Hi, we’re in the process of converting our PDF creation from using Apache FOP to Apache PDFBox.
To verify, if the output is nearly identical we use Ghostscript to convert the PDF to png and then use ImageMagick to compare both png files at the pixel level. In general this works excellent and the expectation is that we generate the same png output when everything is using exactly the same settings. However, we do notice some slight differences in the font output between FOP and PDFBox which I don’t have an explanation for. It looks like there is some kind of anti aliasing going on in the generated PDF file. These differences are displayed as a red outline but for some glyphs there are only partial differences. Please see the attached link with an example image. We output the word “Auftragsdetails” with the exact same font and output position and still see these weird partial differences at the outer edges of individual glyphs (Please note that the font is rendered regulary and in black color in both cases. The difference is only at the outer edge of the glyphs which ImageMagick shows in red). https://ibb.co/4S84j2c Bildschirmfoto-2024-07-22-um-10-46-31 hosted at ImgBB ibb.co I was under the impression that PDF stores the plain text, the font and possibly transformation information. But the image looks like there are differences in individual glyphs. They are slightly bigger in either FOP or PDFBox but not all of them which is weird. Does anyone have any hints or an explanation of what this could be? I’m puzzled. Thank you very much for your help and PDFBox in general! Best regards Jens PS: I would understand if the outlines are all to the left or the right or top or bottom since this would mean the text rendering position is slightly off but here it’s kinda all over the place.
