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1 /* |
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2 * jdmerge.c |
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3 * |
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4 * Copyright (C) 1994-1996, 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 code for merged upsampling/color conversion. |
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9 * |
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10 * This file combines functions from jdsample.c and jdcolor.c; |
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11 * read those files first to understand what's going on. |
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12 * |
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13 * When the chroma components are to be upsampled by simple replication |
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14 * (ie, box filtering), we can save some work in color conversion by |
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15 * calculating all the output pixels corresponding to a pair of chroma |
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16 * samples at one time. In the conversion equations |
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17 * R = Y + K1 * Cr |
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18 * G = Y + K2 * Cb + K3 * Cr |
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19 * B = Y + K4 * Cb |
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20 * only the Y term varies among the group of pixels corresponding to a pair |
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21 * of chroma samples, so the rest of the terms can be calculated just once. |
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22 * At typical sampling ratios, this eliminates half or three-quarters of the |
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23 * multiplications needed for color conversion. |
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24 * |
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25 * This file currently provides implementations for the following cases: |
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26 * YCbCr => RGB color conversion only. |
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27 * Sampling ratios of 2h1v or 2h2v. |
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28 * No scaling needed at upsample time. |
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29 * Corner-aligned (non-CCIR601) sampling alignment. |
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30 * Other special cases could be added, but in most applications these are |
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31 * the only common cases. (For uncommon cases we fall back on the more |
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32 * general code in jdsample.c and jdcolor.c.) |
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33 */ |
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34 |
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35 #define JPEG_INTERNALS |
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36 #include "jinclude.h" |
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37 #include "jpeglib.h" |
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38 |
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39 #ifdef UPSAMPLE_MERGING_SUPPORTED |
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40 |
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41 |
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42 /* Private subobject */ |
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43 |
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44 typedef struct { |
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45 struct jpeg_upsampler pub; /* public fields */ |
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46 |
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47 /* Pointer to routine to do actual upsampling/conversion of one row group */ |
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48 JMETHOD(void, upmethod, (j_decompress_ptr cinfo, |
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49 JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr, |
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50 JSAMPARRAY output_buf)); |
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51 |
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52 /* Private state for YCC->RGB conversion */ |
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53 int * Cr_r_tab; /* => table for Cr to R conversion */ |
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54 int * Cb_b_tab; /* => table for Cb to B conversion */ |
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55 INT32 * Cr_g_tab; /* => table for Cr to G conversion */ |
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56 INT32 * Cb_g_tab; /* => table for Cb to G conversion */ |
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57 |
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58 /* For 2:1 vertical sampling, we produce two output rows at a time. |
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59 * We need a "spare" row buffer to hold the second output row if the |
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60 * application provides just a one-row buffer; we also use the spare |
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61 * to discard the dummy last row if the image height is odd. |
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62 */ |
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63 JSAMPROW spare_row; |
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64 boolean spare_full; /* T if spare buffer is occupied */ |
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65 |
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66 JDIMENSION out_row_width; /* samples per output row */ |
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67 JDIMENSION rows_to_go; /* counts rows remaining in image */ |
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68 } my_upsampler; |
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69 |
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70 typedef my_upsampler * my_upsample_ptr; |
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71 |
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72 #define SCALEBITS 16 /* speediest right-shift on some machines */ |
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73 #define ONE_HALF ((INT32) 1 << (SCALEBITS-1)) |
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74 #define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5)) |
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75 |
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76 |
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77 /* |
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78 * Initialize tables for YCC->RGB colorspace conversion. |
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79 * This is taken directly from jdcolor.c; see that file for more info. |
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80 */ |
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81 |
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82 LOCAL(void) |
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83 build_ycc_rgb_table (j_decompress_ptr cinfo) |
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84 { |
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85 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; |
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86 int i; |
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87 INT32 x; |
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88 SHIFT_TEMPS |
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89 |
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90 upsample->Cr_r_tab = (int *) |
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91 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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92 (MAXJSAMPLE+1) * SIZEOF(int)); |
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93 upsample->Cb_b_tab = (int *) |
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94 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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95 (MAXJSAMPLE+1) * SIZEOF(int)); |
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96 upsample->Cr_g_tab = (INT32 *) |
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97 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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98 (MAXJSAMPLE+1) * SIZEOF(INT32)); |
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99 upsample->Cb_g_tab = (INT32 *) |
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100 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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101 (MAXJSAMPLE+1) * SIZEOF(INT32)); |
