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nuclear@1
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1 /*
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2 * jccolor.c
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3 *
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4 * Copyright (C) 1991-1996, Thomas G. Lane.
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5 * This file is part of the Independent JPEG Group's software.
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6 * For conditions of distribution and use, see the accompanying README file.
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7 *
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8 * This file contains input colorspace conversion routines.
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9 */
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10
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11 #define JPEG_INTERNALS
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12 #include "jinclude.h"
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13 #include "jpeglib.h"
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14
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15
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16 /* Private subobject */
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17
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18 typedef struct {
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19 struct jpeg_color_converter pub; /* public fields */
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20
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21 /* Private state for RGB->YCC conversion */
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22 INT32 * rgb_ycc_tab; /* => table for RGB to YCbCr conversion */
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23 } my_color_converter;
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24
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25 typedef my_color_converter * my_cconvert_ptr;
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26
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27
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28 /**************** RGB -> YCbCr conversion: most common case **************/
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29
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30 /*
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31 * YCbCr is defined per CCIR 601-1, except that Cb and Cr are
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32 * normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5.
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33 * The conversion equations to be implemented are therefore
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34 * Y = 0.29900 * R + 0.58700 * G + 0.11400 * B
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35 * Cb = -0.16874 * R - 0.33126 * G + 0.50000 * B + CENTERJSAMPLE
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36 * Cr = 0.50000 * R - 0.41869 * G - 0.08131 * B + CENTERJSAMPLE
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37 * (These numbers are derived from TIFF 6.0 section 21, dated 3-June-92.)
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38 * Note: older versions of the IJG code used a zero offset of MAXJSAMPLE/2,
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39 * rather than CENTERJSAMPLE, for Cb and Cr. This gave equal positive and
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40 * negative swings for Cb/Cr, but meant that grayscale values (Cb=Cr=0)
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41 * were not represented exactly. Now we sacrifice exact representation of
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42 * maximum red and maximum blue in order to get exact grayscales.
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43 *
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44 * To avoid floating-point arithmetic, we represent the fractional constants
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45 * as integers scaled up by 2^16 (about 4 digits precision); we have to divide
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46 * the products by 2^16, with appropriate rounding, to get the correct answer.
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47 *
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48 * For even more speed, we avoid doing any multiplications in the inner loop
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49 * by precalculating the constants times R,G,B for all possible values.
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50 * For 8-bit JSAMPLEs this is very reasonable (only 256 entries per table);
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51 * for 12-bit samples it is still acceptable. It's not very reasonable for
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52 * 16-bit samples, but if you want lossless storage you shouldn't be changing
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53 * colorspace anyway.
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54 * The CENTERJSAMPLE offsets and the rounding fudge-factor of 0.5 are included
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55 * in the tables to save adding them separately in the inner loop.
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56 */
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57
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58 #define SCALEBITS 16 /* speediest right-shift on some machines */
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59 #define CBCR_OFFSET ((INT32) CENTERJSAMPLE << SCALEBITS)
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60 #define ONE_HALF ((INT32) 1 << (SCALEBITS-1))
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61 #define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
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62
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63 /* We allocate one big table and divide it up into eight parts, instead of
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64 * doing eight alloc_small requests. This lets us use a single table base
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65 * address, which can be held in a register in the inner loops on many
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66 * machines (more than can hold all eight addresses, anyway).
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67 */
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68
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69 #define R_Y_OFF 0 /* offset to R => Y section */
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70 #define G_Y_OFF (1*(MAXJSAMPLE+1)) /* offset to G => Y section */
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71 #define B_Y_OFF (2*(MAXJSAMPLE+1)) /* etc. */
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72 #define R_CB_OFF (3*(MAXJSAMPLE+1))
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73 #define G_CB_OFF (4*(MAXJSAMPLE+1))
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74 #define B_CB_OFF (5*(MAXJSAMPLE+1))
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75 #define R_CR_OFF B_CB_OFF /* B=>Cb, R=>Cr are the same */
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76 #define G_CR_OFF (6*(MAXJSAMPLE+1))
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77 #define B_CR_OFF (7*(MAXJSAMPLE+1))
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78 #define TABLE_SIZE (8*(MAXJSAMPLE+1))
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79
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80
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81 /*
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82 * Initialize for RGB->YCC colorspace conversion.
