[ghusbands]

One cool related thing is that (I believe) modern graphics cards (even Intel) can store and use JPG blocks directly from GPU memory, so it's not necessarily beneficial in the long term to convert to RGBA in advance. Though I think no modern browser actually does this, especially given how power-cheap decoding jpeg (with SIMD) already is and how likely it is that gpu bugs would interfere.

[plekter]

I don't think they can use jpg directly, that would be a waste of transistors given that the graphics world use other compression formats like etc1, bc, astc and so on.

It is however perfectly possible to decode blocks of JPG on a GPU by using shader code.

[wiml]

I'm pretty sure that Safari (and probably most browsers) on MacOS renders JPEGs via CoreImage, and I have seen hints that CoreImage has various GPU-accelerated pathways, though I don't know whether those include DCT or JFIF on the GPU.