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pdf export hardwired at 100 dpi

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pdf export hardwired at 100 dpi jhy001 12 Aug 14:55
  pdf export hardwired at 100 dpi rich404 15 Aug 08:31
   pdf export hardwired at 100 dpi jhy001 15 Aug 17:09
2022-08-12 14:55:48 UTC (4 months ago)
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pdf export hardwired at 100 dpi

A friend of mine has newspaper jpg scans and an OCR package that only reads pdf. He uses Gimp to save from jpg (300 dpi) to pdf, but the fixed 100 dpi doesn't OCR very well.

For the life of me I can't find, nor understand why it isn't available, to set the pdf export dpi to 300, or at least use the SAME dpi as in the jpg original.

I've looked for other jpg to pdf programs, but the useful ones seem to all be cost or require advanced Unix skills to install and use.

Can the dpi be reset for pdf to 300 in Gimp somehow?

TIA.

2022-08-15 08:31:45 UTC (4 months ago)
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pdf export hardwired at 100 dpi

A friend of mine has newspaper jpg scans and an OCR package that only reads pdf. He uses Gimp to save from jpg (300 dpi) to pdf, but the fixed 100 dpi doesn't OCR very well.

For the life of me I can't find, nor understand why it isn't available, to set the pdf export dpi to 300, or at least use the SAME dpi as in the jpg original.

I've looked for other jpg to pdf programs, but the useful ones seem to all be cost or require advanced Unix skills to install and use.

Can the dpi be reset for pdf to 300 in Gimp somehow?

TIA.

Not hardwired.

Very often the confusion is the user working in real-world units while Gimp is a raster editor and works in pixels. If you create a canvas with the correct size in pixels and the resolution set, then you export the appropriate PDF. All Gimp does is embed the bitmap image in a PDF wrapper. You can check from file size.

Two examples, the same image:

6"x 4" @100 ppi = 600x400 pix and exported as a PDF = 350 kb 6"x 4" @300 ppi = 1800x1200 pix and exported as a PDF = 2200 kb
Either opened in a pdf viewer gives the size as 6"x4" but for the 100 ppi version, zoom in and quality can suffer.
For new Gimp users the confusion is when opening a PDF.
The default resolution is set to 100 ppi. Gimp will start with this value, a PDF does not set the ppi. A PDF often has vector elements and text which is rendered by Gimp to a bitmap. It is up to the user to set a different value depending on desired quality. See the screenshot of Gimp import dialogue and PDF properties.
You want to use jpg's. That will get you a smaller PDF
For a 300 ppi jpeg ImageMagick command line wraps the image as a PDF magick 6x4-300.jpg -density 300 new.pdf and that gets the 300ppi / 2200 kb Gimp PDF down to 290 kb file size
When it comes to PDF creation, because of the low internal compression, Gimp does makes large PDF's. Often better to use an application like Scribus or even LibreOffice especially when there is text. No difficulty installing either if using linux.

This forum is largely abandoned to spammers. There are other moderated Gimp forums.

2022-08-15 17:09:37 UTC (4 months ago)
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pdf export hardwired at 100 dpi

Not hardwired.

Got it! Thank you for taking the time to explain all this! It makes sense, and is much appreciated.