#if !defined(_FX_JPEG_TURBO_) | |
/* | |
* jccolor.c | |
* | |
* Copyright (C) 1991-1996, Thomas G. Lane. | |
* This file is part of the Independent JPEG Group's software. | |
* For conditions of distribution and use, see the accompanying README file. | |
* | |
* This file contains input colorspace conversion routines. | |
*/ | |
#define JPEG_INTERNALS | |
#include "jinclude.h" | |
#include "jpeglib.h" | |
/* Private subobject */ | |
typedef struct { | |
struct jpeg_color_converter pub; /* public fields */ | |
/* Private state for RGB->YCC conversion */ | |
INT32 * rgb_ycc_tab; /* => table for RGB to YCbCr conversion */ | |
} my_color_converter; | |
typedef my_color_converter * my_cconvert_ptr; | |
/**************** RGB -> YCbCr conversion: most common case **************/ | |
/* | |
* YCbCr is defined per CCIR 601-1, except that Cb and Cr are | |
* normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5. | |
* The conversion equations to be implemented are therefore | |
* Y = 0.29900 * R + 0.58700 * G + 0.11400 * B | |
* Cb = -0.16874 * R - 0.33126 * G + 0.50000 * B + CENTERJSAMPLE | |
* Cr = 0.50000 * R - 0.41869 * G - 0.08131 * B + CENTERJSAMPLE | |
* (These numbers are derived from TIFF 6.0 section 21, dated 3-June-92.) | |
* Note: older versions of the IJG code used a zero offset of MAXJSAMPLE/2, | |
* rather than CENTERJSAMPLE, for Cb and Cr. This gave equal positive and | |
* negative swings for Cb/Cr, but meant that grayscale values (Cb=Cr=0) | |
* were not represented exactly. Now we sacrifice exact representation of | |
* maximum red and maximum blue in order to get exact grayscales. | |
* | |
* To avoid floating-point arithmetic, we represent the fractional constants | |
* as integers scaled up by 2^16 (about 4 digits precision); we have to divide | |
* the products by 2^16, with appropriate rounding, to get the correct answer. | |
* | |
* For even more speed, we avoid doing any multiplications in the inner loop | |
* by precalculating the constants times R,G,B for all possible values. | |
* For 8-bit JSAMPLEs this is very reasonable (only 256 entries per table); | |
* for 12-bit samples it is still acceptable. It's not very reasonable for | |
* 16-bit samples, but if you want lossless storage you shouldn't be changing | |
* colorspace anyway. | |
* The CENTERJSAMPLE offsets and the rounding fudge-factor of 0.5 are included | |
* in the tables to save adding them separately in the inner loop. | |
*/ | |
#define SCALEBITS 16 /* speediest right-shift on some machines */ | |
#define CBCR_OFFSET ((INT32) CENTERJSAMPLE << SCALEBITS) | |
#define ONE_HALF ((INT32) 1 << (SCALEBITS-1)) | |
#define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5)) | |
/* We allocate one big table and divide it up into eight parts, instead of | |
* doing eight alloc_small requests. This lets us use a single table base | |
* address, which can be held in a register in the inner loops on many | |
* machines (more than can hold all eight addresses, anyway). | |
*/ | |
#define R_Y_OFF 0 /* offset to R => Y section */ | |
#define G_Y_OFF (1*(MAXJSAMPLE+1)) /* offset to G => Y section */ | |
#define B_Y_OFF (2*(MAXJSAMPLE+1)) /* etc. */ | |
#define R_CB_OFF (3*(MAXJSAMPLE+1)) | |
#define G_CB_OFF (4*(MAXJSAMPLE+1)) | |
#define B_CB_OFF (5*(MAXJSAMPLE+1)) | |
#define R_CR_OFF B_CB_OFF /* B=>Cb, R=>Cr are the same */ | |
#define G_CR_OFF (6*(MAXJSAMPLE+1)) | |
#define B_CR_OFF (7*(MAXJSAMPLE+1)) | |
#define TABLE_SIZE (8*(MAXJSAMPLE+1)) | |
/* | |
* Initialize for RGB->YCC colorspace conversion. | |
*/ | |
METHODDEF(void) | |
rgb_ycc_start (j_compress_ptr cinfo) | |
{ | |
my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert; | |
INT32 * rgb_ycc_tab; | |
INT32 i; | |
/* Allocate and fill in the conversion tables. */ | |
cconvert->rgb_ycc_tab = rgb_ycc_tab = (INT32 *) | |
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
