Quote:
Originally Posted by carmenchu
Today, making an epub (2) from collected html pages, I found that Sigil put all the webp images into the <misc> folder...
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As others have stated:
Anything outside of GIF, JPG, PNG, SVG... isn't going to be supported (if at all):
https://www.w3.org/publishing/epub32...-cmt-supported
... and
especially in the case of EPUB2 readers.
Quote:
Originally Posted by carmenchu
As webp offers almost double quality for half the weight than jpg, I am thinking to change the covers of my personal books to that format, besides using them inside.
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Conversion from a lossy format to another lossy format is rarely a good idea. You're going to introduce even more artifacting.
Best to only convert to lossy WEBP if you're going from a lossless source (like PNG).
Quote:
Originally Posted by DNSB
I do wonder about the claim of double quality for 50% of the file size. In our testing, we found ~25% better compression for WebP lossy compared to JPEG.
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JPG is also notorious for blocking, ringing, and banding, where WEBP has much less of those types of artifacts (these newer algorithms tend to get smoother/fuzzier instead).
These two are some of the better image comparison sites I've run across:
https://wyohknott.github.io/image-formats-comparison/
https://people.xiph.org/~tdaede/av1stilldemo/
WEBP is definitely the most well-supported post-JPG format, and it's great that so many browsers now have support for it. (Ebooks, not so much!)
Although if pure compression is your goal, there's newer image formats beyond WEBP (although browser support is non-existent).
- HEIC = based on HEVC (next generation MPEG format)
- This is the format latest iPhones save photos in.
- AVIF = based on AV1 (next generation video encoding).
- AV1 is the format a huge portion of the video industry is getting behind, since it's open and royalty free.
- The tools aren't really there yet to easily create these types of images.
Complete Compression Side Note: I recently noticed a checkbox in GIMP's Save As JPG called
arithmetic coding. Turns out this is/was a way to implement instant 10% savings on all JPGs, but it was mired in patents. By the time the patents expired (only relatively recently), every single tool/browser/everything has since moved on, and has nearly 0 support for such JPGs.
Quote:
Originally Posted by DNSB
For work, we tried WebP on a couple of webservers and it was a total PITA. We still needed to keep the JPEG, PNG, etc. images for web browsers which did not support WebP and the ~25% compression increase still left us chewing up server hard drives like we got them for free.
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Yep, sacrificing hard drive space for (potentially) very large bandwidth savings.
Seems like it would be the yet-another-format implemented at the server-level, then serve whichever format the device supports best.
And like I mentioned above, the types of artifacting in these newer formats is better than JPG's blockiness.