nuclear@2: /*
nuclear@2:  * jdcolor.c
nuclear@2:  *
nuclear@2:  * Copyright (C) 1991-1997, Thomas G. Lane.
nuclear@2:  * This file is part of the Independent JPEG Group's software.
nuclear@2:  * For conditions of distribution and use, see the accompanying README file.
nuclear@2:  *
nuclear@2:  * This file contains output colorspace conversion routines.
nuclear@2:  */
nuclear@2: 
nuclear@2: #define JPEG_INTERNALS
nuclear@2: #include "jinclude.h"
nuclear@2: #include "jpeglib.h"
nuclear@2: 
nuclear@2: 
nuclear@2: /* Private subobject */
nuclear@2: 
nuclear@2: typedef struct {
nuclear@2:   struct jpeg_color_deconverter pub; /* public fields */
nuclear@2: 
nuclear@2:   /* Private state for YCC->RGB conversion */
nuclear@2:   int * Cr_r_tab;		/* => table for Cr to R conversion */
nuclear@2:   int * Cb_b_tab;		/* => table for Cb to B conversion */
nuclear@2:   INT32 * Cr_g_tab;		/* => table for Cr to G conversion */
nuclear@2:   INT32 * Cb_g_tab;		/* => table for Cb to G conversion */
nuclear@2: } my_color_deconverter;
nuclear@2: 
nuclear@2: typedef my_color_deconverter * my_cconvert_ptr;
nuclear@2: 
nuclear@2: 
nuclear@2: /**************** YCbCr -> RGB conversion: most common case **************/
nuclear@2: 
nuclear@2: /*
nuclear@2:  * YCbCr is defined per CCIR 601-1, except that Cb and Cr are
nuclear@2:  * normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5.
nuclear@2:  * The conversion equations to be implemented are therefore
nuclear@2:  *	R = Y                + 1.40200 * Cr
nuclear@2:  *	G = Y - 0.34414 * Cb - 0.71414 * Cr
nuclear@2:  *	B = Y + 1.77200 * Cb
nuclear@2:  * where Cb and Cr represent the incoming values less CENTERJSAMPLE.
nuclear@2:  * (These numbers are derived from TIFF 6.0 section 21, dated 3-June-92.)
nuclear@2:  *
nuclear@2:  * To avoid floating-point arithmetic, we represent the fractional constants
nuclear@2:  * as integers scaled up by 2^16 (about 4 digits precision); we have to divide
nuclear@2:  * the products by 2^16, with appropriate rounding, to get the correct answer.
nuclear@2:  * Notice that Y, being an integral input, does not contribute any fraction
nuclear@2:  * so it need not participate in the rounding.
nuclear@2:  *
nuclear@2:  * For even more speed, we avoid doing any multiplications in the inner loop
nuclear@2:  * by precalculating the constants times Cb and Cr for all possible values.
nuclear@2:  * For 8-bit JSAMPLEs this is very reasonable (only 256 entries per table);
nuclear@2:  * for 12-bit samples it is still acceptable.  It's not very reasonable for
nuclear@2:  * 16-bit samples, but if you want lossless storage you shouldn't be changing
nuclear@2:  * colorspace anyway.
nuclear@2:  * The Cr=>R and Cb=>B values can be rounded to integers in advance; the
nuclear@2:  * values for the G calculation are left scaled up, since we must add them
nuclear@2:  * together before rounding.
nuclear@2:  */
nuclear@2: 
nuclear@2: #define SCALEBITS	16	/* speediest right-shift on some machines */
nuclear@2: #define ONE_HALF	((INT32) 1 << (SCALEBITS-1))
nuclear@2: #define FIX(x)		((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Initialize tables for YCC->RGB colorspace conversion.
