1 | /* |
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2 | * libpipi Pathetic image processing interface library |
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3 | * Copyright (c) 2004-2008 Sam Hocevar <sam@zoy.org> |
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4 | * All Rights Reserved |
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5 | * |
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6 | * $Id$ |
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7 | * |
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8 | * This library is free software. It comes without any warranty, to |
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9 | * the extent permitted by applicable law. You can redistribute it |
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10 | * and/or modify it under the terms of the Do What The Fuck You Want |
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11 | * To Public License, Version 2, as published by Sam Hocevar. See |
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12 | * http://sam.zoy.org/wtfpl/COPYING for more details. |
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13 | */ |
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14 | |
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15 | /* |
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16 | * ordered.c: Bayer ordered dithering functions |
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17 | */ |
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18 | |
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19 | #include "config.h" |
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20 | #include "common.h" |
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21 | |
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22 | #include <stdlib.h> |
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23 | #include <math.h> |
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24 | |
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25 | #include "pipi.h" |
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26 | #include "pipi_internals.h" |
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27 | |
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28 | pipi_image_t *pipi_dither_halftone(pipi_image_t *img, double r, double angle) |
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29 | { |
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30 | #define PRECISION 4. |
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31 | pipi_image_t *ret, *kernel; |
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32 | int k = (r * PRECISION / 2. / sqrt(2.) + .5); |
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33 | |
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34 | kernel = pipi_render_halftone(k, k); |
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35 | ret = pipi_dither_ordered_ext(img, kernel, 1. / PRECISION, angle + 45.); |
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36 | pipi_free(kernel); |
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37 | |
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38 | return ret; |
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39 | } |
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40 | |
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41 | pipi_image_t *pipi_dither_ordered(pipi_image_t *img, pipi_image_t *kernel) |
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42 | { |
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43 | return pipi_dither_ordered_ext(img, kernel, 1.0, 0.0); |
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44 | } |
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45 | |
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46 | pipi_image_t *pipi_dither_ordered_ext(pipi_image_t *img, pipi_image_t *kernel, |
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47 | double scale, double angle) |
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48 | { |
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49 | double sint, cost; |
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50 | pipi_image_t *dst; |
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51 | pipi_pixels_t *dstp, *kernelp; |
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52 | float *dstdata, *kerneldata; |
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53 | int x, y, w, h, kx, ky, kw, kh; |
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54 | |
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55 | w = img->w; |
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56 | h = img->h; |
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57 | kw = kernel->w; |
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58 | kh = kernel->h; |
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59 | |
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60 | cost = cos(angle * (M_PI / 180)); |
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61 | sint = sin(angle * (M_PI / 180)); |
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62 | |
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63 | dst = pipi_copy(img); |
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64 | dstp = pipi_getpixels(dst, PIPI_PIXELS_Y_F); |
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65 | dstdata = (float *)dstp->pixels; |
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66 | |
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67 | kernelp = pipi_getpixels(kernel, PIPI_PIXELS_Y_F); |
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68 | kerneldata = (float *)kernelp->pixels; |
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69 | |
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70 | for(y = 0; y < h; y++) |
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71 | { |
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72 | for(x = 0; x < w; x++) |
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73 | { |
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74 | float p, q; |
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75 | |
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76 | kx = (int)((cost * x - sint * y + 2 * w * h) / scale) % kw; |
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77 | ky = (int)((cost * y + sint * x + 2 * w * h) / scale) % kh; |
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78 | |
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79 | p = dstdata[y * w + x]; |
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80 | q = p > kerneldata[ky * kw + kx] ? 1. : 0.; |
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81 | dstdata[y * w + x] = q; |
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82 | } |
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83 | } |
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84 | |
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85 | return dst; |
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86 | } |
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87 | |
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88 | typedef struct |
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89 | { |
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90 | int x, y; |
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91 | double val; |
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92 | } |
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93 | dot_t; |
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94 | |
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95 | static int cmpdot(const void *p1, const void *p2) |
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96 | { |
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97 | return ((dot_t const *)p1)->val > ((dot_t const *)p2)->val; |
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98 | } |
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99 | |
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100 | pipi_image_t *pipi_order(pipi_image_t *src) |
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101 | { |
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102 | double epsilon; |
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103 | pipi_image_t *dst; |
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104 | pipi_pixels_t *dstp, *srcp; |
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105 | float *dstdata, *srcdata; |
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106 | dot_t *circle; |
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107 | int x, y, w, h, n; |
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108 | |
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109 | w = src->w; |
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110 | h = src->h; |
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111 | epsilon = 1. / (w * h + 1); |
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112 | |
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113 | srcp = pipi_getpixels(src, PIPI_PIXELS_Y_F); |
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114 | srcdata = (float *)srcp->pixels; |
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115 | |
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116 | dst = pipi_new(w, h); |
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117 | dstp = pipi_getpixels(dst, PIPI_PIXELS_Y_F); |
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118 | dstdata = (float *)dstp->pixels; |
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119 | |
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120 | circle = malloc(w * h * sizeof(dot_t)); |
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121 | |
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122 | for(y = 0; y < h; y++) |
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123 | for(x = 0; x < w; x++) |
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124 | { |
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125 | circle[y * w + x].x = x; |
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126 | circle[y * w + x].y = y; |
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127 | circle[y * w + x].val = srcdata[y * w + x]; |
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128 | } |
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129 | qsort(circle, w * h, sizeof(dot_t), cmpdot); |
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130 | |
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131 | for(n = 0; n < w * h; n++) |
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132 | { |
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133 | x = circle[n].x; |
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134 | y = circle[n].y; |
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135 | dstdata[y * w + x] = (float)(n + 1) * epsilon; |
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136 | } |
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137 | |
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138 | free(circle); |
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139 | |
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140 | return dst; |
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141 | } |
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142 | |
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