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102 |
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103 for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) { |
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104 /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */ |
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105 /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */ |
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106 /* Cr=>R value is nearest int to 1.40200 * x */ |
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107 upsample->Cr_r_tab[i] = (int) |
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108 RIGHT_SHIFT(FIX(1.40200) * x + ONE_HALF, SCALEBITS); |
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109 /* Cb=>B value is nearest int to 1.77200 * x */ |
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110 upsample->Cb_b_tab[i] = (int) |
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111 RIGHT_SHIFT(FIX(1.77200) * x + ONE_HALF, SCALEBITS); |
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112 /* Cr=>G value is scaled-up -0.71414 * x */ |
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113 upsample->Cr_g_tab[i] = (- FIX(0.71414)) * x; |
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114 /* Cb=>G value is scaled-up -0.34414 * x */ |
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115 /* We also add in ONE_HALF so that need not do it in inner loop */ |
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116 upsample->Cb_g_tab[i] = (- FIX(0.34414)) * x + ONE_HALF; |
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117 } |
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118 } |
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119 |
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120 |
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121 /* |
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122 * Initialize for an upsampling pass. |
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123 */ |
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124 |
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125 METHODDEF(void) |
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126 start_pass_merged_upsample (j_decompress_ptr cinfo) |
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127 { |
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128 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; |
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129 |
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130 /* Mark the spare buffer empty */ |
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131 upsample->spare_full = FALSE; |
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132 /* Initialize total-height counter for detecting bottom of image */ |
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133 upsample->rows_to_go = cinfo->output_height; |
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134 } |
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135 |
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136 |
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137 /* |
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138 * Control routine to do upsampling (and color conversion). |
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139 * |
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140 * The control routine just handles the row buffering considerations. |
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141 */ |
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142 |
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143 METHODDEF(void) |
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144 merged_2v_upsample (j_decompress_ptr cinfo, |
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145 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, |
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146 JDIMENSION in_row_groups_avail, |
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147 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, |
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148 JDIMENSION out_rows_avail) |
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149 /* 2:1 vertical sampling case: may need a spare row. */ |
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150 { |
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151 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; |
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152 JSAMPROW work_ptrs[2]; |
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153 JDIMENSION num_rows; /* number of rows returned to caller */ |
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154 |
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155 if (upsample->spare_full) { |
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156 /* If we have a spare row saved from a previous cycle, just return it. */ |
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157 jcopy_sample_rows(& upsample->spare_row, 0, output_buf + *out_row_ctr, 0, |
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158 1, upsample->out_row_width); |
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159 num_rows = 1; |
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160 upsample->spare_full = FALSE; |
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161 } else { |
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162 /* Figure number of rows to return to caller. */ |
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163 num_rows = 2; |
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164 /* Not more than the distance to the end of the image. */ |
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165 if (num_rows > upsample->rows_to_go) |
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166 num_rows = upsample->rows_to_go; |
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167 /* And not more than what the client can accept: */ |
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168 out_rows_avail -= *out_row_ctr; |
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169 if (num_rows > out_rows_avail) |
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170 num_rows = out_rows_avail; |
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171 /* Create output pointer array for upsampler. */ |
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172 work_ptrs[0] = output_buf[*out_row_ctr]; |
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173 if (num_rows > 1) { |
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174 work_ptrs[1] = output_buf[*out_row_ctr + 1]; |
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175 } else { |
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176 work_ptrs[1] = upsample->spare_row; |
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177 upsample->spare_full = TRUE; |
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178 } |
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179 /* Now do the upsampling. */ |
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180 (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr, work_ptrs); |
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181 } |
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182 |
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183 /* Adjust counts */ |
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184 *out_row_ctr += num_rows; |
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185 upsample->rows_to_go -= num_rows; |
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186 /* When the buffer is emptied, declare this input row group consumed */ |
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187 if (! upsample->spare_full) |
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188 (*in_row_group_ctr)++; |
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189 } |
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190 |
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191 |
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192 METHODDEF(void) |
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193 merged_1v_upsample (j_decompress_ptr cinfo, |
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194 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, |
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195 JDIMENSION in_row_groups_avail, |
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196 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, |
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197 JDIMENSION out_rows_avail) |
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198 /* 1:1 vertical sampling case: much easier, never need a spare row. */ |
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199 { |
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200 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; |
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201 |