nuclear@2:  */
nuclear@2: 
nuclear@2: LOCAL(void)
nuclear@2: build_ycc_rgb_table (j_decompress_ptr cinfo)
nuclear@2: {
nuclear@2:   my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
nuclear@2:   int i;
nuclear@2:   INT32 x;
nuclear@2:   SHIFT_TEMPS
nuclear@2: 
nuclear@2:   cconvert->Cr_r_tab = (int *)
nuclear@2:     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@2: 				(MAXJSAMPLE+1) * SIZEOF(int));
nuclear@2:   cconvert->Cb_b_tab = (int *)
nuclear@2:     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@2: 				(MAXJSAMPLE+1) * SIZEOF(int));
nuclear@2:   cconvert->Cr_g_tab = (INT32 *)
nuclear@2:     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@2: 				(MAXJSAMPLE+1) * SIZEOF(INT32));
nuclear@2:   cconvert->Cb_g_tab = (INT32 *)
nuclear@2:     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@2: 				(MAXJSAMPLE+1) * SIZEOF(INT32));
nuclear@2: 
nuclear@2:   for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
nuclear@2:     /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
nuclear@2:     /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
nuclear@2:     /* Cr=>R value is nearest int to 1.40200 * x */
nuclear@2:     cconvert->Cr_r_tab[i] = (int)
nuclear@2: 		    RIGHT_SHIFT(FIX(1.40200) * x + ONE_HALF, SCALEBITS);
nuclear@2:     /* Cb=>B value is nearest int to 1.77200 * x */
nuclear@2:     cconvert->Cb_b_tab[i] = (int)
nuclear@2: 		    RIGHT_SHIFT(FIX(1.77200) * x + ONE_HALF, SCALEBITS);
nuclear@2:     /* Cr=>G value is scaled-up -0.71414 * x */
nuclear@2:     cconvert->Cr_g_tab[i] = (- FIX(0.71414)) * x;
nuclear@2:     /* Cb=>G value is scaled-up -0.34414 * x */
nuclear@2:     /* We also add in ONE_HALF so that need not do it in inner loop */
nuclear@2:     cconvert->Cb_g_tab[i] = (- FIX(0.34414)) * x + ONE_HALF;
nuclear@2:   }
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Convert some rows of samples to the output colorspace.
nuclear@2:  *
nuclear@2:  * Note that we change from noninterleaved, one-plane-per-component format
nuclear@2:  * to interleaved-pixel format.  The output buffer is therefore three times
nuclear@2:  * as wide as the input buffer.
nuclear@2:  * A starting row offset is provided only for the input buffer.  The caller
nuclear@2:  * can easily adjust the passed output_buf value to accommodate any row
nuclear@2:  * offset required on that side.
nuclear@2:  */
nuclear@2: 
nuclear@2: METHODDEF(void)
nuclear@2: ycc_rgb_convert (j_decompress_ptr cinfo,
nuclear@2: 		 JSAMPIMAGE input_buf, JDIMENSION input_row,
nuclear@2: 		 JSAMPARRAY output_buf, int num_rows)
nuclear@2: {
nuclear@2:   my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
nuclear@2:   register int y, cb, cr;
nuclear@2:   register JSAMPROW outptr;
nuclear@2:   register JSAMPROW inptr0, inptr1, inptr2;
nuclear@2:   register JDIMENSION col;
nuclear@2:   JDIMENSION num_cols = cinfo->output_width;
nuclear@2:   /* copy these pointers into registers if possible */
nuclear@2:   register JSAMPLE * range_limit = cinfo->sample_range_limit;
nuclear@2:   register int * Crrtab = cconvert->Cr_r_tab;
nuclear@2:   register int * Cbbtab = cconvert->Cb_b_tab;
nuclear@2:   register INT32 * Crgtab = cconvert->Cr_g_tab;
nuclear@2:   register INT32 * Cbgtab = cconvert->Cb_g_tab;
nuclear@2:   SHIFT_TEMPS
nuclear@2: 
nuclear@2:   while (--num_rows >= 0) {
nuclear@2:     inptr0 = input_buf[0][input_row];
nuclear@2:     inptr1 = input_buf[1][input_row];
nuclear@2:     inptr2 = input_buf[2][input_row];
nuclear@2:     input_row++;
nuclear@2:     outptr = *output_buf++;
nuclear@2:     for (col = 0; col < num_cols; col++) {
nuclear@2:       y  = GETJSAMPLE(inptr0[col]);
nuclear@2:       cb = GETJSAMPLE(inptr1[col]);
nuclear@2:       cr = GETJSAMPLE(inptr2[col]);
nuclear@2:       /* Range-limiting is essential due to noise introduced by DCT losses. */
nuclear@2:       outptr[RGB_RED] =   range_limit[y + Crrtab[cr]];
nuclear@2:       outptr[RGB_GREEN] = range_limit[y +
nuclear@2: 			      ((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr],
nuclear@2: 						 SCALEBITS))];
nuclear@2:       outptr[RGB_BLUE] =  range_limit[y + Cbbtab[cb]];
nuclear@2:       outptr += RGB_PIXELSIZE;
nuclear@2:     }
nuclear@2:   }
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /**************** Cases other than YCbCr -> RGB **************/
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Color conversion for no colorspace change: just copy the data,
nuclear@2:  * converting from separate-planes to interleaved representation.