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83 */
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84
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85 METHODDEF(void)
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86 rgb_ycc_start (j_compress_ptr cinfo)
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87 {
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88 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
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89 INT32 * rgb_ycc_tab;
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90 INT32 i;
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91
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92 /* Allocate and fill in the conversion tables. */
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93 cconvert->rgb_ycc_tab = rgb_ycc_tab = (INT32 *)
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94 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
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95 (TABLE_SIZE * SIZEOF(INT32)));
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96
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97 for (i = 0; i <= MAXJSAMPLE; i++) {
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98 rgb_ycc_tab[i+R_Y_OFF] = FIX(0.29900) * i;
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99 rgb_ycc_tab[i+G_Y_OFF] = FIX(0.58700) * i;
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100 rgb_ycc_tab[i+B_Y_OFF] = FIX(0.11400) * i + ONE_HALF;
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101 rgb_ycc_tab[i+R_CB_OFF] = (-FIX(0.16874)) * i;
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102 rgb_ycc_tab[i+G_CB_OFF] = (-FIX(0.33126)) * i;
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nuclear@1
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103 /* We use a rounding fudge-factor of 0.5-epsilon for Cb and Cr.
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104 * This ensures that the maximum output will round to MAXJSAMPLE
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105 * not MAXJSAMPLE+1, and thus that we don't have to range-limit.
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106 */
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107 rgb_ycc_tab[i+B_CB_OFF] = FIX(0.50000) * i + CBCR_OFFSET + ONE_HALF-1;
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108 /* B=>Cb and R=>Cr tables are the same
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109 rgb_ycc_tab[i+R_CR_OFF] = FIX(0.50000) * i + CBCR_OFFSET + ONE_HALF-1;
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110 */
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111 rgb_ycc_tab[i+G_CR_OFF] = (-FIX(0.41869)) * i;
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112 rgb_ycc_tab[i+B_CR_OFF] = (-FIX(0.08131)) * i;
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113 }
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114 }
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115
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116
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117 /*
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118 * Convert some rows of samples to the JPEG colorspace.
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119 *
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120 * Note that we change from the application's interleaved-pixel format
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121 * to our internal noninterleaved, one-plane-per-component format.
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122 * The input buffer is therefore three times as wide as the output buffer.
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123 *
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124 * A starting row offset is provided only for the output buffer. The caller
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125 * can easily adjust the passed input_buf value to accommodate any row
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126 * offset required on that side.
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127 */
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128
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129 METHODDEF(void)
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130 rgb_ycc_convert (j_compress_ptr cinfo,
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131 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
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132 JDIMENSION output_row, int num_rows)
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133 {
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134 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
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135 register int r, g, b;
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136 register INT32 * ctab = cconvert->rgb_ycc_tab;
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137 register JSAMPROW inptr;
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138 register JSAMPROW outptr0, outptr1, outptr2;
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139 register JDIMENSION col;
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140 JDIMENSION num_cols = cinfo->image_width;
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141
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142 while (--num_rows >= 0) {
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143 inptr = *input_buf++;
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144 outptr0 = output_buf[0][output_row];
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145 outptr1 = output_buf[1][output_row];
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146 outptr2 = output_buf[2][output_row];
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147 output_row++;
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148 for (col = 0; col < num_cols; col++) {
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149 r = GETJSAMPLE(inptr[RGB_RED]);
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150 g = GETJSAMPLE(inptr[RGB_GREEN]);
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151 b = GETJSAMPLE(inptr[RGB_BLUE]);
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152 inptr += RGB_PIXELSIZE;
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153 /* If the inputs are 0..MAXJSAMPLE, the outputs of these equations
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154 * must be too; we do not need an explicit range-limiting operation.
