Color Picker Picks incorrect CMYK Values from FX on Layers

[josbin]

Heyhey, 

just stumbled upon a problem I dont really understand. Before filing a bug report, I wanted to ask if I am maybe doing something wrong. 

The problem is that the color picker doesnt pick the color i see in the document. I could recreate a similar problem as seen in Video in the affinity file, though less pronounced. I think it relates to the blending modes in the FX on the layer. 
Is this expected behaviour or a bug? And also why would it be stronger in the "karte" file? Any inspection on the problem would greatly be appreciated. Also this is a behaviour that can cause a lot of headache as it is hard to notice in some cases. So if it is a bug I would like to report it.

Here are the associated files:

1. Video Showing the problem.

2. File from the Video: "Karte V2 CMYK.psd"
This is a Photoshop-file, that got imported to AF Photo

3. Screenshot: FX layer settings of the trouble causing layer in the "Karte V2 CMYK.psd"

4. AF Photo File with a similar problem, though less pronounced. If you zoom in you can tell, that the colors dont match. The color got picked from the Shadow of the FX Layer. "CMYK COlor Picker not working correctly"


Hope this is all clear otherwise I am happy to provide further details!

Best

Karte V2 CMYK.psd CMYK Color Picker not working correctly.afphoto

[NathanC]

Hi @josbin,

Just focusing on your sample .afphoto file, it looks like the opacity of the outer shadow is set to 46%, If I set your document to have a transparent background to make the brush transparency easier to see and then sample from the outer shadow i'm given the CMYK values 13,68,67,24. This matches the CMYK values of the Outer Shadow FX adjustment exactly.

If I create a new pixel layer and brush onto the canvas with the sampled colour it will look different to the outer shadow as the opacity doesn't match, but If I adjust the opacity to 46% in the colour panel to match the outer shadow and then brush again, the colour on the canvas is the same as the outer shadow colour.

Since the sampled colours in this example match the original FX shadow colour correctly, could this be the case of an opacity mismatch? I did open your PSD file to compare, but it doesn't appear that the outer shadow FX layer is present on layer 6/layer 6 copy for me.

[josbin]

Hmm, good point. When i use 100% opacity on the shadow color picking works as excpected. But I tried to recreate it by matching opacity, and it still doesnt work as i would expect. In this sceenshot i matched the opacity to the FX opacity and the colors are still slightly off. For testing purposes you can find the layer from the psd in the example files under "Example 2".
In your example its hard to tell if they have the same color by eye as the checkered Background is a bit disturbing. 

So it seems to be related to opacity... 

[lepr]

4 minutes ago, josbin said:

So it seems to be related to opacity... 

In a CMYK document, semi-opaque colours are not correctly blended with the white 'canvas' in the document view. Use an actual white filled object (a Fill Layer or vector Rectangle for example) as the background instead of relying on the 'canvas'.

[NathanC]

Thanks for confirming @lepr I've just found the relevant bug report, i've now bumped the existing issue with your report @josbin .🙂

[josbin]

@lepr Thanks for confirming! Will do what you suggested for now then!

@NathanC Thanks for doing that!