Description:
Exporting a LibreOffice document (in my case, Writer) that is rich in images to a PDF generally works well.

However, there is a need to be able to produce small file sizes, as Adobe Acrobat does when requested.

Example 1:

One file creates a PDF of size 39.8 Mb using the lossless options on export-to-PDF. With 80% quality and image reduction to 300dpi, it creates a PDF of size 16.5 Mb. However, running the lossless version through Adobe Acrobat's option "Reduce File Size" creates a PDF of just 3.9 Mb, without visible loss of resolution (on-screen or printed).

Example 2:

A more extreme example is a 113.0 Mb PDF that Adobe Acrobat reduces to just 5.3 Mb, again without any visible loss of resolution.

Note that in both cases, the default settings were used in Adobe Acrobat.

Request:

I would like to see an option on the PDF export dialogue to achieve a similar reduction. A brief summary of how Adobe Acrobat does this is given here:

https://answers.acrobatusers.com/What-s-the-difference-between-Reduce-Size-PDF-and-Optimized-PDF-q107619.aspx

I quote (with some editing): "It resamples and compresses images; subset-embeds embedded fonts; compresses document structure; cleans up elements such as invalid bookmarks."

I suspect that the image-compression is the most important of these.

Thank you

Steps to Reproduce:
1. Create a Writer document that is rich in images, especially photographs. Include both JPG and PNG.

2. Export as PDF. Try to shrink the size without visible loss of resolution by playing with the options "JPEG compression" and "Reduce image resolution".

Actual Results:
The file size is generally within expected values, which is why this is a feature request and not a bug report.

Expected Results:
If a suitable option is provided, LibreOffice should shrink the file to its minimum size without visible loss in resolution, as the "Reduce File Size" feature of Adobe Acrobat achieves (as described above).

When this option is chosen, the options "Lossless", "JPEG Compression" and "Reduce image resolution" would be greyed out and ignored.


Reproducible: Always


User Profile Reset: Yes



Additional Info:
Version: 6.4.1.2
Build ID: 4d224e95b98b138af42a64d84056446d09082932
CPU threads: 4; OS: Linux 4.15; UI render: default; VCL: gtk3; 
Locale: en-GB (en_GB.UTF-8); UI-Language: en-GB
Calc: threaded

I have marked this as the latest release because that's what I currently use, but it predates this release by a long time.