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Comment by Tobani | Hacker News Reader

They're different beasts.

JPEGS are great for photographs, where lossy compression is acceptable.

PNGs can have transparency and lossless compression, so they're great for things like rasterized vector graphics, UI-element parts of a web page, etc.

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PNGs are also ideal for color accuracy since one of the things you lose quickly when converting to JPEG is the ability to have an exact RGB value flow from input to output, even at a high quality level. So if you want i.e. a banner graphic to seamlessly blend in with your site's background color, JPEG is worse for that.

Sorry, but that sounds more like a problem with your color management systems and workflows and not so much with JPEG itself.

JPEGs are intrinsically YCbCr not RGB, so I don't know how you would avoid some precision loss when you combine that colorspace conversion with things like the quality level and (potentially) subsampling.

Are they? I thought JPG could switch? I know jpegli uses XYB colorspace in JPGs.

JPEG can be YCbCr, RGB or even CMYK (usually from Photoshop or similar software). There can also be unusual subsample ratios for YCbCr, such as 4:2:1. I created some WASM Go bindings for jpegli, and I recall that such images cannot be represented in Go; therefore, for these images, I force RGBA output.

Also, XYB is an option; I use the adaptive quantisation option from jpegli (with progressive level 2) to get smaller files. I never bothered with XYB, as it looked complicated.

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