(TABLE_SIZE * SIZEOF(INT32))); | |
for (i = 0; i <= MAXJSAMPLE; i++) { | |
rgb_ycc_tab[i+R_Y_OFF] = FIX(0.29900) * i; | |
rgb_ycc_tab[i+G_Y_OFF] = FIX(0.58700) * i; | |
rgb_ycc_tab[i+B_Y_OFF] = FIX(0.11400) * i + ONE_HALF; | |
rgb_ycc_tab[i+R_CB_OFF] = (-FIX(0.16874)) * i; | |
rgb_ycc_tab[i+G_CB_OFF] = (-FIX(0.33126)) * i; | |
/* We use a rounding fudge-factor of 0.5-epsilon for Cb and Cr. | |
* This ensures that the maximum output will round to MAXJSAMPLE | |
* not MAXJSAMPLE+1, and thus that we don't have to range-limit. | |
*/ | |
rgb_ycc_tab[i+B_CB_OFF] = FIX(0.50000) * i + CBCR_OFFSET + ONE_HALF-1; | |
/* B=>Cb and R=>Cr tables are the same | |
rgb_ycc_tab[i+R_CR_OFF] = FIX(0.50000) * i + CBCR_OFFSET + ONE_HALF-1; | |
*/ | |
rgb_ycc_tab[i+G_CR_OFF] = (-FIX(0.41869)) * i; | |
rgb_ycc_tab[i+B_CR_OFF] = (-FIX(0.08131)) * i; | |
} | |
} | |
/* | |
* Convert some rows of samples to the JPEG colorspace. | |
* | |
* Note that we change from the application's interleaved-pixel format | |
* to our internal noninterleaved, one-plane-per-component format. | |
* The input buffer is therefore three times as wide as the output buffer. | |
* | |
* A starting row offset is provided only for the output buffer. The caller | |
* can easily adjust the passed input_buf value to accommodate any row | |
* offset required on that side. | |
*/ | |
METHODDEF(void) | |
rgb_ycc_convert (j_compress_ptr cinfo, | |
JSAMPARRAY input_buf, JSAMPIMAGE output_buf, | |
JDIMENSION output_row, int num_rows) | |
{ | |
my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert; | |
register int r, g, b; | |
register INT32 * ctab = cconvert->rgb_ycc_tab; | |
register JSAMPROW inptr; | |
register JSAMPROW outptr0, outptr1, outptr2; | |
register JDIMENSION col; | |
JDIMENSION num_cols = cinfo->image_width; | |
while (--num_rows >= 0) { | |
inptr = *input_buf++; | |
outptr0 = output_buf[0][output_row]; | |
outptr1 = output_buf[1][output_row]; | |
outptr2 = output_buf[2][output_row]; | |
output_row++; | |
for (col = 0; col < num_cols; col++) { | |
r = GETJSAMPLE(inptr[RGB_RED]); | |
g = GETJSAMPLE(inptr[RGB_GREEN]); | |
b = GETJSAMPLE(inptr[RGB_BLUE]); | |
inptr += RGB_PIXELSIZE; | |
/* If the inputs are 0..MAXJSAMPLE, the outputs of these equations | |
* must be too; we do not need an explicit range-limiting operation. | |
* Hence the value being shifted is never negative, and we don't | |
* need the general RIGHT_SHIFT macro. | |
*/ | |
/* Y */ | |
outptr0[col] = (JSAMPLE) | |
((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF]) | |
>> SCALEBITS); | |
/* Cb */ | |
outptr1[col] = (JSAMPLE) | |
((ctab[r+R_CB_OFF] + ctab[g+G_CB_OFF] + ctab[b+B_CB_OFF]) | |
>> SCALEBITS); | |
/* Cr */ | |
outptr2[col] = (JSAMPLE) | |
((ctab[r+R_CR_OFF] + ctab[g+G_CR_OFF] + ctab[b+B_CR_OFF]) | |
>> SCALEBITS); | |
} | |
} | |
} | |
/**************** Cases other than RGB -> YCbCr **************/ | |
/* | |
* Convert some rows of samples to the JPEG colorspace. | |
* This version handles RGB->grayscale conversion, which is the same | |
* as the RGB->Y portion of RGB->YCbCr. | |
* We assume rgb_ycc_start has been called (we only use the Y tables). | |
*/ | |
METHODDEF(void) | |
rgb_gray_convert (j_compress_ptr cinfo, | |
JSAMPARRAY input_buf, JSAMPIMAGE output_buf, | |
JDIMENSION output_row, int num_rows) | |
{ | |
my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert; | |
register int r, g, b; | |
register INT32 * ctab = cconvert->rgb_ycc_tab; | |
register JSAMPROW inptr; | |
register JSAMPROW outptr; | |
register JDIMENSION col; | |
JDIMENSION num_cols = cinfo->image_width; | |
while (--num_rows >= 0) { | |
inptr = *input_buf++; | |
outptr = output_buf[0][output_row]; | |
output_row++; | |
for (col = 0; col < num_cols; col++) { | |
r = GETJSAMPLE(inptr[RGB_RED]); | |
g = GETJSAMPLE(inptr[RGB_GREEN]); | |
b = GETJSAMPLE(inptr[RGB_BLUE]); | |
inptr += RGB_PIXELSIZE; | |
/* Y */ | |