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155 * Hence the value being shifted is never negative, and we don't
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156 * need the general RIGHT_SHIFT macro.
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157 */
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158 /* Y */
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159 outptr0[col] = (JSAMPLE)
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160 ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
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161 >> SCALEBITS);
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162 /* Cb */
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163 outptr1[col] = (JSAMPLE)
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164 ((ctab[r+R_CB_OFF] + ctab[g+G_CB_OFF] + ctab[b+B_CB_OFF])
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165 >> SCALEBITS);
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166 /* Cr */
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167 outptr2[col] = (JSAMPLE)
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168 ((ctab[r+R_CR_OFF] + ctab[g+G_CR_OFF] + ctab[b+B_CR_OFF])
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169 >> SCALEBITS);
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170 }
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171 }
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172 }
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173
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174
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175 /**************** Cases other than RGB -> YCbCr **************/
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176
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177
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178 /*
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179 * Convert some rows of samples to the JPEG colorspace.
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180 * This version handles RGB->grayscale conversion, which is the same
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181 * as the RGB->Y portion of RGB->YCbCr.
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182 * We assume rgb_ycc_start has been called (we only use the Y tables).
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183 */
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184
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185 METHODDEF(void)
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186 rgb_gray_convert (j_compress_ptr cinfo,
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187 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
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188 JDIMENSION output_row, int num_rows)
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189 {
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190 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
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191 register int r, g, b;
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192 register INT32 * ctab = cconvert->rgb_ycc_tab;
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193 register JSAMPROW inptr;
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194 register JSAMPROW outptr;
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195 register JDIMENSION col;
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196 JDIMENSION num_cols = cinfo->image_width;
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197
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198 while (--num_rows >= 0) {
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199 inptr = *input_buf++;
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200 outptr = output_buf[0][output_row];
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201 output_row++;
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202 for (col = 0; col < num_cols; col++) {
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203 r = GETJSAMPLE(inptr[RGB_RED]);
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204 g = GETJSAMPLE(inptr[RGB_GREEN]);
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205 b = GETJSAMPLE(inptr[RGB_BLUE]);
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206 inptr += RGB_PIXELSIZE;
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207 /* Y */
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208 outptr[col] = (JSAMPLE)
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209 ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
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210 >> SCALEBITS);
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211 }
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212 }
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213 }
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214
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215
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216 /*
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217 * Convert some rows of samples to the JPEG colorspace.
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218 * This version handles Adobe-style CMYK->YCCK conversion,
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219 * where we convert R=1-C, G=1-M, and B=1-Y to YCbCr using the same
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220 * conversion as above, while passing K (black) unchanged.
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221 * We assume rgb_ycc_start has been called.
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222 */
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223
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224 METHODDEF(void)
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225 cmyk_ycck_convert (j_compress_ptr cinfo,
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226 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
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227 JDIMENSION output_row, int num_rows)
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228 {
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229 my_cconvert_ptr cconvert = (my_cconvert_ptr) cinfo->cconvert;
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230 register int r, g, b;
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231 register INT32 * ctab = cconvert->rgb_ycc_tab;
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232 register JSAMPROW inptr;
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233 register JSAMPROW outptr0, outptr1, outptr2, outptr3;
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234 register JDIMENSION col;
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235 JDIMENSION num_cols = cinfo->image_width;
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236
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237 while (--num_rows >= 0) {
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238 inptr = *input_buf++;
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239 outptr0 = output_buf[0][output_row];
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240 outptr1 = output_buf[1][output_row];
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241 outptr2 = output_buf[2][output_row];
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242 outptr3 = output_buf[3][output_row];
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243 output_row++;
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244 for (col = 0; col < num_cols; col++) {
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245 r = MAXJSAMPLE - GETJSAMPLE(inptr[0]);
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246 g = MAXJSAMPLE - GETJSAMPLE(inptr[1]);
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247 b = MAXJSAMPLE - GETJSAMPLE(inptr[2]);
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248 /* K passes through as-is */
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249 outptr3[col] = inptr[3]; /* don't need GETJSAMPLE here */
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250 inptr += 4;
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nuclear@1
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251 /* If the inputs are 0..MAXJSAMPLE, the outputs of these equations
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252 * must be too; we do not need an explicit range-limiting operation.
