Question: are the "original" image filenames "stored" (with the image data) in the pdf file? #71

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opened 2021-04-25 19:58:39 +00:00 by josch · 0 comments

josch commented

2021-04-25 19:58:39 +00:00

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By jaimet on 2020-04-13T14:14:02.981Z

Hi! Just a question: if I use img2pdf to create a pdf file from, say, "mySpecialFilename.jpg", is the filename "mySpecialFilename.jpg" stored somewhere in the pdf file? I am wondering whether I can use the resulting pdf file to record the filename, but when I try "doing the reverse" using pdfimages, all I get out is 000.jpg. Do you know whether the original filename is discarded during "conversion" to pdf, or is pdfimages discarding this information during "extraction"? Thank you!

By josch on 2020-04-13T15:19:17.291Z

Yes, the original filename is discarded. The pdf format does allow you to record where a file that was included in it came from. This is not surprising because other formats don't do that either. A image you edit with gimp also does not store from which file each of its parts come from -- there could even be no file at all. If you want to somehow retain the filename, then maybe pdf page labels are something useful for you because img2pdf put each image on its own page: http://gitlab.mister-muffin.de/josch/img2pdf/issues/57

By josch on 2020-08-04T07:02:49.037Z

Status changed to closed

*By jaimet on 2020-04-13T14:14:02.981Z* Hi! Just a question: if I use img2pdf to create a pdf file from, say, "mySpecialFilename.jpg", is the filename "mySpecialFilename.jpg" stored somewhere in the pdf file? I am wondering whether I can use the resulting pdf file to record the filename, but when I try "doing the reverse" using [pdfimages](https://cgit.freedesktop.org/poppler/poppler/tree/utils/pdfimages.cc), all I get out is `000.jpg`. Do you know whether the original filename is discarded during "conversion" to pdf, or is pdfimages discarding this information during "extraction"? Thank you! --- *By josch on 2020-04-13T15:19:17.291Z* --- Yes, the original filename is discarded. The pdf format does allow you to record where a file that was included in it came from. This is not surprising because other formats don't do that either. A image you edit with gimp also does not store from which file each of its parts come from -- there could even be no file at all. If you want to somehow retain the filename, then maybe pdf page labels are something useful for you because img2pdf put each image on its own page: http://gitlab.mister-muffin.de/josch/img2pdf/issues/57 --- *By josch on 2020-08-04T07:02:49.037Z* --- Status changed to closed