outptr[col] = (JSAMPLE) | |
((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF]) | |
>> SCALEBITS); | |
} | |
} | |
} | |
/* | |
* Convert some rows of samples to the JPEG colorspace. | |
* This version handles Adobe-style CMYK->YCCK conversion, | |
* where we convert R=1-C, G=1-M, and B=1-Y to YCbCr using the same | |
* conversion as above, while passing K (black) unchanged. | |
* We assume rgb_ycc_start has been called. | |
*/ | |
METHODDEF(void) | |
cmyk_ycck_convert (j_compress_ptr cinfo, | |
JSAMPARRAY input_buf, JSAMPIMAGE output_buf, | |
JDIMENSION output_row, int num_rows) | |
{ | |
my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert; | |
register int r, g, b; | |
register INT32 * ctab = cconvert->rgb_ycc_tab; | |
register JSAMPROW inptr; | |
register JSAMPROW outptr0, outptr1, outptr2, outptr3; | |
register JDIMENSION col; | |
JDIMENSION num_cols = cinfo->image_width; | |
while (--num_rows >= 0) { | |
inptr = *input_buf++; | |
outptr0 = output_buf[0][output_row]; | |
outptr1 = output_buf[1][output_row]; | |
outptr2 = output_buf[2][output_row]; | |
outptr3 = output_buf[3][output_row]; | |
output_row++; | |
for (col = 0; col < num_cols; col++) { | |
r = MAXJSAMPLE - GETJSAMPLE(inptr[0]); | |
g = MAXJSAMPLE - GETJSAMPLE(inptr[1]); | |
b = MAXJSAMPLE - GETJSAMPLE(inptr[2]); | |
/* K passes through as-is */ | |
outptr3[col] = inptr[3]; /* don't need GETJSAMPLE here */ | |
inptr += 4; | |
/* If the inputs are 0..MAXJSAMPLE, the outputs of these equations | |
* must be too; we do not need an explicit range-limiting operation. | |
* Hence the value being shifted is never negative, and we don't | |
* need the general RIGHT_SHIFT macro. | |
*/ | |
/* Y */ | |
outptr0[col] = (JSAMPLE) | |
((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF]) | |
>> SCALEBITS); | |
/* Cb */ | |
outptr1[col] = (JSAMPLE) | |
((ctab[r+R_CB_OFF] + ctab[g+G_CB_OFF] + ctab[b+B_CB_OFF]) | |
>> SCALEBITS); | |
/* Cr */ | |
outptr2[col] = (JSAMPLE) | |
((ctab[r+R_CR_OFF] + ctab[g+G_CR_OFF] + ctab[b+B_CR_OFF]) | |
>> SCALEBITS); | |
} | |
} | |
} | |
/* | |
* Convert some rows of samples to the JPEG colorspace. | |
* This version handles grayscale output with no conversion. | |
* The source can be either plain grayscale or YCbCr (since Y == gray). | |
*/ | |
METHODDEF(void) | |
grayscale_convert (j_compress_ptr cinfo, | |
JSAMPARRAY input_buf, JSAMPIMAGE output_buf, | |
JDIMENSION output_row, int num_rows) | |
{ | |
register JSAMPROW inptr; | |
register JSAMPROW outptr; | |
register JDIMENSION col; | |
JDIMENSION num_cols = cinfo->image_width; | |
int instride = cinfo->input_components; | |
while (--num_rows >= 0) { | |
inptr = *input_buf++; | |
outptr = output_buf[0][output_row]; | |
output_row++; | |
for (col = 0; col < num_cols; col++) { | |
outptr[col] = inptr[0]; /* don't need GETJSAMPLE() here */ | |
inptr += instride; | |
} | |
} | |
} | |
/* | |
* Convert some rows of samples to the JPEG colorspace. | |
* This version handles multi-component colorspaces without conversion. | |
* We assume input_components == num_components. | |
*/ | |
METHODDEF(void) | |
null_convert (j_compress_ptr cinfo, | |
JSAMPARRAY input_buf, JSAMPIMAGE output_buf, | |
JDIMENSION output_row, int num_rows) | |
{ | |
register JSAMPROW inptr; | |
register JSAMPROW outptr; | |
register JDIMENSION col; | |
register int ci; | |
int nc = cinfo->num_components; | |
JDIMENSION num_cols = cinfo->image_width; | |
while (--num_rows >= 0) { | |
/* It seems fastest to make a separate pass for each component. */ | |
for (ci = 0; ci < nc; ci++) { | |
inptr = *input_buf; | |
outptr = output_buf[ci][output_row]; | |
for (col = 0; col < num_cols; col++) { | |
outptr[col] = inptr[ci]; /* don't need GETJSAMPLE() here */ | |
inptr += nc; | |
} | |
} | |
input_buf++; | |
output_row++; | |
} | |
} | |
/* | |
* Empty method for start_pass. | |
*/ | |
METHODDEF(void) | |
