02-26-2021, 09:48 AM
(This post was last modified: 02-26-2021, 10:57 AM by rich2005.
Edit Reason: typo
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Quote: Some make uncompressed PDFs but they make big files (Same 4 JPEGS is 97 MB in one of them), and no smoothing like with GIMP's.
I know you say you are not opening a PDF in Gimp but be careful what you are comparing. Gimp can re-render and introduce antialiasing (smoothing).
There is always a trade off between quality and file size. Exporting from Gimp then the factors are pixels-per-inch (ppi) and colour mode RGB or Greyscale (gs).
A typical A4 two page pdf from gimp @ 300 ppi RGB = 10 MB gs = 3.8 MB
and for the same @ 200 ppi RGB = 3.7 MB gs = 2 MB
A considerable saving in size by going greyscale and reducing ppi.
Quote:...I haven't found any that just put the JPEGs into the PDF wrapper without messing with the quality at all. Found one that makes minimal difference though.
A different situation when using ImageMagick (IM) where the files are added to the PDF wrapper
For a jpeg the quality setting is not linear, you can get a sizeable reduction in file size by going down from 90 to 80 and visually see very little difference.
For that 300 ppi RGB one page file size quality 90 = 1 MB and quality 80 = 0.74 MB and for gs 90 = 0.7 MB / 80 = 0.47 MB
For IM, that 2 page PDF could differ from a 300 ppi RGB = 1.8 MB down to a 200 ppi gs = 0.76 MB
At the end of the day, to a certain extent all in the eye of the beholder.
edit: just as a comparison, the extremes in a PDF viewer both 100% view size
Both readable, all depends on the content and what is considered acceptable.