04-09-2021, 01:17 PM
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.
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.