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2 | pj | 1 | /* |
2 | * fs4.c -- |
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3 | * |
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4 | * Procedures dealing with Floyd-Steinberg dithering with 4 error |
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5 | * values propagated. |
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6 | * |
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7 | */ |
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8 | |||
9 | /* |
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10 | * Copyright (c) 1995 The Regents of the University of California. |
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11 | * All rights reserved. |
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12 | * |
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13 | * Permission to use, copy, modify, and distribute this software and its |
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14 | * documentation for any purpose, without fee, and without written agreement is |
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15 | * hereby granted, provided that the above copyright notice and the following |
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16 | * two paragraphs appear in all copies of this software. |
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17 | * |
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18 | * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR |
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19 | * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT |
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20 | * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF |
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21 | * CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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22 | * |
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23 | * THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES, |
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24 | * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY |
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25 | * AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS |
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26 | * ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO |
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27 | * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. |
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28 | */ |
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29 | |||
30 | /* This file contains C code to do YCrCb -> colormap space. */ |
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31 | |||
32 | #include "fs4.h" |
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33 | #include "video.h" |
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34 | #include "proto.h" |
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35 | #include "dither.h" |
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36 | |||
37 | /* Structures containing precomputed error terms. */ |
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38 | |||
39 | static FS4Dither lum_index[256]; |
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40 | static FS4Dither cr_index[256]; |
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41 | static FS4Dither cb_index[256]; |
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42 | |||
43 | |||
44 | /* |
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45 | *-------------------------------------------------------------- |
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46 | * |
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47 | * InitFS4Dither -- |
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48 | * |
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49 | * Initializes structures used for f-s dithering. Precomputes |
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50 | * error terms. |
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51 | * |
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52 | * Results: |
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53 | * None. |
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54 | * |
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55 | * Side effects: |
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56 | * None. |
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57 | * |
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58 | *-------------------------------------------------------------- |
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59 | */ |
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60 | |||
61 | void |
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62 | InitFS4Dither() |
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63 | { |
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64 | int i; |
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65 | |||
66 | for (i=0; i<256; i++) { |
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67 | lum_index[i].value = (i * LUM_RANGE) / 256; |
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68 | |||
69 | lum_index[i].e1 = (7 * (i-lum_values[lum_index[i].value])) / 16; |
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70 | lum_index[i].e2 = (i-lum_values[lum_index[i].value])/16; |
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71 | lum_index[i].e3 = (5 * (i - lum_values[lum_index[i].value])) / 16; |
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72 | lum_index[i].e4 = (i-lum_values[lum_index[i].value]) - lum_index[i].e1 - |
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73 | lum_index[i].e2 - lum_index[i].e3; |
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74 | |||
75 | lum_index[i].value *= LUM_BASE; |
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76 | |||
77 | cr_index[i].value = (i * CR_RANGE) / 256; |
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78 | |||
79 | cr_index[i].e1 = (7 * (i-cr_values[cr_index[i].value])) / 16; |
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80 | cr_index[i].e2 = (i-cr_values[cr_index[i].value])/16; |
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81 | cr_index[i].e3 = (5 * (i - cr_values[cr_index[i].value])) / 16; |
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82 | cr_index[i].e4 = (i-cr_values[cr_index[i].value]) - cr_index[i].e1 - |
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83 | cr_index[i].e2 - cr_index[i].e3; |
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84 | cr_index[i].value *= CR_BASE; |
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85 | |||
86 | cb_index[i].value = (i * CB_RANGE) / 256; |
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87 | |||
88 | cb_index[i].e1 = (7 * (i-cb_values[cb_index[i].value])) / 16; |
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89 | cb_index[i].e2 = (i-cb_values[cb_index[i].value])/16; |
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90 | cb_index[i].e3 = (5 * (i - cb_values[cb_index[i].value])) / 16; |
