Is color blend mode broken?

[Artturi]

Hi! I've been quite much stuff with Affinity photo color blend mode and often I find out that it's not working in a way how it should work. Basically it's not only altering the color of the layer underneath, but also the value. Or is this a rendering problem? I also found out that if I add any FX to the layer, it fixes those artifacts. In case it means anything, I am running this on RTX 2060, windows 10. 

bug.afphoto

[walt.farrell]

16 minutes ago, Artturi said:

Basically it's not only altering the color of the layer underneath, but also the value.

I'm not sure what you mean by "value" in this context. The Blend modes are defined in terms of Hue, Saturation, and Luminance.

What it's supposed to do is this (from @dmstraker's Blend Mode Notes😞

Quote

Colour

Action: Creates a result colour with the luminance of the base colour and the hue and saturation of the blend colour.

Formula: Result = Hue(Blend) + Saturation(Blend) + Luminance(Base)

Effect: Preserves base layer luminosity. Colour comes from blend layer. Opposite of Luminosity. Stronger than Hue as it takes saturation from Blend layer rather than Base layer.

 

[Artturi]

6 minutes ago, walt.farrell said:

I'm not sure what you mean by "value" in this context. The Blend modes are defined in terms of Hue, Saturation, and Luminance.

What it's supposed to do is this (from @dmstraker's Blend Mode Notes😞

 

It's creating those weird light spots in the image, even when the color layer don't have anything else expect one color and therefore those shouldn't be happening. 

[walt.farrell]

5 minutes ago, Artturi said:

It's creating those weird light spots in the image,

The Luminance comes from the lower layer. The upper (blend) layer only contributes Hue and Saturation.

[Artturi]

7 minutes ago, walt.farrell said:

The Luminance comes from the lower layer. The upper (blend) layer only contributes Hue and Saturation.

Yep. So this is a bug? 

[walt.farrell]

Just now, Artturi said:

Yep. So this is a bug? 

No. It's the way that blend mode is defined to work.

[Artturi]

3 minutes ago, walt.farrell said:

No. It's the way that blend mode is defined to work.

But the color layer is changing the luminance even when it's not supposed to do so... See this video. Or at least something it is doing wrong, since it creates those spots. 

2021-08-22 17-25-44.mkv

[GaryLearnTech]

Hi @Artturi  I can't put my finger on what's causing those cyan artefacts/highlights, sorry – your file opens and displays fine on my Mac system.

Could this be one of those your-graphic-card-driver-needs-updated scenarios that sometimes seems to trouble Windows users?

What version of Affinity Photo are you using?

[Old Bruce]

49 minutes ago, Artturi said:

But the color layer is changing the luminance even when it's not supposed to do so... See this video. Or at least something it is doing wrong, since it creates those spots. 

I think you have just managed to find a particular (green) colour that gives that result.

[Dan C]

14 minutes ago, GaryLearnTech said:

Hi @Artturi  I can't put my finger on what's causing those cyan artefacts/highlights, sorry – your file opens and displays fine on my Mac system.

Could this be one of those your-graphic-card-driver-needs-updated scenarios that sometimes seems to trouble Windows users?

Similar to Garys findings, this file opens correctly for me on Windows -

I suspect that this is a rendering issue - please download the latest driver from Nvidia and perform a 'Clean Installation', by selecting 'Custom Install' when offered 2 options.

If this does not change things, please navigate to Edit > Preferences > Performance and untick Hardware Acceleration at the bottom of the dialog. Restart the app as prompted and then load your document once more.

Do either of these steps resolve this rendering issue for you please?

[walt.farrell]

19 minutes ago, Artturi said:

But the color layer is changing the luminance even when it's not supposed to do so...

If I choose the color from your blend (upper) layer, and pick a particular spot in your base (lower) layer that looked interesting to me, I get the following (values listed are sampled from the image, and the two small squares are the same color, but the one on the left uses Color blend mode):

I can see there that the blend layer with Color blend mode kept the H and S values of the blend layer. But you're right that it also affected the L value of the result, pulling L up from 72 on the base to 81.

I'm not sure why that happens, but I recall a somewhat recent discussion here, which unfortunately I cannot find again, which delved deeper into blend modes. One of the points raised there (if i remember correctly) was that we speak of the blend modes as being based on Hue, Saturation, and Luminance but they are really defined based on other aspects (such as Chroma and Luma, not Hue or Luminance). But even considering HSL, I think the calculation of L involves the L of both the blend and the base layers.

Color-Blend-Mode.afphoto

[Artturi]

2 hours ago, GaryLearnTech said:

Hi @Artturi  I can't put my finger on what's causing those cyan artefacts/highlights, sorry – your file opens and displays fine on my Mac system.

Could this be one of those your-graphic-card-driver-needs-updated scenarios that sometimes seems to trouble Windows users?

What version of Affinity Photo are you using?

I'm using 1.10. And my GeForce drivers seem to be up to date. Tho I don't have studio drivers, but game ready drivers. 
Never mind, there actually was a "optimize" button in the GeForce experience settings for affinity photo. After that click the problem disappeared at least mostly. Now it's doing only very slightly the same thing. 
 

[Artturi]

Here is my older experiment with the same problem, but I think that "optimize" thing probably fixed the problem at least mostly. 

A bug in Affinity Photo? - YouTube 

[NotMyFault]

Hi,

i assume a bug in retail (left). Renders OK on beta (right).

Windows 10

Maybe related to

https://forum.affinity.serif.com/index.php?/topic/147356-blend-mode-saturation-with-hue-060-issue/&tab=comments#comment-820973

 

 

[Wosven]

Damn, updating the drivers isn't always a panacea... I set "optimize apps" for all apps possible, and if the Affinity ones are faster, Menu entries disapear when the cursor is on them, so I can't click them.

Same problem for right-click menu that appear and disapear in a blink 😢

[walt.farrell]

40 minutes ago, Wosven said:

and if the Affinity ones are faster, Menu entries disapear when the cursor is on them, so I can't click them.

That sounds like Nahimic is active.

 

[Wosven]

9 minutes ago, walt.farrell said:

That sounds like Nahimic is active.

Thanks, but it's not it. But now I need to quit all the GPUtweak II and Asus utilities or I'm unable to click on menu options 

[walt.farrell]

1 hour ago, Wosven said:

Thanks, but it's not it. But now I need to quit all the GPUtweak II and Asus utilities or I'm unable to click on menu options 

Some if those may install Nahimic as a Windows Service, not as a normal application. If you haven't looked there, you should.

[R C-R]

18 minutes ago, walt.farrell said:

Dinner if those may install Nahimic as a Windows Service, not as a normal application. If you haven't looked there, you should.

"Dinner"?

[walt.farrell]

39 minutes ago, R C-R said:

"Dinner"?

Sigh. Common auto-correct problem for me on my phone for "Some". Thanks. Fixed. (I try to remember to look, but sometimes I miss one.)

[Wosven]

5 hours ago, walt.farrell said:

Some if those may install Nahimic as a Windows Service, not as a normal application. If you haven't looked there, you should.

Not as service either, I checked both. It seemsto be more complex than this exe.

I suspect, since only NVIDIA drivers were updated (and those folders modified), that it's a problem with the Nvidia Display Container  or the Nvidia GeForce Experience.exe and  Monitor and GPUTweak exe files.

Strangely, launching them now don't cause any problem... 

Next tests this evening.