Quote:
Originally Posted by willus
The method I posted does not re-encode the images in the PDF.
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OK, I just did a quick test. I extracted 10 pages from a scanned OCRed PDF using Acrobat. I then used your exact parameters, which are just the default ones you probably blindly copied from another post. Though I do that initially when I want to try something, I will then go and read the documentation and learn what other parameters I need to pay attention to. First off, the input file was 902kB, while the output file was 725kB. Second, I got an error:
Code:
GPL Ghostscript 9.15: Missing glyph CID=0, glyph=0067 in the font HiddenHorzOCR . The output PDF may fail with some viewers.
I then opened both files in Acrobat and maximized them and did a simple A-B comparison using the keyboard to switch rapidly back and forth multiple times. I looked at various pages and chose the better looking file without knowing which was which. Anything that was monochrome (black on white) was indistinguishable but grayscale images in the gs file definitely showed noticeable mosquito noise around lines and edges. So smaller file, missing glyph, noise, all indicators of lossiness. I didn't try it on text or vector graphics. It would no doubt be closer but probably not identical. In any case, using default settings for gs for every case is a mistake. You need to tweak the settings for each case. I've done countless hours of testing with many different settings and made notes on the results. Have you?
BTW, if I simply copy the PDF with cpdf to a new file, it is identical.