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1 <!-- Creator : groff version 1.18.1 --> |
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2 <!-- CreationDate: Mon Mar 13 18:03:10 2006 --> |
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3 <html> |
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4 <head> |
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5 <meta name="generator" content="groff -Thtml, see www.gnu.org"> |
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6 <meta name="Content-Style" content="text/css"> |
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7 <title>TIFFRGBAImage</title> |
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8 </head> |
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9 <body> |
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10 |
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11 <h1 align=center>TIFFRGBAImage</h1> |
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12 <a href="#NAME">NAME</a><br> |
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13 <a href="#SYNOPSIS">SYNOPSIS</a><br> |
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14 <a href="#DESCRIPTION">DESCRIPTION</a><br> |
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15 <a href="#ALTERNATE RASTER FORMATS">ALTERNATE RASTER FORMATS</a><br> |
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16 <a href="#SIMULTANEOUS RASTER STORE AND DISPLAY">SIMULTANEOUS RASTER STORE AND DISPLAY</a><br> |
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17 <a href="#SUPPORTING ADDITIONAL TIFF FORMATS">SUPPORTING ADDITIONAL TIFF FORMATS</a><br> |
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18 <a href="#NOTES">NOTES</a><br> |
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19 <a href="#RETURN VALUES">RETURN VALUES</a><br> |
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20 <a href="#DIAGNOSTICS">DIAGNOSTICS</a><br> |
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21 <a href="#SEE ALSO">SEE ALSO</a><br> |
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22 |
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23 <hr> |
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24 <a name="NAME"></a> |
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25 <h2>NAME</h2> |
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26 <!-- INDENTATION --> |
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27 <table width="100%" border=0 rules="none" frame="void" |
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28 cols="2" cellspacing="0" cellpadding="0"> |
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29 <tr valign="top" align="left"> |
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30 <td width="8%"></td> |
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31 <td width="91%"> |
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32 <p>TIFFRGBAImageOK, TIFFRGBAImageBegin, TIFFRGBAImageGet, |
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33 TIFFRGBAImageEnd − read and decode an image into a |
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34 raster</p> |
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35 </td> |
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36 </table> |
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37 <a name="SYNOPSIS"></a> |
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38 <h2>SYNOPSIS</h2> |
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39 <!-- INDENTATION --> |
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40 <table width="100%" border=0 rules="none" frame="void" |
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41 cols="2" cellspacing="0" cellpadding="0"> |
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42 <tr valign="top" align="left"> |
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43 <td width="8%"></td> |
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44 <td width="91%"> |
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45 <p><b>#include <tiffio.h></b></p> |
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46 <!-- INDENTATION --> |
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47 <p><b>typedef unsigned char TIFFRGBValue; typedef struct |
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48 _TIFFRGBAImage TIFFRGBAImage;</b></p> |
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49 <!-- INDENTATION --> |
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50 <p><b>int TIFFRGBAImageOK(TIFF *</b><i>tif</i><b>, char</b> |
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51 <i>emsg[1024]</i><b>)<br> |
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52 int TIFFRGBAImageBegin(TIFFRGBAImage *</b><i>img</i><b>, |
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53 TIFF*</b> <i>tif</i><b>, int</b> <i>stopOnError</i><b>, |
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54 char</b> <i>emsg[1024]</i><b>)<br> |
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55 int TIFFRGBAImageGet(TIFFRGBAImage *</b><i>img</i><b>, |
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56 uint32*</b> <i>raster</i><b>, uint32</b> <i>width</i> <b>, |
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57 uint32</b> <i>height</i><b>)<br> |
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58 void TIFFRGBAImageEnd(TIFFRGBAImage |
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59 *</b><i>img</i><b>)</b></p> |
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60 </td> |
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61 </table> |
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62 <a name="DESCRIPTION"></a> |
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63 <h2>DESCRIPTION</h2> |
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64 <!-- INDENTATION --> |
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65 <table width="100%" border=0 rules="none" frame="void" |
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66 cols="2" cellspacing="0" cellpadding="0"> |
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67 <tr valign="top" align="left"> |
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68 <td width="8%"></td> |
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69 <td width="91%"> |
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70 <p>The routines described here provide a high-level |
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71 interface through which <small>TIFF</small> images may be |
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72 read into memory. Images may be strip- or tile-based and |
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73 have a variety of different characteristics: bits/sample, |
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74 samples/pixel, photometric, etc. Decoding state is |
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75 encapsulated in a <i>TIFFRGBAImage</i> structure making it |
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76 possible to capture state for multiple images and quickly |
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77 switch between them. The target raster format can be |
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78 customized to a particular application’s needs by |
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79 installing custom routines that manipulate image data |
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80 according to application requirements.</p> |
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81 <!-- INDENTATION --> |
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82 <p>The default usage for these routines is: check if an |
