1.40200f);
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g = y_fixed + cr*-float2fixed(0.71414f) + ((cb*-float2fixed(0.34414f)) & 0xffff0000);
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b = y_fixed + cb* float2fixed(1.77200f);
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r >>= 20;
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g >>= 20;
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b >>= 20;
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if ((unsigned) r > 255) { if (r < 0) r = 0; else r = 255; }
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if ((unsigned) g > 255) { if (g < 0) g = 0; else g = 255; }
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if ((unsigned) b > 255) { if (b < 0) b = 0; else b = 255; }
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@ -2269,7 +2319,9 @@ static void stbi__setup_jpeg(stbi__jpeg *j)
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#ifdef STBI_SSE2
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if (stbi__sse2_available()) {
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j->idct_block_kernel = stbi__idct_sse2;
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#ifndef STBI_JPEG_OLD
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j->YCbCr_to_RGB_kernel = stbi__YCbCr_to_RGB_sse2;
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#endif
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j->resample_row_hv_2_kernel = stbi__resample_row_hv_2_sse2;
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}
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#endif
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@ -9,7 +9,7 @@
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#define PNGSUITE_PRIMARY
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#if 1
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#if 0
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void test_ycbcr(void)
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{
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STBI_SIMD_ALIGN(unsigned char, y[256]);
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@ -28,15 +28,15 @@ void test_ycbcr(void)
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cb[k] = j;
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cr[k] = i;
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}
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stbi__YCbCr_to_RGB_sse2(out1[0], y, cb, cr, 256, 4);
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stbi__YCbCr_to_RGB_backport(out2[0], y, cb, cr, 256, 4);
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stbi__YCbCr_to_RGB_row(out1[0], y, cb, cr, 256, 4);
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stbi__YCbCr_to_RGB_sse2(out2[0], y, cb, cr, 256, 4);
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for (k=0; k < 256; ++k) {
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if (out1[k][0] != out2[k][0] || out1[k][1] != out2[k][1] || out1[k][2] != out2[k][2]) {
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int dist1 = abs(out1[k][0] - out2[k][0]);
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int dist2 = abs(out1[k][1] - out2[k][1]);
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int dist3 = abs(out1[k][2] - out2[k][2]);
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++count;
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if (dist2)
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if (out1[k][1] > out2[k][1])
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++bigcount;
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}
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}
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@ -50,7 +50,7 @@ void test_ycbcr(void)
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int main(int argc, char **argv)
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{
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int w,h;
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test_ycbcr();
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//test_ycbcr();
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if (argc > 1) {
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int i;
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for (i=1; i < argc; ++i) {
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Reference in New Issue