News for hackers. Stuff that matters.

A comment on John Carmack on JPEG. Parent comment

Re:John Carmack on JPEG by colonwqbang on Friday June 04, 2021 @07:03PM (#27400081)
In what way is RGB easier to manipulate? I get that it's the format we have to send to the monitor. Also, current tools may be geared more towards it. But on the face of it, I don't see why it is simpler. Do you have any good examples?

I can think of several image processing tasks which are more straightforward in a luma/chroma format. Maybe it's because I'm more used to working with the data in that form?

[ Parent | on HN ]
Re:John Carmack on JPEG by sbierwagen on Friday June 04, 2021 @07:11PM (#27400153)
>In what way is RGB easier to manipulate?

Probably because it's the native input format for every display technology in existence? If you're going to twiddle an image, you might want to do it in the format that it's displayed in.

[ Parent | on HN ]
Re:John Carmack on JPEG by pubby on Friday June 04, 2021 @08:14PM (#27400657)
Mostly the issue is the layout, not the color space. YUV420 is awkward to handle because it's "420", not because it's YUV. There wouldn't be too many issues if everything ran on the 1-byte-per-pixel-component YUV444, besides converting to/from RGB for certain processing steps.
[ Parent | on HN ]
Re:John Carmack on JPEG by colonwqbang on Saturday June 05, 2021 @06:51AM (#27403881)
It's quite common to upsample to 444 for processing, but using 420 for storage.
[ Parent | on HN ]