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91 | cb_index[i].e4 = (i-cb_values[cb_index[i].value]) - cb_index[i].e1 - |
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92 | cb_index[i].e2 - cb_index[i].e3; |
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93 | cb_index[i].value *= CB_BASE; |
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94 | |||
95 | } |
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96 | |||
97 | } |
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98 | |||
99 | |||
100 | /* |
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101 | *-------------------------------------------------------------- |
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102 | * |
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103 | * DitherImage -- |
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104 | * |
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105 | * Converts lum, cr, cb image planes into fixed colormap |
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106 | * space. Uses Floyd-Steinberg dithering in serpentine |
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107 | * pattern with standard 4 errors propogated. |
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108 | * |
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109 | * Results: |
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110 | * The display plane is replaced by 8-bit colormap space |
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111 | * image. |
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112 | * |
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113 | * Side effects: |
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114 | * Hopefully, none. |
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115 | * |
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116 | *-------------------------------------------------------------- |
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117 | */ |
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118 | |||
119 | void |
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120 | FS4DitherImage(lum, cr, cb, disp, rows, cols) |
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121 | unsigned char *lum, *cr, *cb, *disp; |
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122 | int rows, cols; |
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123 | { |
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124 | static char *cur_row_error, *next_row_error; |
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125 | static int first = 1; |
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126 | char *cur_row_err_mark, *next_row_err_mark; |
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127 | char *temp; |
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128 | int i, j, pixsum, c_cols; |
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129 | unsigned char *cur_row, *channel, *dest_row; |
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130 | FS4Dither *chan_index; |
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131 | |||
132 | if (first) { |
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133 | cur_row_error = (char *) malloc(cols+2); |
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134 | next_row_error = (char *) malloc(cols+2); |
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135 | first = 0; |
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136 | } |
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137 | |||
138 | memset(cur_row_error, 0, cols+2); |
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139 | memset(next_row_error, 0, cols+2); |
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140 | |||
141 | for(i=0; i<rows; i+=2) { |
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142 | cur_row = lum + (i*cols); |
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143 | dest_row = disp + (i*cols); |
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144 | |||
145 | cur_row_err_mark = cur_row_error + 1; |
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146 | next_row_err_mark = next_row_error + 1; |
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147 | |||
148 | for (j=0; j<cols; j++) { |
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149 | |||
150 | pixsum = *cur_row + *cur_row_err_mark; |
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151 | if (pixsum < 0) pixsum = 0; |
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152 | else if (pixsum > 255) pixsum = 255; |
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153 | |||
154 | *dest_row = lum_index[pixsum].value; |
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155 | *(cur_row_err_mark+1) += lum_index[pixsum].e1; |
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156 | *(next_row_err_mark+1) += lum_index[pixsum].e2; |
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157 | *next_row_err_mark += lum_index[pixsum].e3; |
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158 | *(next_row_err_mark-1) += lum_index[pixsum].e4; |
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159 | |||
160 | cur_row++; |
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161 | dest_row++; |
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162 | cur_row_err_mark++; |
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163 | next_row_err_mark++; |
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164 | } |
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165 | |||
166 | temp = cur_row_error; |
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167 | cur_row_error = next_row_error; |
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168 | next_row_error = temp; |
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169 | |||
170 | memset(next_row_error, 0, cols+2); |
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171 | |||
172 | cur_row += cols-1; |
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173 | dest_row += cols-1; |
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174 | cur_row_err_mark = cur_row_error + cols; |
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175 | next_row_err_mark = next_row_error + cols; |
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176 | |||
177 | for (j=0; j<cols; j++) { |
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178 | |||
179 | pixsum = *cur_row + *cur_row_err_mark; |
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180 | if (pixsum < 0) pixsum = 0; |
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181 | else if (pixsum > 255) pixsum = 255; |
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182 | |||
183 | *dest_row = lum_index[pixsum].value; |
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184 | *(cur_row_err_mark-1) += lum_index[pixsum].e1; |
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185 | *(next_row_err_mark-1) += lum_index[pixsum].e2; |
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186 | *next_row_err_mark += lum_index[pixsum].e3; |
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187 | *(next_row_err_mark+1) += lum_index[pixsum].e4; |