nuclear@2:  */
nuclear@2: 
nuclear@2: METHODDEF(void)
nuclear@2: null_convert (j_decompress_ptr cinfo,
nuclear@2: 	      JSAMPIMAGE input_buf, JDIMENSION input_row,
nuclear@2: 	      JSAMPARRAY output_buf, int num_rows)
nuclear@2: {
nuclear@2:   register JSAMPROW inptr, outptr;
nuclear@2:   register JDIMENSION count;
nuclear@2:   register int num_components = cinfo->num_components;
nuclear@2:   JDIMENSION num_cols = cinfo->output_width;
nuclear@2:   int ci;
nuclear@2: 
nuclear@2:   while (--num_rows >= 0) {
nuclear@2:     for (ci = 0; ci < num_components; ci++) {
nuclear@2:       inptr = input_buf[ci][input_row];
nuclear@2:       outptr = output_buf[0] + ci;
nuclear@2:       for (count = num_cols; count > 0; count--) {
nuclear@2: 	*outptr = *inptr++;	/* needn't bother with GETJSAMPLE() here */
nuclear@2: 	outptr += num_components;
nuclear@2:       }
nuclear@2:     }
nuclear@2:     input_row++;
nuclear@2:     output_buf++;
nuclear@2:   }
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Color conversion for grayscale: just copy the data.
nuclear@2:  * This also works for YCbCr -> grayscale conversion, in which
nuclear@2:  * we just copy the Y (luminance) component and ignore chrominance.
nuclear@2:  */
nuclear@2: 
nuclear@2: METHODDEF(void)
nuclear@2: grayscale_convert (j_decompress_ptr cinfo,
nuclear@2: 		   JSAMPIMAGE input_buf, JDIMENSION input_row,
nuclear@2: 		   JSAMPARRAY output_buf, int num_rows)
nuclear@2: {
nuclear@2:   jcopy_sample_rows(input_buf[0], (int) input_row, output_buf, 0,
nuclear@2: 		    num_rows, cinfo->output_width);
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Convert grayscale to RGB: just duplicate the graylevel three times.
nuclear@2:  * This is provided to support applications that don't want to cope
nuclear@2:  * with grayscale as a separate case.
nuclear@2:  */
nuclear@2: 
nuclear@2: METHODDEF(void)
nuclear@2: gray_rgb_convert (j_decompress_ptr cinfo,
nuclear@2: 		  JSAMPIMAGE input_buf, JDIMENSION input_row,
nuclear@2: 		  JSAMPARRAY output_buf, int num_rows)
nuclear@2: {
nuclear@2:   register JSAMPROW inptr, outptr;
nuclear@2:   register JDIMENSION col;
nuclear@2:   JDIMENSION num_cols = cinfo->output_width;
nuclear@2: 
nuclear@2:   while (--num_rows >= 0) {
nuclear@2:     inptr = input_buf[0][input_row++];
nuclear@2:     outptr = *output_buf++;
nuclear@2:     for (col = 0; col < num_cols; col++) {
nuclear@2:       /* We can dispense with GETJSAMPLE() here */
nuclear@2:       outptr[RGB_RED] = outptr[RGB_GREEN] = outptr[RGB_BLUE] = inptr[col];
nuclear@2:       outptr += RGB_PIXELSIZE;
nuclear@2:     }
nuclear@2:   }
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Adobe-style YCCK->CMYK conversion.