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202 /* Just do the upsampling. */ |
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203 (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr, |
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204 output_buf + *out_row_ctr); |
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205 /* Adjust counts */ |
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206 (*out_row_ctr)++; |
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207 (*in_row_group_ctr)++; |
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208 } |
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209 |
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210 |
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211 /* |
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212 * These are the routines invoked by the control routines to do |
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213 * the actual upsampling/conversion. One row group is processed per call. |
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214 * |
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215 * Note: since we may be writing directly into application-supplied buffers, |
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216 * we have to be honest about the output width; we can't assume the buffer |
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217 * has been rounded up to an even width. |
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218 */ |
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219 |
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220 |
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221 /* |
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222 * Upsample and color convert for the case of 2:1 horizontal and 1:1 vertical. |
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223 */ |
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224 |
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225 METHODDEF(void) |
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226 h2v1_merged_upsample (j_decompress_ptr cinfo, |
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227 JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr, |
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228 JSAMPARRAY output_buf) |
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229 { |
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230 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; |
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231 register int y, cred, cgreen, cblue; |
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232 int cb, cr; |
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233 register JSAMPROW outptr; |
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234 JSAMPROW inptr0, inptr1, inptr2; |
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235 JDIMENSION col; |
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236 /* copy these pointers into registers if possible */ |
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237 register JSAMPLE * range_limit = cinfo->sample_range_limit; |
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238 int * Crrtab = upsample->Cr_r_tab; |
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239 int * Cbbtab = upsample->Cb_b_tab; |
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240 INT32 * Crgtab = upsample->Cr_g_tab; |
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241 INT32 * Cbgtab = upsample->Cb_g_tab; |
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242 SHIFT_TEMPS |
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243 |
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244 inptr0 = input_buf[0][in_row_group_ctr]; |
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245 inptr1 = input_buf[1][in_row_group_ctr]; |
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246 inptr2 = input_buf[2][in_row_group_ctr]; |
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247 outptr = output_buf[0]; |
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248 /* Loop for each pair of output pixels */ |
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249 for (col = cinfo->output_width >> 1; col > 0; col--) { |
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250 /* Do the chroma part of the calculation */ |
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251 cb = GETJSAMPLE(*inptr1++); |
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252 cr = GETJSAMPLE(*inptr2++); |
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253 cred = Crrtab[cr]; |
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254 cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS); |
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255 cblue = Cbbtab[cb]; |
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256 /* Fetch 2 Y values and emit 2 pixels */ |
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257 y = GETJSAMPLE(*inptr0++); |
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258 outptr[RGB_RED] = range_limit[y + cred]; |
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259 outptr[RGB_GREEN] = range_limit[y + cgreen]; |
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260 outptr[RGB_BLUE] = range_limit[y + cblue]; |
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261 outptr += RGB_PIXELSIZE; |
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262 y = GETJSAMPLE(*inptr0++); |
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263 outptr[RGB_RED] = range_limit[y + cred]; |
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264 outptr[RGB_GREEN] = range_limit[y + cgreen]; |
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265 outptr[RGB_BLUE] = range_limit[y + cblue]; |
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266 outptr += RGB_PIXELSIZE; |
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267 } |
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268 /* If image width is odd, do the last output column separately */ |
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269 if (cinfo->output_width & 1) { |
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270 cb = GETJSAMPLE(*inptr1); |
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271 cr = GETJSAMPLE(*inptr2); |
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272 cred = Crrtab[cr]; |
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273 cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS); |
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274 cblue = Cbbtab[cb]; |
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275 y = GETJSAMPLE(*inptr0); |
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276 outptr[RGB_RED] = range_limit[y + cred]; |
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277 outptr[RGB_GREEN] = range_limit[y + cgreen]; |
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278 outptr[RGB_BLUE] = range_limit[y + cblue]; |
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279 } |
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280 } |
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281 |
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282 |
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283 /* |
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284 * Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical. |
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285 */ |
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286 |
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287 METHODDEF(void) |
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288 h2v2_merged_upsample (j_decompress_ptr cinfo, |
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289 JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr, |
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290 JSAMPARRAY output_buf) |
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291 { |
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292 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample; |
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293 register int y, cred, cgreen, cblue; |
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294 int cb, cr; |
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295 register JSAMPROW outptr0, outptr1; |
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296 JSAMPROW inptr00, inptr01, inptr1, inptr2; |
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297 JDIMENSION col; |
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298 /* copy these pointers into registers if possible */ |
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299 register JSAMPLE * range_limit = cinfo->sample_range_limit; |
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300 int * Crrtab = upsample->Cr_r_tab; |
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301 int * Cbbtab = upsample->Cb_b_tab; |
