I switched to WebP about a year and a half ago. I’d been watching for a long time and it had finally reached the point where support was universal enough that I could not publish a JPEG.
WebP has the big advantage that the quality setting is meaningful, you can set it at a certain level and then encode thousands of images and know the quality is about the same. This is by no means true about JPEG, if you are trying to balance quality and size you find you have to manually set the compression level on each image. Years back I was concerned about the size of a large JPEG collection and recompressed them which was a big mistake because many of the images were compressed too hard.
In 2023 I think you can just use WebP and it will work well, my experience looking at images is that AVIF does better for moderate to low quality images but for high quality images it doesn’t really beat WebP.
> Years back I was concerned about the size of a large JPEG collection and recompressed them which was a big mistake because many of the images were compressed too hard.
Distortion metrics[0] such as MS-SSIM, MS-SSIM*, SIMM, MSE, and PSNR can be used to define a cut-off or threshold for deciding the point at which the image is "compressed enough" by using one or more of those algorithms and predefining the amount of acceptable/tolerable distortion or quality loss. Each of those algorithms has some trade-offs in terms of accuracy and processing time, but it can definitely work for a large set if you find the right settings for your use-case. It is certainly more productive than manually settings the Q-level per image.
Actually this isn't accurate, Kraken.io doesn't use any SSIM-related algorithms, it just blindly applies some standard compression regardless of the image's content.
You can use jpegli for better jpeg compression heuristics. It uses custom heuristics that were originally used in JPEG XL, then copied over and further optimized using nelder-mead to minimize distortion metrics (butteraugli and simulacra 2)
There is plenty of wrong or misleading information here:
- What is the cross supposed to mean for PNG compression of photographic images? PNG can compress photographic images just fine and for some applications (where you want lossless) it used to be a good choice.
- PNG has animation support, even if everyone except Firefox tried to
- While WEBP and AVIF support lossless compression and animation, those features are not available in all browser versions that support static lossy webp/avif images.
a) This is a property of the encoder, not of the image format.
and
b) Like any other video codec-based format, webp overcompresses dark areas in images so no, you can't rely on consistent quality across collections of arbitrary images.
WebP has the big advantage that the quality setting is meaningful, you can set it at a certain level and then encode thousands of images and know the quality is about the same. This is by no means true about JPEG, if you are trying to balance quality and size you find you have to manually set the compression level on each image. Years back I was concerned about the size of a large JPEG collection and recompressed them which was a big mistake because many of the images were compressed too hard.
In 2023 I think you can just use WebP and it will work well, my experience looking at images is that AVIF does better for moderate to low quality images but for high quality images it doesn’t really beat WebP.