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253 * Hence the value being shifted is never negative, and we don't
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254 * need the general RIGHT_SHIFT macro.
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255 */
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nuclear@1
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256 /* Y */
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257 outptr0[col] = (JSAMPLE)
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nuclear@1
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258 ((ctab[r+R_Y_OFF] + ctab[g+G_Y_OFF] + ctab[b+B_Y_OFF])
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259 >> SCALEBITS);
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260 /* Cb */
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261 outptr1[col] = (JSAMPLE)
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nuclear@1
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262 ((ctab[r+R_CB_OFF] + ctab[g+G_CB_OFF] + ctab[b+B_CB_OFF])
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263 >> SCALEBITS);
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264 /* Cr */
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265 outptr2[col] = (JSAMPLE)
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nuclear@1
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266 ((ctab[r+R_CR_OFF] + ctab[g+G_CR_OFF] + ctab[b+B_CR_OFF])
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267 >> SCALEBITS);
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268 }
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269 }
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270 }
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271
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272
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273 /*
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nuclear@1
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274 * Convert some rows of samples to the JPEG colorspace.
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275 * This version handles grayscale output with no conversion.
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276 * The source can be either plain grayscale or YCbCr (since Y == gray).
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277 */
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278
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279 METHODDEF(void)
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280 grayscale_convert (j_compress_ptr cinfo,
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281 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
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282 JDIMENSION output_row, int num_rows)
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nuclear@1
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283 {
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284 register JSAMPROW inptr;
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nuclear@1
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285 register JSAMPROW outptr;
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nuclear@1
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286 register JDIMENSION col;
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nuclear@1
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287 JDIMENSION num_cols = cinfo->image_width;
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288 int instride = cinfo->input_components;
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289
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290 while (--num_rows >= 0) {
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291 inptr = *input_buf++;
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292 outptr = output_buf[0][output_row];
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293 output_row++;
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294 for (col = 0; col < num_cols; col++) {
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295 outptr[col] = inptr[0]; /* don't need GETJSAMPLE() here */
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296 inptr += instride;
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297 }
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298 }
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299 }
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300
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301
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nuclear@1
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302 /*
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nuclear@1
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303 * Convert some rows of samples to the JPEG colorspace.
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nuclear@1
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304 * This version handles multi-component colorspaces without conversion.
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305 * We assume input_components == num_components.
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nuclear@1
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306 */
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nuclear@1
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307
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nuclear@1
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308 METHODDEF(void)
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309 null_convert (j_compress_ptr cinfo,
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310 JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
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311 JDIMENSION output_row, int num_rows)
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nuclear@1
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312 {
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313 register JSAMPROW inptr;
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nuclear@1
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314 register JSAMPROW outptr;
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nuclear@1
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315 register JDIMENSION col;
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nuclear@1
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316 register int ci;
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317 int nc = cinfo->num_components;
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318 JDIMENSION num_cols = cinfo->image_width;
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319
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320 while (--num_rows >= 0) {
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nuclear@1
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321 /* It seems fastest to make a separate pass for each component. */
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322 for (ci = 0; ci < nc; ci++) {
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323 inptr = *input_buf;
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324 outptr = output_buf[ci][output_row];
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325 for (col = 0; col < num_cols; col++) {
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326 outptr[col] = inptr[ci]; /* don't need GETJSAMPLE() here */
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327 inptr += nc;
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328 }
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329 }
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330 input_buf++;
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331 output_row++;
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332 }
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333 }
|
nuclear@1
|
334
|
nuclear@1
|
335
|
nuclear@1
|
336 /*
|
nuclear@1
|
337 * Empty method for start_pass.
