Consider next gen image formats?

[Mousketeer]

I speak from great ignorance, but wouldn't it be interesting to support something more modern than jpeg - after all a 1992 format?

Newer formats offer far better compression ratios (meaning smaller and faster galleries at better quality) higher colour depth and space and a lossless option (not sure if that's a valid point in Sigal's context, but still).
Drawbacks include massively increased encoding time and slightly more complicated system requirements.

• WebP seems universally supported and a safe stepping stone.
• From the contenders for The Next Big Standard my pick is AVIF.
  • From the encoding side there is a Pillow plugin pending official merger.
  • Client side the latest chrome and firefox support it natively. There is avif.js that transparently (as in: clientside javascript decodes the image and paints it on the screen) brings support to 95% of the browser market. The fallback/upgrade mechanism for the current jpegs is elegant.

I'm afraid I can only "help" and not "do", but I thought to get something rolling with this issue.

[saimn]

Not sure about AVIF, which are the pros etc., but at least for webp, yes it would be great to support it. I think you can already try by adding the webp extension to img_extensions :

sigal/sigal/templates/sigal.conf.py

Lines 49 to 60 in 7ba5f7b

	# Output format of images (default: None, i.e. use input format)
	# img_format = "JPEG"
	# Show a map of the images where possible?
	# This option only has an effect on the galleria theme for the while.
	# The leaflet_provider setting allow to customize the tile provider (see
	# https://github.com/leaflet-extras/leaflet-providers#providers)
	# show_map = False
	# leaflet_provider = 'OpenStreetMap.Mapnik'
	# File extensions that should be treated as images
	# img_extensions = ['.jpg', '.jpeg', '.png', '.gif']

If you want to help with things other than code, a few more things would be useful:

• provide 1 or 2 test images in webp format, compatible with sigal's license
• find since which version of Pillow webp is supported (I guess it's not recent but a check can be useful)

Also it seems that support in Safari is very recent (macOS 11).

[Mousketeer]

Adding webp to img_extensions causes images to be generated flawlessly - Wonderful! There just isn't any fallback.

I've made a super bland nonsense image and it's herewith in the public domain: one and two (also in a gallery of course)

Different qualities yield very different file sizes (all available in the gallery above). But as mentioned file size isn't the only advantage.

Level	First image	Second image
lossy5	524K	124K
lossy8	600K	136K
lossy10	648K	144K
lossy60	1.9M	316K
lossy70	2.3M	364K
lossy75	2.5M	392K
lossy80	3.2M	504K
lossy85	4.4M	668K
lossy90	5.7M	1.1M
lossy95	30M	19M
lossless	30M	19M

[Mousketeer]

Based on the Changes file in the Pillow repository, the first mention of webp is in 2.1.0 (2013-07-02) with metadata support in 2.2.0, and I see no bugs beyond 5.1.0.
As far as I can see the current Sigal requirement for Pillow7 doesn't need to change to support webp.

[saimn]

Excellent, thanks !

[saimn]

webp is done with #433, thanks @Mousketeer for the test images. Maybe we can reconsider AVIF in the future when it is more widely supported ?

[DuendeInexistente]

Webp isn't quite there yet, it's an invalid setting for img_format .

Bit of an addenum but it's important for the format, would be good to also get a setting to make webp lossless if it's picked for that.

And something else besides that: webp supports animation too. I don't know what proccesor's used by this, but if it supports webp animation it'd be a mayor quality boost, even set to lossless webp makes way smaller files.

[saimn]

Good point 👍

[romain-dartigues]

Shall enabling the WebP make uses of the HTML5 <picture> element (with JPEG fallback) to get the best support?

[saimn]

I think WebP is also supported by <img> ? <picture> would be interesting if sigal could generate multiple sizes / formats but that's not the case currently.

[reagle]

Hi, I'm wondering if there's any news on avif support?