Affinity Photo white balance picker does not produce the expected results (v2.0.3 Windows)

[Horseflesh]

I'm having a hard time using the white balance tool in Photo to correct lighting color cast. Here's an example. The image is not mine, it's just a good example I stumbled on... A photo of a piece of paper with colored ink, but with a strong yellow cast from the lighting. 

In Affinity Photo I used a White Balance adjustment layer, clicked the Picker button, and sampled a spot on the paper. The yellow cast was somewhat reduced, but not eliminated. 

In Photoshop, I did the same thing with the grey point dropper. The yellow cast was eliminated as I expected. The image has other problems now, but isn't it more correct? I cannot get similar results in Affinity Photo unless I twiddle the sliders myself. This just doesn't seem right.

This test image is dramatic and probably not really salvageable, but it illustrates the problem. I am unable to correct even small white balance problems in Affinity Photo via the picker.  Basically, a huge white balance problem receives a small correction, and a small white balance problem which should be fixable receives little or no correction. 

If I am misunderstanding this tool in Affinity Photo, how can I click to pick a grey point as is possible in Photoshop?

(While this sample was done in v2.0.3 for Windows, it has worked like this since my v1 days.)

[RichardMH]

Photoshop does seem to have made a mess of the other colours?

[Horseflesh]

1 hour ago, RichardMH said:

Photoshop does seem to have made a mess of the other colours?

It has -- I think this image is uncorrectable because the cast is too strong. But Affinity Photo seems more wrong than Photoshop.

And if you have a slight color cast, AP can't correct that either. To me it seems like the white balance picker doesn't work at all, not just in this strongly colored image. 

 

[v_kyr]

40 minutes ago, Horseflesh said:

And if you have a slight color cast, AP can't correct that either. To me it seems like the white balance picker doesn't work at all, not just in this strongly colored image. 

Sometimes you get better results when dragging it over areas (instead of a single point sel-click) and so let it determine the average whites instead. - Though I agree that in APh black & especially gray point selection is badly missing here!

I recall for the PS white balance & curves adjustment, that one gets quite good (nearly correct) results, when making use of graycards and color targets during foto shootings.

[Horseflesh]

Yeah, Photoshop nails it if you're careful to have a proper grey reference available. I've not seen APh perform nearly as well. 

I'll try dragging around in APh, thanks!

 

[RichardMH]

I suspect you have coloured paper rather than a colour cast. 

vectorscope seems to show that

[Horseflesh]

The original photo showed a desktop including objects I knew to be white, all lit with yellow light like a sunrise. So, I think the paper is white, but since it wasn't my photo I can't prove it. 

But the behavior of the white point picker seems to be poor, regardless. Even if it was colored paper, the white point picker it should yank the image colors to the point where the paper was neutral, right? That's what that tool is supposed to do, it's our job to use it wisely. 

The issue I am trying to report is not that this image cannot be corrected, but that I've never seen the tool work as I would expect with any image. 

 

[v_kyr]

It's probably better to test on defined samples, like for example ...

 

... in order to see how the APh white balance behaves then.

[Horseflesh]

Here's a pic of a model holding up a white balance card. It's from this article which shows how to use Lightroom.

https://lightroomkillertips.com/using-gray-card-setting-white-balance-lightroom/

I don't care for APh's corrected version below. But, this is a jpeg from a web site, not a raw file that I shot myself. 

[Horseflesh]

I am 100% prepared to be wrong on the internet if anyone can explain how to correct white balance in the Affinity suite.  

[Conrad Hoffman]

IMO, the white balance picker in Affinity Photo isn't implemented correctly. When you click on a neutral grey area, the resulting RGB values should be identical. IOW, both the temperature and tint slider should have been adjusted for neutral grey. Right now only the temperature is corrected. You'll see the R and B values have been matched. They don't match green, so you then have to adjust the tint slider until they do. This is also a bit non-obvious because when you slide towards green, it doesn't increase green. It decreases red and blue. Regardless, you can usually slide to get there if the balance isn't terribly far off to begin with. (I don't give a darn about the way the image looks after this- the goal is to match RGB for a neutral area. After that, tune as needed.)

I'm sure doing this correctly has to take into account the absolute values and try not to push the image into clipping. I have other programs that implement this correctly and AP does drive me a bit nuts because it doesn't do the whole job automatically. IMO, that's kind of what the picker is for. Strongly suggest it be fixed for the next release. If there's some reason to keep the current behavior, there should be a check box to select the way you want it to work.

Caveat- I think I've described this correctly, but somebody should confirm it!

Edited January 12, 2023 by Conrad Hoffman
more info

[Horseflesh]

I've seen the tint slider move, but it never seems to move enough to create the result I would expect. 

I am also glad to hear that I am not alone in thinking something isn't right, thanks @Conrad Hoffman

[Lisbon]

35 minutes ago, Horseflesh said:

I've seen the tint slider move, but it never seems to move enough to create the result I would expect.

To be honest, I also think I've seen that slider move before. But in general i agree with @Conrad Hoffman. If the white balance picker only adjusts one slider it becomes hard to achieve neutrality. Sometimes, you can almost achieve neutrality with only one slider. But thats just luck.

36 minutes ago, Horseflesh said:

I am also glad to hear that I am not alone in thinking something isn't right

Believe me, your not the only one. Theres is even an old topic where the author mentions several softwares where the picker actually neutralizes the color.

---###---

The white balance adjustment could be such a great tool...

The picker should be more than a picker. It should allow dragging and making a selection and based on the average of that selection fix the white balance.
Selecting the entire graycard is a good example.
But why stop there, why not select all the image? Sometimes averaging the entire image gives better results than trying to pick a color that should be neutral.

"Pro Contrast" from "Color Efex Pro" has a slider to fix color casts. Yes, a slider!
After adjusting the white balance with the picker there should be a fade slider. Sometimes the best overall result isn't achieved by completely neutralizing a specific color, but something in between.

[MEB]

Hi @Conrad Hoffman, @Horseflesh,
Try to use the White Balance tool in Develop Persona with a RAW image and check if it does what you expect (it should). Currently there's a bug that prevents the White Balance Tool to work properly both in Develop and Photo Personas when working with regular/already developed images (pixel layers) - it only adjusts the temperature (not the tint). This issue should be fixed in the next patch/update (2.0.4).

[Horseflesh]

I'll play with a raw file but the bug fix is great news, thanks @MEB! 

[Conrad Hoffman]

Yes, just tried a raw file and it works as expected. Never tried that before as I only do a few specialized things with raw files. Cool! Will be happy when 2.0.4 is released- thanks!

[Horseflesh]

Yeah, I admit I only do raw stuff in Lightroom -- because if I have 1 raw file, I have another 50 and I need to import the shoot. And as much as I like the Affinity suite, that ain't its strength. 

[user_0815]

In Photo it can be done as in most other apps. But as Conrad Hoffman says, the green-magenta slider doesn't move when using the picker. In that case, place an info-point on a neutral area and adjust to equal R G and B values (in the screenshot that is RGB 211).

Keep in mind, not every colour correction is white balance. In most cases there is colour contamination where light bounces off objects and mixes in (or other non-neutral light sources). That means, a neutral grey/white reference needs to be free of such in order for the WB-picker to give accurate results.

In your first example, you'll need to know whether the paper is pure white or not.

In my experience the auto-Levels works good to get a neutral looking image. (In the top tool bar.)

For nasty colour-casts I still prefer the fill layer in Divide blend mode.

If it needs to be super detailed, colour balance or selective colour are the tools of choice.

[Horseflesh]

Great post, thanks @user_0815.