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188 | |||
189 | cur_row--; |
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190 | dest_row--; |
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191 | cur_row_err_mark--; |
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192 | next_row_err_mark--; |
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193 | } |
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194 | |||
195 | temp = cur_row_error; |
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196 | cur_row_error = next_row_error; |
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197 | next_row_error = temp; |
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198 | |||
199 | memset(next_row_error, 0, cols+2); |
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200 | } |
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201 | |||
202 | memset(cur_row_error, 0, cols+2); |
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203 | |||
204 | c_cols = cols >> 1; |
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205 | |||
206 | channel = cr; |
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207 | chan_index = cr_index; |
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208 | |||
209 | repeat: |
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210 | |||
211 | for (i=0; i < rows; i+=2) { |
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212 | cur_row = channel + ((i>>1)*c_cols); |
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213 | dest_row = disp + (i*cols); |
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214 | |||
215 | cur_row_err_mark = cur_row_error+1; |
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216 | next_row_err_mark = next_row_error+1; |
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217 | |||
218 | for (j=0; j<cols; j++) { |
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219 | int p_val; |
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220 | |||
221 | p_val = *cur_row; |
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222 | |||
223 | pixsum = *cur_row_err_mark + p_val; |
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224 | |||
225 | if (pixsum < 0) pixsum = 0; |
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226 | else if (pixsum > 255) pixsum = 255; |
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227 | |||
228 | *dest_row += chan_index[pixsum].value; |
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229 | |||
230 | *(cur_row_err_mark+1) += chan_index[pixsum].e1; |
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231 | *(next_row_err_mark+1) += chan_index[pixsum].e2; |
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232 | *next_row_err_mark += chan_index[pixsum].e3; |
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233 | *(next_row_err_mark-1) += chan_index[pixsum].e4; |
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234 | |||
235 | |||
236 | if (j&1) cur_row++; |
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237 | dest_row++; |
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238 | cur_row_err_mark++; |
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239 | next_row_err_mark++; |
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240 | } |
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241 | |||
242 | temp = cur_row_error; |
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243 | cur_row_error = next_row_error; |
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244 | next_row_error = temp; |
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245 | |||
246 | memset(next_row_error, 0, cols+2); |
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247 | |||
248 | cur_row += c_cols-1; |
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249 | dest_row += cols-1; |
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250 | cur_row_err_mark = cur_row_error+cols; |
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251 | next_row_err_mark = next_row_error+cols; |
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252 | |||
253 | for (j=0; j<cols; j++) { |
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254 | int p_val; |
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255 | |||
256 | p_val = *cur_row; |
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257 | |||
258 | pixsum = *cur_row_err_mark + p_val; |
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259 | |||
260 | if (pixsum < 0) pixsum = 0; |
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261 | else if (pixsum > 255) pixsum = 255; |
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262 | |||
263 | *dest_row += chan_index[pixsum].value; |
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264 | |||
265 | *(cur_row_err_mark-1) += chan_index[pixsum].e1; |
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266 | *(next_row_err_mark-1) += chan_index[pixsum].e2; |
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267 | *next_row_err_mark += chan_index[pixsum].e3; |
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268 | *(next_row_err_mark+1) += chan_index[pixsum].e4; |
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269 | |||
270 | if (j&1) cur_row--; |
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271 | dest_row--; |
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272 | cur_row_err_mark--; |
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273 | next_row_err_mark--; |
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274 | } |
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275 | |||
276 | temp = cur_row_error; |
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277 | cur_row_error = next_row_error; |
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278 | next_row_error = temp; |
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279 | |||
280 | memset(next_row_error, 0, cols+2); |
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281 | } |
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282 | |||
283 | if (channel == cr) { |
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284 | channel = cb; |
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285 | chan_index = cb_index; |
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286 | memset(cur_row_error, 0, cols+2); |
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287 | |||
288 | goto repeat; |
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289 | } |
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290 | |||
291 | dest_row = disp; |
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292 | |||
293 | |||
294 | for (i=0; i<rows; i++) { |
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295 | for (j=0; j<cols; j++) { |
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296 | *dest_row = pixel[*dest_row]; |
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297 | dest_row++; |
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298 | } |
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299 | } |
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300 | } |