(Publisher) White background affect colors?!

[fpell]

This is driving me crazy, and I'm in a rush to deliver...

 

First one is a partially transparent background (rasterized otherwise I have a ton of additional problems when converting to PDF). The background layer is the first from the bottom, so nothing below it.

 

 

 

If I add a white rectangle behind, this happens. WTF

The green become significantly darker and less saturated. How's that?

 

[thomaso]

In Particular if you experience an apparently paradox result (white darkens…) it is useful or even required to show to the forum more than just brighter vs. darker colours. Currently it is unclear what object types you demonstrate with the uploaded PNG files (e.g. screenshots or exports, vector or pixel, et al. ?) nor how the document is setup in detail (e.g. with masks, adjustment layers, layer effects, rgb or cmyk, et al.).

Could you please upload a screenshot of your entire screen (incl. bars and panels) with the object in question selected and unfolded layers in the Layers Panel? And/or upload the related/affected objects (if they are placed resources) or, ideally, upload a sample document that includes the relevant layers and shows the issue?

[fpell]

Your extremely right, I should've added way more information. I'm working on Windows 11 with Affinity 2.5.5

 

This is what happens with screenshots grabbed with the Windows snipping tools. Rectangle layer (#ffffff, full page size) off:

 

 

And when I turn it on:

 

And this is the comparison:

 

 

Attaching also a reduce .afpub file that shows the problem, at least on my pc

test doc.afpub

[carl123]

If you go to File > Document Setup > Colour

and activate Transparent Background

You will see that the sfondo Layer is partially transparent

Noticeable when the white rectangle is switched off

[fpell]

8 minutes ago, carl123 said:

If you go to File > Document Setup > Colour

and activate Transparent Background

You will see that the sfondo Layer is partially transparent

Noticeable when the white rectangle is switched off

Yes I know that, but what I can't understand is how this would affect the colors, and how a transparent background would be handled when saving as PDF.

Isn't the sheet/artboard full white as well? At least that's how it's shown

 

I got that background by rasterizing and merging a few semi-transparent gradients, and I wanted to merge this onto a white background to finally have a matte background layer; but I then discovered that, once I place a white layer behind, color would get altered - and I really can't get why

[thomaso]

Thank you for more details! – Short answer: Flatten the affected layer, avoid its colour transparency and use reduced layer opacity instead (or maybe a separate mask layer).

I can't open your V2 but, assuming all involved layers have 100% opacity and blend mode normal, your Layers panel screenshots remind me to a known issue with colour transparency in Affinity. Below I reproduce the effect with reduced colour opacity, first in CMYK then in RGB document colour space. In RGB the problem seems to be smaller. And with layer transparency instead of colour transparency it seems to be even smaller, in CMYK, too (not demonstrated in the video).

The linked thread tries in ca. 90 posts to shed more light on this. Honestly I don't understand what Affinity actually does, especially since this thread considered gamma and grouping additionally to transparency and colour space and may run into various Affinity issues on its way.

[fpell]

16 hours ago, thomaso said:

Thank you for more details! – Short answer: Flatten the affected layer, avoid its colour transparency and use reduced layer opacity instead (or maybe a separate mask layer).

I can't open your V2 but, assuming all involved layers have 100% opacity and blend mode normal, your Layers panel screenshots remind me to a known issue with colour transparency in Affinity. Below I reproduce the effect with reduced colour opacity, first in CMYK then in RGB document colour space. In RGB the problem seems to be smaller. And with layer transparency instead of colour transparency it seems to be even smaller, in CMYK, too (not demonstrated in the video).

 

The linked thread tries in ca. 90 posts to shed more light on this. Honestly I don't understand what Affinity actually does, especially since this thread considered gamma and grouping additionally to transparency and colour space and may run into various Affinity issues on its way.

 

Thank you very much for the explanation and the example!

I'm no professional in this field but this to me definitely looks like a bug. If you knew about it, you could easily prevent by keeping a white background layer from the start, but well, I found out right at the end..

What do you mean by "flatten" the layer? I was willing to do that by merging it onto a white layer below, but that's how I discovered the problem

 

[thomaso]

1 hour ago, fpell said:

What do you mean by "flatten" the layer? I was willing to do that by merging it onto a white layer below, but that's how I discovered the problem

Other than "rasterize," the term "flatten" is used in the meaning of "reduce transparency completely" (compare this search). So your choice to merge (> rasterize) the semi-transparent image with a fully opaque layer (> white) does exactly achieve this.

I agree that it is a bug. This is just one of several (e.g. AF-2951) bugs in Affinity since years that affect colour display / colour values / transparency and are sometimes relevant within Affinity, sometimes in exported results, sometimes in both. They sometimes occur together and/or influence each other.

[NotMyFault]

18 hours ago, thomaso said:

The linked thread tries in ca. 90 posts to shed more light on this. Honestly I don't understand what Affinity actually does, especially since this thread considered gamma and grouping additionally to transparency and colour space and may run into various Affinity issues on its way.

The linked thread essentially started with the same bug. As it never was recognized by Affinity, I filed a new bug report with a simplified setup and clearer description.

I misinterpreted the original question as the OP did never state he used a CMYK document (and instead always discussed RGB colors), and during my experiments with RGB color models the alpha handling by Affinity and its unfixed bugs distracted me from the real issue.

The real issue is 2 fold:

1. Affinity treats a white canvas (transparent canvas off) differently from a white background layer (rendering in Affinity, using screenshots ). The info panel ( only available in desktop) gives misleading information 
2. At export, the document setting for canvas transparency gets ignored and the exported file can differ from rendering inside app.

I assume a fundamental design bug in the underlying rendering engine. When rendering CMYK colors, the handling of channels panel gets extremely unintuitive (background is treated as black or white depending on context, wrt to  layer thumbnails, navigator panel, and canvas rendering e.g. selectively activating color channels in color panel.

 

[fpell]

Well, I'm kind of baffled, you'd think this would be one of the first problems to fix for a graphic design software

 

[NotMyFault]

Well, the simple way is to not use any files with remaining transparency. Always add a 100% opaque white rectangle or fill layer on bottom to avoid all these unwanted but easily avoidable surprises.

Except you want to specifically create semitransparent shapes and fully understand that colors are impacted by (existing or non-existing/later added) layers below and out of your control.

Files / layers with partial transparency get always interpreted against a unspecified „virtual“ background, and it fully depends on the app used for rendering if it chooses black, white, any grey level, and how it handles gamma (for RGB) and alpha (any document format).

[fpell]

12 hours ago, NotMyFault said:

Well, the simple way is to not use any files with remaining transparency. Always add a 100% opaque white rectangle or fill layer on bottom to avoid all these unwanted but easily avoidable surprises.

Yes but do it right from the start! 😁