nuclear@2:  * We convert YCbCr to R=1-C, G=1-M, and B=1-Y using the same
nuclear@2:  * conversion as above, while passing K (black) unchanged.
nuclear@2:  * We assume build_ycc_rgb_table has been called.
nuclear@2:  */
nuclear@2: 
nuclear@2: METHODDEF(void)
nuclear@2: ycck_cmyk_convert (j_decompress_ptr cinfo,
nuclear@2: 		   JSAMPIMAGE input_buf, JDIMENSION input_row,
nuclear@2: 		   JSAMPARRAY output_buf, int num_rows)
nuclear@2: {
nuclear@2:   my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
nuclear@2:   register int y, cb, cr;
nuclear@2:   register JSAMPROW outptr;
nuclear@2:   register JSAMPROW inptr0, inptr1, inptr2, inptr3;
nuclear@2:   register JDIMENSION col;
nuclear@2:   JDIMENSION num_cols = cinfo->output_width;
nuclear@2:   /* copy these pointers into registers if possible */
nuclear@2:   register JSAMPLE * range_limit = cinfo->sample_range_limit;
nuclear@2:   register int * Crrtab = cconvert->Cr_r_tab;
nuclear@2:   register int * Cbbtab = cconvert->Cb_b_tab;
nuclear@2:   register INT32 * Crgtab = cconvert->Cr_g_tab;
nuclear@2:   register INT32 * Cbgtab = cconvert->Cb_g_tab;
nuclear@2:   SHIFT_TEMPS
nuclear@2: 
nuclear@2:   while (--num_rows >= 0) {
nuclear@2:     inptr0 = input_buf[0][input_row];
nuclear@2:     inptr1 = input_buf[1][input_row];
nuclear@2:     inptr2 = input_buf[2][input_row];
nuclear@2:     inptr3 = input_buf[3][input_row];
nuclear@2:     input_row++;
nuclear@2:     outptr = *output_buf++;
nuclear@2:     for (col = 0; col < num_cols; col++) {
nuclear@2:       y  = GETJSAMPLE(inptr0[col]);
nuclear@2:       cb = GETJSAMPLE(inptr1[col]);
nuclear@2:       cr = GETJSAMPLE(inptr2[col]);
nuclear@2:       /* Range-limiting is essential due to noise introduced by DCT losses. */
nuclear@2:       outptr[0] = range_limit[MAXJSAMPLE - (y + Crrtab[cr])];	/* red */
nuclear@2:       outptr[1] = range_limit[MAXJSAMPLE - (y +			/* green */
nuclear@2: 			      ((int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr],
nuclear@2: 						 SCALEBITS)))];
nuclear@2:       outptr[2] = range_limit[MAXJSAMPLE - (y + Cbbtab[cb])];	/* blue */
nuclear@2:       /* K passes through unchanged */
nuclear@2:       outptr[3] = inptr3[col];	/* don't need GETJSAMPLE here */
nuclear@2:       outptr += 4;
nuclear@2:     }
nuclear@2:   }
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Empty method for start_pass.
nuclear@2:  */
nuclear@2: 
nuclear@2: METHODDEF(void)
nuclear@2: start_pass_dcolor (j_decompress_ptr cinfo)
nuclear@2: {
nuclear@2:   /* no work needed */
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Module initialization routine for output colorspace conversion.
