When trying to convert a group of JPEGs to PDF using DT3’s “Convert to PDF” option, the converted PDF files are up to 10x larger than the source JPEG files. What can I do to avoid such as significant increase in file size?
The source JPEGs are MacOS screenshots.
First of all, a JPEG is a compressed file format and simpler than PDF.
Secondly, what are your settings in DEVONthink’s Preferences > OCR?
First, what @BLUEFROG should be noted.
Reduce the Resolution to get the reduced file size you seek.
(when I save PDF’s of web page, I use 75 dpi. If I ever need higher, which is pretty much never, I can always go back to the web page and get a new one, if still there. For you, I recommend you keep the JPEG’s if you need resolution. That’s what the file format is designed for. Read about JPEG on the 'net. No need to keep trying to bend PDF’s to your will.)
AFAIK, PDF allows embedding of JPEGs as they are, i.e. compressed (same goes for TIFF)
and
https://www.bullzip.com/kb/pdf-image-quality-and-compression/
@Rudy: It might be worthwile, too, to rethink if you really want to save screenshots as JPEGs. If they contain dialogs etc., a lossless format like PNG might be a lot (a lot!) better, because it doesn’t introduce visual artefacts (which PNG invariably does). Also, PNGs compression is geared towards more “graphical” content (like typical screenshots, printed documents with rapid color changes), whereas JPEG has been developed to store photos, more generally images with slow and subtle color changes between pixels.
Yes, that is all true. However, compression is optional in a PDF and some algorithms are very aggressive; others much less so.