|
nuclear@1
|
338 */
|
nuclear@1
|
339
|
nuclear@1
|
340 METHODDEF(void)
|
nuclear@1
|
341 null_method (j_compress_ptr cinfo)
|
nuclear@1
|
342 {
|
nuclear@1
|
343 /* no work needed */
|
nuclear@1
|
344 }
|
nuclear@1
|
345
|
nuclear@1
|
346
|
nuclear@1
|
347 /*
|
nuclear@1
|
348 * Module initialization routine for input colorspace conversion.
|
nuclear@1
|
349 */
|
nuclear@1
|
350
|
nuclear@1
|
351 GLOBAL(void)
|
nuclear@1
|
352 jinit_color_converter (j_compress_ptr cinfo)
|
nuclear@1
|
353 {
|
nuclear@1
|
354 my_cconvert_ptr cconvert;
|
nuclear@1
|
355
|
nuclear@1
|
356 cconvert = (my_cconvert_ptr)
|
nuclear@1
|
357 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
|
nuclear@1
|
358 SIZEOF(my_color_converter));
|
nuclear@1
|
359 cinfo->cconvert = (struct jpeg_color_converter *) cconvert;
|
nuclear@1
|
360 /* set start_pass to null method until we find out differently */
|
nuclear@1
|
361 cconvert->pub.start_pass = null_method;
|
nuclear@1
|
362
|
nuclear@1
|
363 /* Make sure input_components agrees with in_color_space */
|
nuclear@1
|
364 switch (cinfo->in_color_space) {
|
nuclear@1
|
365 case JCS_GRAYSCALE:
|
nuclear@1
|
366 if (cinfo->input_components != 1)
|
nuclear@1
|
367 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
|
nuclear@1
|
368 break;
|
nuclear@1
|
369
|
nuclear@1
|
370 case JCS_RGB:
|
nuclear@1
|
371 #if RGB_PIXELSIZE != 3
|
nuclear@1
|
372 if (cinfo->input_components != RGB_PIXELSIZE)
|
nuclear@1
|
373 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
|
nuclear@1
|
374 break;
|
nuclear@1
|
375 #endif /* else share code with YCbCr */
|
nuclear@1
|
376
|
nuclear@1
|
377 case JCS_YCbCr:
|
nuclear@1
|
378 if (cinfo->input_components != 3)
|
nuclear@1
|
379 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
|
nuclear@1
|
380 break;
|
nuclear@1
|
381
|
nuclear@1
|
382 case JCS_CMYK:
|
nuclear@1
|
383 case JCS_YCCK:
|
nuclear@1
|
384 if (cinfo->input_components != 4)
|
nuclear@1
|
385 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
|
nuclear@1
|
386 break;
|
nuclear@1
|
387
|
nuclear@1
|
388 default: /* JCS_UNKNOWN can be anything */
|
nuclear@1
|
389 if (cinfo->input_components < 1)
|
nuclear@1
|
390 ERREXIT(cinfo, JERR_BAD_IN_COLORSPACE);
|
nuclear@1
|
391 break;
|
nuclear@1
|
392 }
|
nuclear@1
|
393
|
nuclear@1
|
394 /* Check num_components, set conversion method based on requested space */
|
nuclear@1
|
395 switch (cinfo->jpeg_color_space) {
|
nuclear@1
|
396 case JCS_GRAYSCALE:
|
nuclear@1
|
397 if (cinfo->num_components != 1)
|
nuclear@1
|
398 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
|
nuclear@1
|
399 if (cinfo->in_color_space == JCS_GRAYSCALE)
|
nuclear@1
|
400 cconvert->pub.color_convert = grayscale_convert;
|
nuclear@1
|
401 else if (cinfo->in_color_space == JCS_RGB) {
|
nuclear@1
|