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302 INT32 * Crgtab = upsample->Cr_g_tab; |
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303 INT32 * Cbgtab = upsample->Cb_g_tab; |
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304 SHIFT_TEMPS |
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305 |
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306 inptr00 = input_buf[0][in_row_group_ctr*2]; |
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307 inptr01 = input_buf[0][in_row_group_ctr*2 + 1]; |
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308 inptr1 = input_buf[1][in_row_group_ctr]; |
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309 inptr2 = input_buf[2][in_row_group_ctr]; |
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310 outptr0 = output_buf[0]; |
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311 outptr1 = output_buf[1]; |
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312 /* Loop for each group of output pixels */ |
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313 for (col = cinfo->output_width >> 1; col > 0; col--) { |
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314 /* Do the chroma part of the calculation */ |
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315 cb = GETJSAMPLE(*inptr1++); |
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316 cr = GETJSAMPLE(*inptr2++); |
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317 cred = Crrtab[cr]; |
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318 cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS); |
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319 cblue = Cbbtab[cb]; |
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320 /* Fetch 4 Y values and emit 4 pixels */ |
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321 y = GETJSAMPLE(*inptr00++); |
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322 outptr0[RGB_RED] = range_limit[y + cred]; |
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323 outptr0[RGB_GREEN] = range_limit[y + cgreen]; |
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324 outptr0[RGB_BLUE] = range_limit[y + cblue]; |
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325 outptr0 += RGB_PIXELSIZE; |
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326 y = GETJSAMPLE(*inptr00++); |
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327 outptr0[RGB_RED] = range_limit[y + cred]; |
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328 outptr0[RGB_GREEN] = range_limit[y + cgreen]; |
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329 outptr0[RGB_BLUE] = range_limit[y + cblue]; |
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330 outptr0 += RGB_PIXELSIZE; |
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331 y = GETJSAMPLE(*inptr01++); |
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332 outptr1[RGB_RED] = range_limit[y + cred]; |
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333 outptr1[RGB_GREEN] = range_limit[y + cgreen]; |
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334 outptr1[RGB_BLUE] = range_limit[y + cblue]; |
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335 outptr1 += RGB_PIXELSIZE; |
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336 y = GETJSAMPLE(*inptr01++); |
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337 outptr1[RGB_RED] = range_limit[y + cred]; |
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338 outptr1[RGB_GREEN] = range_limit[y + cgreen]; |
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339 outptr1[RGB_BLUE] = range_limit[y + cblue]; |
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340 outptr1 += RGB_PIXELSIZE; |
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341 } |
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342 /* If image width is odd, do the last output column separately */ |
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343 if (cinfo->output_width & 1) { |
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344 cb = GETJSAMPLE(*inptr1); |
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345 cr = GETJSAMPLE(*inptr2); |
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346 cred = Crrtab[cr]; |
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347 cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS); |
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348 cblue = Cbbtab[cb]; |
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349 y = GETJSAMPLE(*inptr00); |
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350 outptr0[RGB_RED] = range_limit[y + cred]; |
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351 outptr0[RGB_GREEN] = range_limit[y + cgreen]; |
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352 outptr0[RGB_BLUE] = range_limit[y + cblue]; |
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353 y = GETJSAMPLE(*inptr01); |
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354 outptr1[RGB_RED] = range_limit[y + cred]; |
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355 outptr1[RGB_GREEN] = range_limit[y + cgreen]; |
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356 outptr1[RGB_BLUE] = range_limit[y + cblue]; |
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357 } |
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358 } |
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359 |
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360 |
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361 /* |
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362 * Module initialization routine for merged upsampling/color conversion. |
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363 * |
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364 * NB: this is called under the conditions determined by use_merged_upsample() |
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365 * in jdmaster.c. That routine MUST correspond to the actual capabilities |
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366 * of this module; no safety checks are made here. |
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367 */ |
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368 |
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369 GLOBAL(void) |
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370 jinit_merged_upsampler (j_decompress_ptr cinfo) |
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371 { |
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372 my_upsample_ptr upsample; |
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373 |
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374 upsample = (my_upsample_ptr) |
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375 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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376 SIZEOF(my_upsampler)); |
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377 cinfo->upsample = (struct jpeg_upsampler *) upsample; |
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378 upsample->pub.start_pass = start_pass_merged_upsample; |
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379 upsample->pub.need_context_rows = FALSE; |
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380 |
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381 upsample->out_row_width = cinfo->output_width * cinfo->out_color_components; |
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382 |
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383 if (cinfo->max_v_samp_factor == 2) { |
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384 upsample->pub.upsample = merged_2v_upsample; |
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385 upsample->upmethod = h2v2_merged_upsample; |
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386 /* Allocate a spare row buffer */ |
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387 upsample->spare_row = (JSAMPROW) |
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388 (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
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389 (size_t) (upsample->out_row_width * SIZEOF(JSAMPLE))); |
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390 } else { |
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391 upsample->pub.upsample = merged_1v_upsample; |
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392 upsample->upmethod = h2v1_merged_upsample; |
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393 /* No spare row needed */ |
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394 upsample->spare_row = NULL; |
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395 } |
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396 |
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397 build_ycc_rgb_table(cinfo); |
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398 } |
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399 |
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400 #endif /* UPSAMPLE_MERGING_SUPPORTED */ |