White balance doesn't work correctly

[kaffeeundsalz]

But it would be great to have this as an option!

[lepr]

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[kaffeeundsalz]

To be honest, it would definitely save time if you didn't have to manually mess with the Tint slider after you've corrected the color temperature with the picker. So yes, +1 for this.

[R C-R]

9 minutes ago, kaffeeundsalz said:

I also never considered this to be a bug.

Some may consider the WB picker not affecting the tint slider to be a bug but I think it is just a reasonable design decision. It is hard to explain why I think that but as the Understanding White Balance Cambridge on Colour tutorial mentions, WB adjustments are based on "correlated color temperature," an approximation that resulted in the addition of the traditional secondary green-magenta shift parameter to help correct for light sources that depart significantly from true blackbody radiation.

However, the green-magenta shift is just a secondary approximation. Unless it is 'tuned' to the spectrum of the specific light source, it probably won't work very well, particularly when mixed light sources with different spectra are involved. I also suspect (but by no means am sure) that a green-magenta shift was chosen because once the most common light source that needed WB correction was fluorescent lighting, which gave everything a greenish cast.

These days, not only do we have fluorescent lights with different (but still uneven) spectra, we also have energy-efficient LED lighting, which also do not output 'pure white' light & are equally poorly modeled with a "correlated color temperature,." (Special purpose LED lights with balanced spectra are available but they are very expensive.)

Anyway, the bottom line for me is the tint slider should be something reserved for the user to adjust manually if they want to use it, & never adjusted automatically with the picker. But that is just my opinion.

[lepr]

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[R C-R]

49 minutes ago, kaffeeundsalz said:

To be honest, it would definitely save time if you didn't have to manually mess with the Tint slider after you've corrected the color temperature with the picker.

But it would save time only if it actually corrected for the uneven spectrum of the light(s) in some way that was acceptable as "natural looking" or somehow "true to the original." 

[lepr]

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[R C-R]

5 minutes ago, owenr said:

Tell the image editor developers of the world to stop making colour adjustment tools without consulting you first.

Perhaps I should start by asking you not to misrepresent my comments so dramatically? Never have I said or implied that "color adjustment tools" are not useful. I just question the usefulness of this particular one.

[lepr]

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[kaffeeundsalz]

I must say that I'd find this pretty straightforward: You define an area of the image that, from what your eyes can tell, should be of neutral gray appearance, and the tool adjusts the overall color appearance of the image to match this. Right now, the white balance adjustment can't do this, at least not completely automatically. Of course, the quality of the result greatly depends on the actual lightning conditions at the place and time of the shot and the amount of color cast that is present in the image. Having used Photoshop's white, black and gray point pickers for years (which work as @owenr suggested), I can tell from my experience that it sometimes results in a really unnatural color cast itself, but is often pretty satisfying. So, as is true for every feature of image editing applications, it won't replace the judgement of your eyes.

It's also true that a color cast isn't always equally distributed across the entire image. You might have a light source somewhere in your shot that gives objects a yellow tint only in, say, the lower right corner of the image. In that case, a graypoint picker can only be the first step since you need proper masking techniques to limit the effect to the area of the image that benefits from it. But that's already the case with how Photo's white balance adjustment works right now.

[walt.farrell]

The Affinity Photo Help describes the purpose of the picker in the white balance adjustment as (with my emphasis): Picker—allows you to sample the image to set the white point on which the white balance will be calculated.

So, if I tell the program that some specific point should be white, I would expect the tool to make that point white, with all color casts removed.

Of course, that might not fix the casts across the complete photo, but if it doesn't remove them from my chosen spot then I have to agree the tool is broken. The tint slider really should be adjusting automatically, based on the picker.

[lepr]

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[R C-R]

5 minutes ago, kaffeeundsalz said:

I must say that I'd find this pretty straightforward: You define an area of the image that, from what your eyes can tell, should be of neutral gray appearance, and the tool adjusts the overall color appearance of the image to match this.

But it is not at all straightforward because our eyes do a very poor job of objectively judging what actually is white or neutral gray. We see as much with our brains as with our eyes. Our eyes send our brains color information only from one type of photoreceptor & intensity information from two kinds. Each has different sensitivities to light & are not evenly distributed on our retinas, so we don't even experience color information the same way under bright lights as dim ones & that also varies depending on where we look. Our brains integrate this information & prior experience to form a highly subjective opinion about the color or lack thereof of everything we see.

In fact, almost nothing we see really is a completely neutral gray, which is why photographers serious about objectively accurate color correction use gray cards because they know their eyes can't be trusted for that.

[walt.farrell]

18 hours ago, owenr said:

Yes there's definitely a bug. Whenever I've used the white balance adjustment picker in Photo persona or Develop persona, the Tint slider has never moved off 0%.

