I have an input image: https://dl.dropboxusercontent.com/u/485 ... /Input.png
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I perform the following:
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Magick::Image img( "Input.png" );
img.write( "Output.png" );
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In Photoshop The input image is made up of a single colour, RGB( 139, 139, 139 ), the output image has been converted to grayscale (nothing wrong with that), however the colour is 45% i.e. RGB( 159, 159, 159 ). To me this feels like I bug; I understand (and appreciate) that ImageMagick is able to save out in optimal formats, however I'd expect the output image to match the input image (with a lossless format I'd expect a 100% match of the pixels).
So initially it definitely sounds like a bug, however, the images, when shown in a webpage (like this one) shows both images the same:
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Based on the webpage rendering of the images everything looks fine. My expectation at this stage is that Photoshop is doing something wrong (or perhaps looked at from a different viewpoint, Photoshop is treating the images in a way that Adobe deems as correct, but makes no sense to me)!
Any thoughts?