Bug report: Blend mode (exclusion) not rendered correctly
I have a PDF file containing some text that should be color blended with the background using the blend mode "exclusion". However, the color of the text is displayed incorrectly in Adobe Acrobat Reader. At first, I thought that this is a problem with the program that created the PDF file and that the PDF file is flawed, but I have opened the file in several different PDF viewers and/or editors, including Wondershare PDFelement, Icecream PDF Editor, PDFgear, Okular and Sumatra PDF, as well as in various web browsers such as Firefox, Google Chrome and Microsoft Edge, and they all display the file contents as they look like in the program with which I created them. Even the iPhone version of Adobe Acrobat Reader displays the file as intended, so I very much assume that this is a problem of Acrobat Reader for Windows.
I have attached a screenshot showing how the file is rendered by Adobe Acrobat Reader and another one showing how it is rendered by Okular (and all the other programs I mentioned), in addition to the PDF file itself. My operating system is Windows 10 Home, and the version of Acrobat Reader I have installed is 2025.001.20630, 64-bit, which seems to be the latest version.
Maximilian Schamschula
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Maximilian Schamschula
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OK, upon inspecting this problem further, it turns out that it only seems to occur below a certain zoom level. When zooming in very closely, for instance to 800 %, the text appears to be displayed correctly.
Another thing I noticed is that, at lower zoom levels (even at 100 %), the weight of the glyphs is much too high, or in other words, the glyphs are too thick. While this problem also occurs when exporting the PDF without a blending mode for the text, it might still be related to the erroneous color rendering, because the more the weight of the glyphs normalizes when zooming in, the more the color of the text approaches the expected color.