Steps to replicate the issue (include links if applicable):
- Many Wikimedia Commons books were optimized to receive readable quality with as small size as possible. As the result their pages were often 750-900px wide.
- If you open a page of such a book, eg. https://commons.wikimedia.org/w/index.php?title=File:A_list_of_books_(with_references_to_periodicals)_on_Porto_Rico_(IA_cu31924021112887).pdf&page=19 you will see that the original page resolution (864 × 1,364 pixels in this case) is linked to much smaller thumbnail (500px wide in this case - 42% smaller), which is almost unreadable
- This policy makes the books useless in Wikimedia (eg. in Wikisource)
What happens?:
Available (linked) thumbnails are unreadable and so useless. 10-20% difference in size for optimized documents results in significant loss of quality.
What should have happened instead?:
Readable thumbnails with sizes as near to the actual page sizes need to be linked.
This probably can be achieved in one of 3 ways:
- generating the thumbnails for actual page size (may be different for each page)
- using more dense serie of widths (at least for multi-page documents)
- using upsized thumbnails (eg. 960px in the abovementioned case) for linking to
Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):
Other information (browser name/version, screenshots, etc.):