When I use the White Balance Tool in the Develop Persona the Tint slider does adjust, for me. (At least, in one test, using the current beta.)

That lends further creedence, I think, to the idea that it's broken in the Photo Persona.

[R C-R]

2 minutes ago, walt.farrell said:

When I use the White Balance Tool in the Develop Persona the Tint slider does adjust, for me. (At least, in one test, using the current beta.)

I think you will find that only works with RAW images, ones that include certain EXIF metadata about color temperature, tone curves, & such created by the camera when the photo was taken. Once developed, tint probably won't change if you go back to the Develop Persona & use the tool again. It is I think related to how RAW images show color temperature in the Basic White Balance in Kelvins until the RAW file is developed, but after that as % if you return to the Develop Persona.

[kaffeeundsalz]

4 hours ago, owenr said:

I was actually referring to white balance tools (having temperature and tint controls) with a single neutral reference picker, not Photoshop's Levels and Curves tools with three pickers.

I know. But when you only use the graypoint picker, you get the same or at least a similar result.

4 hours ago, R C-R said:

But it is not at all straightforward because our eyes do a very poor job of objectively judging what actually is white or neutral gray.

That would only be the case if color was the only reference you have, e.g. in an abstract painting or so. If you have a landscape or a room or whatever scenery, you can tell from the objects that you're seeing what could be a good reference for a neutral color, even more so when you shot the image yourself and definitely know that, for example, some furniture on the photo is actually white in reality. Of course, this won't give you the appearance under the original lightning conditions because the light itself could have a color cast, but I think I already mentioned this and it's not what you're usually after when using the white balance tool (and if so, you'd have to rely on your eyes even more).

[henryg]

Without intending to create any controversy, I too find the Elements 14 white balance correction, via levels, much more effective than Afinity Photo's, but overall it's "no contest" in favour of AP IMO.

[R C-R]

1 hour ago, kaffeeundsalz said:

If you have a landscape or a room or whatever scenery, you can tell from the objects that you're seeing what could be a good reference for a neutral color, even more so when you shot the image yourself and definitely know that, for example, some furniture on the photo is actually white in reality.

Nope. The reality is that our ability to "know" what is pure white or completely neutral in any objective, observer-independent sense is quite unreliable. That is because the references we use are not based simply on the physical properties of the light that reaches our eyes but also on the properties of the sense receptors in our eyes (which are non-linear & have different sensitivities to different wavelengths), how their output is processed by our brains, & what prior experience tells us about how things appear under different lighting conditions. 

[lepr]

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[kaffeeundsalz]

@R C-R, you're getting way too theoretical here. Nothing you say about perception and brains and whatever has anything to do with what people actually intend to achieve with a white balance tool. What they want is to remove a color cast from an image because color casts look ugly (most of the time, they do). There are well-defined workflows to get there. None of these rely on your overly-scientific considerations. In fact, how can any perception of color be objective since we're talking about perception? If that's what you want to discuss, you're entirely missing the point.

[lepr]

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[- S -]

On ‎5‎/‎26‎/‎2018 at 9:51 AM, Sempervivum said:

… There is a significant color fault. I tried the white balance and used the pipette. This is the result:

The photo is still somewhat reddish. I had to correct the remaining color fault by reducing red by use of color balance:

In Photoshop Elements 14 the white balance works fine whithout further measure:

Is this a bug of Affinity Photo or did I do something wrong?

I've noticed this before too, but never actually got round to looking into it further as I normally adjust white balance in DPP during raw conversion.

Comparing images using the White Balance Tool in Affinity Photo to the (non-raw) White Balance Tool in Canon DPP also highlights a magenta cast in Affinity Photo, even though it's using the same sample point:

Original:

Affinity White Balance Tool:

Canon DPP (Non-Raw) White Balance Tool:

[R C-R]

5 minutes ago, kaffeeundsalz said:

Nothing you say about perception and brains and whatever has anything to do with what people actually intend to achieve with a white balance tool.

So what exactly do they actually intend to achieve with these tools? It is all well & good to say is to remove a color cast from an image for one reason or another, but what does that really mean? As you say, it is all based on perception, so how can that possibly have nothing to do with it?

[lepr]

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[R C-R]

Just now, owenr said:

I'm never sure whether you are seriously ignorant or playing at being a fool in order to prolong a disagreement.

So for an old fool like myself, please explain as simply as you can what you would consider to be the "correct" way for these tools to work, one that somehow has nothing to do with the variability of the human perception of the color & intensity of light, or any of the other factors that are inherently subjective about it.

From what several of you have been saying, that should be easy, right?