null_method (j_compress_ptr cinfo) | |
{ | |
/* no work needed */ | |
} | |
/* | |
* Module initialization routine for input colorspace conversion. | |
*/ | |
GLOBAL(void) | |
jinit_color_converter (j_compress_ptr cinfo) | |
{ | |
my_cconvert_ptr cconvert; | |
cconvert = (my_cconvert_ptr) | |
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
SIZEOF(my_color_converter)); | |
cinfo->cconvert = (struct jpeg_color_converter *) cconvert; | |
/* set start_pass to null method until we find out differently */ | |
cconvert->pub.start_pass = null_method; | |
/* Make sure input_components agrees with in_color_space */ | |
switch (cinfo->in_color_space) { | |
case JCS_GRAYSCALE: | |
if (cinfo->input_components != 1) | |
ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE); | |
break; | |
case JCS_RGB: | |
#if RGB_PIXELSIZE != 3 | |
if (cinfo->input_components != RGB_PIXELSIZE) | |
ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE); | |
break; | |
#endif /* else share code with YCbCr */ | |
case JCS_YCbCr: | |
if (cinfo->input_components != 3) | |
ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE); | |
break; | |
case JCS_CMYK: | |
case JCS_YCCK: | |
if (cinfo->input_components != 4) | |
ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE); | |
break; | |
default: /* JCS_UNKNOWN can be anything */ | |
if (cinfo->input_components < 1) | |
ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE); | |
break; | |
} | |
/* Check num_components, set conversion method based on requested space */ | |
switch (cinfo->jpeg_color_space) { | |
case JCS_GRAYSCALE: | |
if (cinfo->num_components != 1) | |
ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); | |
if (cinfo->in_color_space == JCS_GRAYSCALE) | |
cconvert->pub.color_convert = grayscale_convert; | |
else if (cinfo->in_color_space == JCS_RGB) { | |
cconvert->pub.start_pass = rgb_ycc_start; | |
cconvert->pub.color_convert = rgb_gray_convert; | |
} else if (cinfo->in_color_space == JCS_YCbCr) | |
cconvert->pub.color_convert = grayscale_convert; | |
else | |
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); | |
break; | |
case JCS_RGB: | |
if (cinfo->num_components != 3) | |
ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); | |
if (cinfo->in_color_space == JCS_RGB && RGB_PIXELSIZE == 3) | |
cconvert->pub.color_convert = null_convert; | |
else | |
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); | |
break; | |
case JCS_YCbCr: | |
if (cinfo->num_components != 3) | |
ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); | |
if (cinfo->in_color_space == JCS_RGB) { | |
cconvert->pub.start_pass = rgb_ycc_start; | |
cconvert->pub.color_convert = rgb_ycc_convert; | |
} else if (cinfo->in_color_space == JCS_YCbCr) | |
cconvert->pub.color_convert = null_convert; | |
else | |
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); | |
break; | |
case JCS_CMYK: | |
if (cinfo->num_components != 4) | |
ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); | |
if (cinfo->in_color_space == JCS_CMYK) | |
cconvert->pub.color_convert = null_convert; | |
else | |
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); | |
break; | |
case JCS_YCCK: | |
if (cinfo->num_components != 4) | |
ERREXIT(cinfo, JERR_BAD_J_COLORSPACE); | |
if (cinfo->in_color_space == JCS_CMYK) { | |
cconvert->pub.start_pass = rgb_ycc_start; | |
cconvert->pub.color_convert = cmyk_ycck_convert; | |
} else if (cinfo->in_color_space == JCS_YCCK) | |
cconvert->pub.color_convert = null_convert; | |
else | |
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); | |
break; | |
default: /* allow null conversion of JCS_UNKNOWN */ | |
if (cinfo->jpeg_color_space != cinfo->in_color_space || | |
cinfo->num_components != cinfo->input_components) | |
ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL); | |
cconvert->pub.color_convert = null_convert; | |
break; | |
} | |
} | |
#endif //_FX_JPEG_TURBO_ |