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sharpen up a pdf ?
#3
(04-09-2021, 01:17 PM)rich2005 Wrote: Trying to find something with a GUI and multi-layer provision.

Assuming that the single page PDF is representative of the whole 35 pages. It is an image wrapped up in a PDF, extracting the image (linux pdfimages) it comes out at about 2400 x 1600 pix A reasonable size but otherwise not great quality.

One way: 

1. Import the 35 pages setting the ppi to 300
2. Crop the page down, might save a bit of file size. Make sure 'Delete cropped pixels is ON



This using the Gimp g'mic plugin which can adjust all the layers. Get from http://www.gmic.eu

3. In the repair section "Repair Scanned Documents" to clean up the background a little. Set Smoothness = 1 / white level to 100 / black level to 0  Input set to All and Output in place or new image.  Apply that.
4. Another gmic filter in the Details section, Sharpen(deblur)  Just use the default settings and Input = All Output inplace (or new image)



Export that to a PDF. Warning Gimp makes big PDF's It is the way the image data is compressed. Nothing you can do about it.
This a comparison in a PDF viewer between the original and the Gimp PDF.

I've found that using the Erode filter to widen the lines improves the image a lot. Is there a GMIC equivalent?
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Messages In This Thread
sharpen up a pdf ? - by abrogard - 04-09-2021, 10:02 AM
RE: sharpen up a pdf ? - by rich2005 - 04-09-2021, 01:17 PM
RE: sharpen up a pdf ? - by Ofnuts - 04-09-2021, 04:41 PM
RE: sharpen up a pdf ? - by rich2005 - 04-09-2021, 04:53 PM
RE: sharpen up a pdf ? - by Ofnuts - 04-09-2021, 09:24 PM
RE: sharpen up a pdf ? - by Ofnuts - 04-10-2021, 07:20 AM
RE: sharpen up a pdf ? - by abrogard - 04-09-2021, 10:48 PM
RE: sharpen up a pdf ? - by rich2005 - 04-10-2021, 01:05 PM
RE: sharpen up a pdf ? - by Ofnuts - 04-10-2021, 07:36 PM

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