nuclear@2:  */
nuclear@2: 
nuclear@2: GLOBAL(void)
nuclear@2: jinit_color_deconverter (j_decompress_ptr cinfo)
nuclear@2: {
nuclear@2:   my_cconvert_ptr cconvert;
nuclear@2:   int ci;
nuclear@2: 
nuclear@2:   cconvert = (my_cconvert_ptr)
nuclear@2:     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@2: 				SIZEOF(my_color_deconverter));
nuclear@2:   cinfo->cconvert = (struct jpeg_color_deconverter *) cconvert;
nuclear@2:   cconvert->pub.start_pass = start_pass_dcolor;
nuclear@2: 
nuclear@2:   /* Make sure num_components agrees with jpeg_color_space */
nuclear@2:   switch (cinfo->jpeg_color_space) {
nuclear@2:   case JCS_GRAYSCALE:
nuclear@2:     if (cinfo->num_components != 1)
nuclear@2:       ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
nuclear@2:     break;
nuclear@2: 
nuclear@2:   case JCS_RGB:
nuclear@2:   case JCS_YCbCr:
nuclear@2:     if (cinfo->num_components != 3)
nuclear@2:       ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
nuclear@2:     break;
nuclear@2: 
nuclear@2:   case JCS_CMYK:
nuclear@2:   case JCS_YCCK:
nuclear@2:     if (cinfo->num_components != 4)
nuclear@2:       ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
nuclear@2:     break;
nuclear@2: 
nuclear@2:   default:			/* JCS_UNKNOWN can be anything */
nuclear@2:     if (cinfo->num_components < 1)
nuclear@2:       ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
nuclear@2:     break;
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* Set out_color_components and conversion method based on requested space.
nuclear@2:    * Also clear the component_needed flags for any unused components,
nuclear@2:    * so that earlier pipeline stages can avoid useless computation.
nuclear@2:    */
nuclear@2: 
nuclear@2:   switch (cinfo->out_color_space) {
nuclear@2:   case JCS_GRAYSCALE:
nuclear@2:     cinfo->out_color_components = 1;
nuclear@2:     if (cinfo->jpeg_color_space == JCS_GRAYSCALE ||
nuclear@2: 	cinfo->jpeg_color_space == JCS_YCbCr) {
nuclear@2:       cconvert->pub.color_convert = grayscale_convert;
nuclear@2:       /* For color->grayscale conversion, only the Y (0) component is needed */
nuclear@2:       for (ci = 1; ci < cinfo->num_components; ci++)
nuclear@2: 	cinfo->comp_info[ci].component_needed = FALSE;
nuclear@2:     } else
nuclear@2:       ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
nuclear@2:     break;
nuclear@2: 
nuclear@2:   case JCS_RGB:
nuclear@2:     cinfo->out_color_components = RGB_PIXELSIZE;
nuclear@2:     if (cinfo->jpeg_color_space == JCS_YCbCr) {
nuclear@2:       cconvert->pub.color_convert = ycc_rgb_convert;
nuclear@2:       build_ycc_rgb_table(cinfo);
nuclear@2:     } else if (cinfo->jpeg_color_space == JCS_GRAYSCALE) {
nuclear@2:       cconvert->pub.color_convert = gray_rgb_convert;
nuclear@2:     } else if (cinfo->jpeg_color_space == JCS_RGB && RGB_PIXELSIZE == 3) {
nuclear@2:       cconvert->pub.color_convert = null_convert;
nuclear@2:     } else
nuclear@2:       ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
nuclear@2:     break;
nuclear@2: 
nuclear@2:   case JCS_CMYK:
nuclear@2:     cinfo->out_color_components = 4;
nuclear@2:     if (cinfo->jpeg_color_space == JCS_YCCK) {
nuclear@2:       cconvert->pub.color_convert = ycck_cmyk_convert;
nuclear@2:       build_ycc_rgb_table(cinfo);
nuclear@2:     } else if (cinfo->jpeg_color_space == JCS_CMYK) {
nuclear@2:       cconvert->pub.color_convert = null_convert;
nuclear@2:     } else
nuclear@2:       ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
nuclear@2:     break;
nuclear@2: 
nuclear@2:   default:
nuclear@2:     /* Permit null conversion to same output space */
nuclear@2:     if (cinfo->out_color_space == cinfo->jpeg_color_space) {
nuclear@2:       cinfo->out_color_components = cinfo->num_components;
nuclear@2:       cconvert->pub.color_convert = null_convert;
nuclear@2:     } else			/* unsupported non-null conversion */
nuclear@2:       ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
nuclear@2:     break;
nuclear@2:   }
nuclear@2: 
nuclear@2:   if (cinfo->quantize_colors)
nuclear@2:     cinfo->output_components = 1; /* single colormapped output component */
nuclear@2:   else
nuclear@2:     cinfo->output_components = cinfo->out_color_components;
nuclear@2: }