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Transcoding images to a specified output format #101
Description
I'm thinking about a new feature for this plugin, that would allow transcoding source images into a specified output format. This would allow one to drop any image format into /content and transcode them to a particular format in the output. Say for example you have a mix of png, gif and jpg files in your source, the plugin would transcode them all to - for example - webp.
This would allow one to keep high-resolution, good quality images in the repository while still serving web-optimized images in the output.
The list of formats to transcode into, could be specified like this:
IMAGE_PROCESS = {
"artclimg": {
"type": "responsive-image",
--> "output-format": ["webp", "original"], # defaults to original when omitted to keep backwards compatibility; when present, srcset serves webp first, then original
"sizes": (
"(min-width: 1200px) 800px, " # Desktop: max 800px
"(min-width: 992px) 650px, " # Small Desktop: max 650px
"(min-width: 768px) 718px, " # Tablet: max 718px
"100vw" # Mobile: full width
),
"srcset": [
# scale_in will preserve ratio and resize to fit within the specified dimensions
("480w", ["scale_in 480 360 True"]),
("720w", ["scale_in 720 540 True"]),
("800w", ["scale_in 800 600 True"]),
("1000w", ["scale_in 1000 750 True"]),
("1200w", ["scale_in 1200 900 True"]),
],
"default": "800w",
},
}Instead of starting with a list, a first implementation could specify a single format to transcode into, e.g. "output-format": "webp".
Before I dig into this I want to check in with the maintainers. Would such a feature be a welcome addition? Any pitfalls to watch out for in the implementation? General thoughts?
Activity
patrickfournier commentedon Apr 3, 2026
That would be a nice addition. However I do not see how "output-format" as a list value would work. If we want to specify different file formats in a
srcset, I think we should specify the format along the transform operations.cargocultprogramming commentedon Jun 25, 2026
Issue is resolved. Feature implemented in #102