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83 image can be processed using <i>TIFFRGBAImageOK</i>, |
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84 construct a decoder state block using |
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85 <i>TIFFRGBAImageBegin</i>, read and decode an image into a |
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86 target raster using <i>TIFFRGBAImageGet</i>, and then |
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87 release resources using <i>TIFFRGBAImageEnd</i>. |
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88 <i>TIFFRGBAImageGet</i> can be called multiple times to |
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89 decode an image using different state parameters. If |
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90 multiple images are to be displayed and there is not enough |
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91 space for each of the decoded rasters, multiple state blocks |
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92 can be managed and then calls can be made to |
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93 <i>TIFFRGBAImageGet</i> as needed to display an image.</p> |
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94 <!-- INDENTATION --> |
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95 <p>The generated raster is assumed to be an array of |
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96 <i>width</i> times <i>height</i> 32-bit entries, where |
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97 <i>width</i> must be less than or equal to the width of the |
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98 image (<i>height</i> may be any non-zero size). If the |
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99 raster dimensions are smaller than the image, the image data |
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100 is cropped to the raster bounds. If the raster height is |
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101 greater than that of the image, then the image data are |
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102 placed in the lower part of the raster. (Note that the |
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103 raster is assume to be organized such that the pixel at |
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104 location (<i>x</i>,<i>y</i>) is |
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105 <i>raster</i>[<i>y</i>*<i>width</i>+<i>x</i>]; with the |
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106 raster origin in the <b>lower-left</b> hand corner.)</p> |
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107 <!-- INDENTATION --> |
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108 <p>Raster pixels are 8-bit packed red, green, blue, alpha |
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109 samples. The macros <i>TIFFGetR</i>, <i>TIFFGetG</i>, |
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110 <i>TIFFGetB</i>, and <i>TIFFGetA</i> should be used to |
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111 access individual samples. Images without Associated Alpha |
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112 matting information have a constant Alpha of 1.0 (255).</p> |
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113 <!-- INDENTATION --> |
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114 <p><i>TIFFRGBAImageGet</i> converts non-8-bit images by |
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115 scaling sample values. Palette, grayscale, bilevel, |
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116 <small>CMYK</small> , and YCbCr images are converted to |
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117 <small>RGB</small> transparently. Raster pixels are returned |
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118 uncorrected by any colorimetry information present in the |
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119 directory.</p> |
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120 <!-- INDENTATION --> |
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121 <p>The parameter <i>stopOnError</i> specifies how to act if |
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122 an error is encountered while reading the image. If |
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123 <i>stopOnError</i> is non-zero, then an error will terminate |
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124 the operation; otherwise <i>TIFFRGBAImageGet</i> will |
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125 continue processing data until all the possible data in the |
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126 image have been requested.</p> |
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127 </td> |
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128 </table> |
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129 <a name="ALTERNATE RASTER FORMATS"></a> |
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130 <h2>ALTERNATE RASTER FORMATS</h2> |
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131 <!-- INDENTATION --> |
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132 <table width="100%" border=0 rules="none" frame="void" |
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133 cols="2" cellspacing="0" cellpadding="0"> |
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134 <tr valign="top" align="left"> |
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135 <td width="8%"></td> |
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136 <td width="91%"> |
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137 <p>To use the core support for reading and processing |
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138 <small>TIFF</small> images, but write the resulting raster |
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139 data in a different format one need only override the |
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140 ‘‘<i>put methods</i>’’ used to store |
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141 raster data. These methods are are defined in the |
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142 <i>TIFFRGBAImage</i> structure and initially setup by |
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143 <i>TIFFRGBAImageBegin</i> to point to routines that pack |
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144 raster data in the default <small>ABGR</small> pixel format. |
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145 Two different routines are used according to the physical |
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146 organization of the image data in the file: |
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147 <i>PlanarConfiguration</i>=1 (packed samples), and |
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148 <i>PlanarConfiguration</i>=2 (separated samples). Note that |
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149 this mechanism can be used to transform the data before |
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150 storing it in the raster. For example one can convert data |
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151 to colormap indices for display on a colormap display.</p> |
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152 </td> |
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153 </table> |
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154 <a name="SIMULTANEOUS RASTER STORE AND DISPLAY"></a> |
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155 <h2>SIMULTANEOUS RASTER STORE AND DISPLAY</h2> |
