"Apply Image" with LAB wrong when Metal Enabled (1.7.0)

[IPv6]

There is a problem with "Apply Image" filter when metal is enabled and when not enabled. It produce different results. see screenshots.

Right result when metal is NOT enabled (screenshot 1-filter/1-opts), when metal is "on" - result too much white (screenshot 2-filter/2-opts).
In other cases it looks like like filter with Metal "on" try to make channel value above 1, clamping colors

[IPv6]

Happens with some other filters too //

[Chris B]

Hey IPv6,

Do you have the beta installed and if so, can you still reproduce this? I've been checking the filters as I go but this one seems to be behaving for me in the beta. I'd appreciate a second opinion.

[IPv6]

1 hour ago, Chris B said:

Hey IPv6,

Do you have the beta installed and if so, can you still reproduce this? I've been checking the filters as I go but this one seems to be behaving for me in the beta. I'd appreciate a second opinion.

Yes, the same problem exist in latest beta as well. Metal-powered execution of "Apply Image" filter in LAB mode is completely wrong // Looks like LAB values are offsetted, making everything "whitish" and causing clamping where it should not (i use this filter in macros for LAB transformations and difference is big)

[IPv6]

Curves and Channel mixer are ok, though, in beta... i was under impressions they suffer from same problem but in beta they are not.
So only apply image affected
 

[MEB]

Hi IPv6,
I've reproduced this here. Issue logged to be looked at.

[Chris B]

47 minutes ago, IPv6 said:

Curves and Channel mixer are ok, though, in beta... i was under impressions they suffer from same problem but in beta they are not.
So only apply image affected
 

Yeah I had another go and came back to tell you I've cracked it. Thanks @MEB

[hanshab]

selective color adjustment has this problem  in LAB where it changes a saturated blue to magenta without making any changes  ie happens as soon as you call up the selective color adjustment  first picture is before selecting selective color adjustment second is after selecting selective color adjustment without making any changes in the sliders.

[IPv6]

Still a problem in beta 1.7.2.147 (Regarding "Apply image" in LAB mode with Metal compute enabled) //

[MEB]

Hi IPv6, 
Yes, there's still issues here, sorry. Note that's actually the Metal output that's correct (not the opposite). The issue/log is still open for reviewing/fix.

[MEB]

On 6/15/2019 at 5:09 PM, hanshab said:

selective color adjustment has this problem  in LAB where it changes a saturated blue to magenta without making any changes  ie happens as soon as you call up the selective color adjustment  first picture is before selecting selective color adjustment second is after selecting selective color adjustment without making any changes in the sliders.

Hi hanshab,
Thanks for your report and sorry for the late reply. This issue should now be fixed in the latest Affinity Photo Customer Beta 1.7.2.147.

[IPv6]

4 hours ago, MEB said:

Hi IPv6, 
Yes, there's still issues here, sorry. Note that's actually the Metal output that's correct (not the opposite). The issue/log is still open for reviewing/fix.

"Metal output that's correct (not the opposite)" - so something changed behind LAB calculations? i see... Please, provide us (AP users, i mean) with exact information about how Affinity Photo treat A/B channels in filters, after all... I heavily use calculations over lab channels for some effects - and unusual non-documented mapping stuff (i suspect that channel value limits between Metal/Non metal was changed? or anything) does not help. As well as endless guessing for "right remapping mindfuck" to make some LAB-related filters just to work as expected //