402 cconvert->pub.start_pass = rgb_ycc_start;
|
nuclear@1
|
403 cconvert->pub.color_convert = rgb_gray_convert;
|
nuclear@1
|
404 } else if (cinfo->in_color_space == JCS_YCbCr)
|
nuclear@1
|
405 cconvert->pub.color_convert = grayscale_convert;
|
nuclear@1
|
406 else
|
nuclear@1
|
407 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
|
nuclear@1
|
408 break;
|
nuclear@1
|
409
|
nuclear@1
|
410 case JCS_RGB:
|
nuclear@1
|
411 if (cinfo->num_components != 3)
|
nuclear@1
|
412 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
|
nuclear@1
|
413 if (cinfo->in_color_space == JCS_RGB && RGB_PIXELSIZE == 3)
|
nuclear@1
|
414 cconvert->pub.color_convert = null_convert;
|
nuclear@1
|
415 else
|
nuclear@1
|
416 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
|
nuclear@1
|
417 break;
|
nuclear@1
|
418
|
nuclear@1
|
419 case JCS_YCbCr:
|
nuclear@1
|
420 if (cinfo->num_components != 3)
|
nuclear@1
|
421 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
|
nuclear@1
|
422 if (cinfo->in_color_space == JCS_RGB) {
|
nuclear@1
|
423 cconvert->pub.start_pass = rgb_ycc_start;
|
nuclear@1
|
424 cconvert->pub.color_convert = rgb_ycc_convert;
|
nuclear@1
|
425 } else if (cinfo->in_color_space == JCS_YCbCr)
|
nuclear@1
|
426 cconvert->pub.color_convert = null_convert;
|
nuclear@1
|
427 else
|
nuclear@1
|
428 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
|
nuclear@1
|
429 break;
|
nuclear@1
|
430
|
nuclear@1
|
431 case JCS_CMYK:
|
nuclear@1
|
432 if (cinfo->num_components != 4)
|
nuclear@1
|
433 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
|
nuclear@1
|
434 if (cinfo->in_color_space == JCS_CMYK)
|
nuclear@1
|
435 cconvert->pub.color_convert = null_convert;
|
nuclear@1
|
436 else
|
nuclear@1
|
437 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
|
nuclear@1
|
438 break;
|
nuclear@1
|
439
|
nuclear@1
|
440 case JCS_YCCK:
|
nuclear@1
|
441 if (cinfo->num_components != 4)
|
nuclear@1
|
442 ERREXIT(cinfo, JERR_BAD_J_COLORSPACE);
|
nuclear@1
|
443 if (cinfo->in_color_space == JCS_CMYK) {
|
nuclear@1
|
444 cconvert->pub.start_pass = rgb_ycc_start;
|
nuclear@1
|
445 cconvert->pub.color_convert = cmyk_ycck_convert;
|
nuclear@1
|
446 } else if (cinfo->in_color_space == JCS_YCCK)
|
nuclear@1
|
447 cconvert->pub.color_convert = null_convert;
|
nuclear@1
|
448 else
|
nuclear@1
|
449 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
|
nuclear@1
|
450 break;
|
nuclear@1
|
451
|
nuclear@1
|
452 default: /* allow null conversion of JCS_UNKNOWN */
|
nuclear@1
|
453 if (cinfo->jpeg_color_space != cinfo->in_color_space ||
|
nuclear@1
|
454 cinfo->num_components != cinfo->input_components)
|
nuclear@1
|
455 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
|
nuclear@1
|
456 cconvert->pub.color_convert = null_convert;
|
nuclear@1
|
457 break;
|
nuclear@1
|
458 }
|
nuclear@1
|
459 }
|