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156 <!-- INDENTATION --> |
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157 <table width="100%" border=0 rules="none" frame="void" |
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158 cols="2" cellspacing="0" cellpadding="0"> |
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159 <tr valign="top" align="left"> |
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160 <td width="8%"></td> |
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161 <td width="91%"> |
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162 <p>It is simple to display an image as it is being read into |
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163 memory by overriding the put methods as described above for |
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164 supporting alternate raster formats. Simply keep a reference |
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165 to the default put methods setup by |
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166 <i>TIFFRGBAImageBegin</i> and then invoke them before or |
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167 after each display operation. For example, the |
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168 <i>tiffgt</i>(1) utility uses the following put method to |
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169 update the display as the raster is being filled:</p> |
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170 <!-- INDENTATION --> |
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171 <pre>static void |
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172 putContigAndDraw(TIFFRGBAImage* img, uint32* raster, |
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173 uint32 x, uint32 y, uint32 w, uint32 h, |
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174 int32 fromskew, int32 toskew, |
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175 unsigned char* cp) |
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176 { |
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177 (*putContig)(img, raster, x, y, w, h, fromskew, toskew, cp); |
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178 if (x+w == width) { |
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179 w = width; |
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180 if (img->orientation == ORIENTATION_TOPLEFT) |
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181 lrectwrite(0, y-(h-1), w-1, y, raster-x-(h-1)*w); |
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182 else |
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183 lrectwrite(0, y, w-1, y+h-1, raster); |
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184 } |
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185 } |
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186 </pre> |
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187 <!-- INDENTATION --> |
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188 <p>(the original routine provided by the library is saved in |
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189 the variable <i>putContig</i>.)</p> |
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190 </td> |
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191 </table> |
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192 <a name="SUPPORTING ADDITIONAL TIFF FORMATS"></a> |
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193 <h2>SUPPORTING ADDITIONAL TIFF FORMATS</h2> |
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194 <!-- INDENTATION --> |
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195 <table width="100%" border=0 rules="none" frame="void" |
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196 cols="2" cellspacing="0" cellpadding="0"> |
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197 <tr valign="top" align="left"> |
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198 <td width="8%"></td> |
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199 <td width="91%"> |
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200 <p>The <i>TIFFRGBAImage</i> routines support the most |
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201 commonly encountered flavors of <small>TIFF.</small> It is |
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202 possible to extend this support by overriding the |
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203 ‘‘<i>get method</i>’’ invoked by |
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204 <i>TIFFRGBAImageGet</i> to read <small>TIFF</small> image |
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205 data. Details of doing this are a bit involved, it is best |
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206 to make a copy of an existing get method and modify it to |
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207 suit the needs of an application.</p> |
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208 </td> |
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209 </table> |
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210 <a name="NOTES"></a> |
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211 <h2>NOTES</h2> |
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212 <!-- INDENTATION --> |
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213 <table width="100%" border=0 rules="none" frame="void" |
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214 cols="2" cellspacing="0" cellpadding="0"> |
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215 <tr valign="top" align="left"> |
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216 <td width="8%"></td> |
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217 <td width="91%"> |
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218 <p>Samples must be either 1, 2, 4, 8, or 16 bits. |
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219 Colorimetric samples/pixel must be either 1, 3, or 4 (i.e. |
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220 <i>SamplesPerPixel</i> minus <i>ExtraSamples</i>).</p> |
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221 <!-- INDENTATION --> |
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222 <p>Palette image colormaps that appear to be incorrectly |
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223 written as 8-bit values are automatically scaled to |
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224 16-bits.</p> |
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225 </td> |
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226 </table> |
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227 <a name="RETURN VALUES"></a> |
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228 <h2>RETURN VALUES</h2> |
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229 <!-- INDENTATION --> |
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230 <table width="100%" border=0 rules="none" frame="void" |
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231 cols="2" cellspacing="0" cellpadding="0"> |
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232 <tr valign="top" align="left"> |
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233 <td width="8%"></td> |
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234 <td width="91%"> |
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235 <p>All routines return 1 if the operation was successful. |
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236 Otherwise, 0 is returned if an error was encountered and |
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237 <i>stopOnError</i> is zero.</p> |
