braver

I just experienced a histogram that wouldn't update, using OpenGL, no metal-compute. Indeed saving the file seems to have un-stuck the histogram and now it updates again. So this does sound related.

This seems to be my experience. OpenGL works for me, so I don't really have a problem here. I guess the implementation using metal was deemed stable enough to make it the default, which it probably is for most users. It's the informatie feedback in this thread that can help move the implementation forward (the venting doesn't really add anything guys, please keep it constructive).

Some additional context. 90% of my work in Affinity Photo is retouching and editing high resolution scans of black and white negatives. So my primary tools are the inpainting brush, levels and curves, and the histogram. In previous versions metal was marked as “beta” and I have tried to enable the options. It has never been performant for me for the tools I need, so I never did anything more than dabble with the metal options. Now they’re presented as stable or even default options, but the performance is still unacceptable for some features. Not just slow, but orders of magnitude too slow.

I'd just like to chime in to say that for me, on a 2018 MacBook Pro 15", the histogram is erratic if metal is switched on. Sometimes it's pretty slow to update. 20+ seconds sounds about right. Also the histogram underlays in the levels and curves popups sometimes take a long time to show up. Often long enough I stop waiting for them. I'm not sure if they would after several minutes, I never waited that long. Also, I use the Marquee option a lot for the histogram and with metal compute on it's useless: chances are it will never update to reflect the marquee selection. Or at least, I'm not going to sit and wait for 5 minutes to check. When I switch off metal compute all of this is essentially instant, updates to the histogram take < 1sec in all cases, even on huge images. Since metal also slows down the inpainting brush, I keep it on OpenGL. I must say I'm confused about the effects of metal for the display setting, and metal compute. If I understand the marketing, things should be faster with metal, but all I see are very serious slow downs in essential features. I thought the histogram update problem went away with metal compute off, but I really need to switch back to OpenGL fully for it to be performant for me. By the way, I work almost exclusively on ~24MP 16bit Tiff files.

I make extensive use of the inpainting brush. It's excruciatingly slow when metal compute is turned on. I don't seem to experience a real slowdown otherwise, but it being unusable with metal compute on I haven't spent much time with 1.7 and metal compute. I never used the beta, but wasn't there an option to try out metal compute in 1.6? I seem to remember there was, and that it was unusable wrt. the inpainting brush. It's good without metal compute though. ¯\_(ツ)_/¯