Is it possible to add ICC profile to PDF document without images recompression?

[shijan]

Small problem that i attempt to fix. I have one PDF document that seems don't have embedded ICC profile, so in any macOS PDF viewer all images in this document look oversaturated on wide gamut display. Formally it is a bug in macOS, because it should use sRGB instead of empty profile, but it don't...
So i was thinking, maybe it is somehow possible to use PhotoLine to add ICC profile to PDF document without images recompression? That PDF contains only images, no text or vector shape.

[shijan]

So i repacked PDF with sRGB ICC profile to PDF with Zip compression and file size remains near the same as original (increased less than 1 MB, probably due additional generated thumbnail).
By the way, i guess it might be useful to show somewhere in Browser Info which sort of image compression used in PDF.

[Hoogo]

There's some logic for JPeg layers: A copy of the original compressed Jpg data is kept, you can see it in the layer attributes.
If the bitmap is changed, then the copy is discarded.
If the bitmap is untouched, the copy is saved IF it is smaller than a freshly compressed version.

So saving a PDF with Jpg hQ should work without new compression. PDF24 has a compression tool included, it often saves a little more.

[shijan]

Nice. I didn't know how that Pic Data field in Layer Attributes works. So i made some tests, saved PDF with compression Jpeg HQ, as Uncompressed and as Zip.
Exported PDF file sizes where different and export time was different, but when i open those saved versions in PhotoLine, JPEG image layer size was exactly same size. So PhotoLine works really smart and when possible don't changes source JPEG data. PDF saved with compression Jpeg Low changed layer size, exactly as you told.

I guess it is logical to request (if possible) to show somewhere in Browser Prop tab info about text and image compression type used in PDF.

Screen Shot 2025-08-17 at 3.28.22 PM.jpg

[Martin Huber]

I guess it is logical to request (if possible) to show somewhere in Browser Prop tab info about text and image compression type used in PDF.

There is no uniform compression type in PDF. Each data stream can and often is compressed differently.