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238 </td> |
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239 </table> |
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240 <a name="DIAGNOSTICS"></a> |
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241 <h2>DIAGNOSTICS</h2> |
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242 <!-- INDENTATION --> |
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243 <table width="100%" border=0 rules="none" frame="void" |
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244 cols="2" cellspacing="0" cellpadding="0"> |
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245 <tr valign="top" align="left"> |
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246 <td width="8%"></td> |
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247 <td width="91%"> |
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248 <p>All error messages are directed to the |
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249 <i>TIFFError</i>(3TIFF) routine.</p> |
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250 <!-- INDENTATION --> |
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251 <p><b>Sorry, can not handle %d-bit pictures</b>. The image |
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252 had <i>BitsPerSample</i> other than 1, 2, 4, 8, or 16.</p> |
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253 <!-- INDENTATION --> |
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254 <p><b>Sorry, can not handle %d-channel images</b>. The image |
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255 had <i>SamplesPerPixel</i> other than 1, 3, or 4.</p> |
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256 <!-- INDENTATION --> |
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257 <p><b>Missing needed "PhotometricInterpretation" |
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258 tag</b>. The image did not have a tag that describes how to |
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259 display the data.</p> |
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260 <!-- INDENTATION --> |
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261 <p><b>No "PhotometricInterpretation" tag, assuming |
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262 RGB</b>. The image was missing a tag that describes how to |
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263 display it, but because it has 3 or 4 samples/pixel, it is |
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264 assumed to be <small>RGB.</small></p> |
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265 <!-- INDENTATION --> |
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266 <p><b>No "PhotometricInterpretation" tag, assuming |
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267 min-is-black</b>. The image was missing a tag that describes |
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268 how to display it, but because it has 1 sample/pixel, it is |
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269 assumed to be a grayscale or bilevel image.</p> |
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270 <!-- INDENTATION --> |
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271 <p><b>No space for photometric conversion table</b>. There |
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272 was insufficient memory for a table used to convert image |
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273 samples to 8-bit <small>RGB.</small></p> |
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274 <!-- INDENTATION --> |
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275 <p><b>Missing required "Colormap" tag</b>. A |
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276 Palette image did not have a required <i>Colormap</i> |
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277 tag.</p> |
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278 <!-- INDENTATION --> |
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279 <p><b>No space for tile buffer</b>. There was insufficient |
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280 memory to allocate an i/o buffer.</p> |
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281 <!-- INDENTATION --> |
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282 <p><b>No space for strip buffer</b>. There was insufficient |
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283 memory to allocate an i/o buffer.</p> |
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284 <!-- INDENTATION --> |
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285 <p><b>Can not handle format</b>. The image has a format |
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286 (combination of <i>BitsPerSample</i>, |
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287 <i>SamplesPerPixel</i>, and |
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288 <i>PhotometricInterpretation</i>) that can not be |
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289 handled.</p> |
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290 <!-- INDENTATION --> |
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291 <p><b>No space for B&W mapping table</b>. There was |
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292 insufficient memory to allocate a table used to map |
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293 grayscale data to <small>RGB.</small></p> |
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294 <!-- INDENTATION --> |
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295 <p><b>No space for Palette mapping table</b>. There was |
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296 insufficient memory to allocate a table used to map data to |
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297 8-bit <small>RGB.</small></p> |
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298 </td> |
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299 </table> |
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300 <a name="SEE ALSO"></a> |
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301 <h2>SEE ALSO</h2> |
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302 <!-- INDENTATION --> |
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303 <table width="100%" border=0 rules="none" frame="void" |
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304 cols="2" cellspacing="0" cellpadding="0"> |
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305 <tr valign="top" align="left"> |
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306 <td width="8%"></td> |
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307 <td width="91%"> |
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308 <p><b>TIFFOpen</b>(3TIFF), <b>TIFFReadRGBAImage</b>(3TIFF), |
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309 <b>TIFFReadRGBAImageOriented</b>(3TIFF), |
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310 <b>TIFFReadRGBAStrip</b>(3TIFF), |
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311 <b>TIFFReadRGBATile</b>(3TIFF), <b>libtiff</b>(3TIFF)</p> |
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312 <!-- INDENTATION --> |
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313 <p>Libtiff library home page: |
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314 <b>http://www.remotesensing.org/libtiff/</b></p> |
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315 </td> |
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316 </table> |
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317 <hr> |
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318 </body> |
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319 </html> |