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comparison libinterp/dldfcn/__magick_read__.cc @ 20373:a7770c66cb3d

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Saturated red channel on RGB image, makes imread() return logical (bug #41584) * libinterp/dldfcn/__magick_read__.cc (get_depth): this function tries to second guess GM when reporting the actual bitdepth of an image in the file (see comments for full discussion). We assumed we could check only red from RGB but if the channel was saturated, it would return depth of 1, so we really need to check all 3 channels. Unfortunately, 3 saturated channels may still lead to images incorrectly read as logical. * scripts/image/imread.m: add test for this bug.
author Carnë Draug <carandraug@octave.org>
date Fri, 10 Jul 2015 16:46:24 +0100
parents a9574e3c6e9e
children 5b8e4f668c53
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20372:8e056730f27c 20373:a7770c66cb3d
113 // Anyway, using depth() seems that only causes problems for binary 113 // Anyway, using depth() seems that only causes problems for binary
114 // images, and the problem with channelDepth() is not making set them 114 // images, and the problem with channelDepth() is not making set them
115 // all to 1. So we will guess that if all channels have depth of 1, 115 // all to 1. So we will guess that if all channels have depth of 1,
116 // then we must have a binary image. 116 // then we must have a binary image.
117 // Note that we can't use AllChannels it doesn't work for this. 117 // Note that we can't use AllChannels it doesn't work for this.
118 // Instead of checking all of the individual channels, we check one 118 // We also can't check only one from RGB, one from CMYK, and grayscale
119 // from RGB, CMYK, grayscale, and transparency. 119 // and transparency, we really need to check all of the channels (bug #41584).
120 static octave_idx_type 120 static octave_idx_type
121 get_depth (Magick::Image& img) 121 get_depth (Magick::Image& img)
122 { 122 {
123 octave_idx_type depth = img.depth (); 123 octave_idx_type depth = img.depth ();
124 if (depth == 8 124 if (depth == 8
125 && img.channelDepth (Magick::RedChannel) == 1 125 && img.channelDepth (Magick::RedChannel) == 1
126 && img.channelDepth (Magick::GreenChannel) == 1
127 && img.channelDepth (Magick::BlueChannel) == 1
126 && img.channelDepth (Magick::CyanChannel) == 1 128 && img.channelDepth (Magick::CyanChannel) == 1
129 && img.channelDepth (Magick::MagentaChannel) == 1
130 && img.channelDepth (Magick::YellowChannel) == 1
131 && img.channelDepth (Magick::BlackChannel) == 1
127 && img.channelDepth (Magick::OpacityChannel) == 1 132 && img.channelDepth (Magick::OpacityChannel) == 1
128 && img.channelDepth (Magick::GrayChannel) == 1) 133 && img.channelDepth (Magick::GrayChannel) == 1)
129 depth = 1; 134 depth = 1;
130 135
131 return depth; 136 return depth;