PDF export file size

[pburki]

Hello,

I have a problem with exporting an Affinity Publisher file into a PDF: the size of the resulting PDF is oversized. If I export 1 page of my book, consisting of 2 photos, using the PDF for print preset:

I get a PDF file of 38MB. If I export the same page as a jpeg at 300 dpi, I get a 9.2MB file. When I compare the 2 docs, it seems that the quality of the image in the PDF document is greater than the resolution of the JPEG. Any idea of what I am doing wrong ? My full book of 144 pages must be below 1GB (it is about right if I export all pages as JPEG, but I get a file of 36 GB when exported as PDF).

Thanks

Philippe

[lacerto]

Check that you do not have 16-bit source images, at least v1 could not convert them to 8-bit when exporting to PDF.

EDIT: Just tested with version2 (Windows), source images 16-bit and 8-bit PNGs with the default PDF (press-ready) export settings:

[pburki]

Thanks. Yes, the source file are 16-bit images. Does the fact that the source images are TIFF also is a problem?

[lacerto]

14 minutes ago, pburki said:

Does the fact that the source images are TIFF also is a problem?

I do not think so. If you allow JPG compression the export format of PNG will at least be changed to JPG (as PNG cannot be CMYK). But as shown, when Affinity converts those PNGs to JPGs, it retains the bit-depth, and its compression rate is very poor with 16-bit images (Photo would save the same images as 16-bit JPGs using much better compression).

EDIT: I just checked this with TIFF sources: the exported files are the same size, whether the sources are PNG or TIFF.