Wrong RGB values in the Colour panel / Info panel

[pano]

Document is in LAB/16 format (CIELAB D50 profile)

I use the LAB color 71,39,76 but the info is telling me that is RGB 252,143,11 while the Colour panel is telling me that the same color is 255,143,6

I can't understand..

When I'm working in RGB16 / sRGB format, what's the White Reference Point for Lab colors? I would like to use D65

[walt.farrell]

1 hour ago, pano said:

I use the LAB color 71,39,76 but the info is telling me that is RGB 252,143,11 while the Colour panel is telling me that the same color is 255,143,6

Do you have the Lock enabled in the Color panel?

If so, does it help if you Unlock it?

[pano]

Nothing change if I lock/unlock the color.

The RGB Red channel is saturated so I would expect to see a different color onscreen, but this is not happening even with a 10 bit display output

[Oufti]

3 hours ago, pano said:

the info is telling me that is RGB 252,143,11 while the Colour panel is telling me that the same color is 255,143,6

What do you mean by "the info (panel)"?

And what OS are you using?

[pano]

I'm using Windows 11 22H2 with all updates

Please see the screenshoot attached

 

[v_kyr]

See the Info panel customization setups ...

 

[pano]

By changing the info panel to LAB things are even more weird, also the LAB info is not matching with the LAB color

[v_kyr]

8 minutes ago, pano said:

also the LAB info is not matching with the LAB color

You may have to sample it from location, in order to refresh it, as it might otherwise show up older values. - This is on APh v1, don't know if things have changed here for v2 ...

 

 

 

[pano]

Yes, I have sampled it again, but same story. Seems from your video that also v2 is broken. This is a super important bug that should be fixed, if we can't trust color data, the software is worthless for many applications.

I'm now worried with the color accuracy of what is shown on the monitor.. sampling the color with the paint screenshoot tell me that the info panel is right and that the LAB color I picked in the colour panel was somehow changed.

[v_kyr]

7 minutes ago, pano said:

Seems from your video that also v2 is broken.

I use V1 and the top color panel of course doesn't autodynamically update, that changes only on user interaction (so on force) by setting up other values and when using it's color picker etc. But in the Info panel "sample from cursor" should usually continiously sample the color under the cursor from the doc canvas (and only from that one, as it doesn't sample from panels).

[thomaso]

Inconsistent colour values in various UI places have been reported for V1 quite few times, here some examples …

Tagged as "afd-3210" (2018–2020): https://forum.affinity.serif.com/index.php?/search/&tags=afd-3210

Tagged as "afd-3590" (1 thread only, 2019):

Tagged as "afd-3236" (1 thread only, 2019):

For V2 (not tagged yet):

[pano]

Why developer don't care? This seems serious

[thomaso]

Maybe because they judge possible workarounds as sufficient? – For instance …

On 5/3/2023 at 7:10 AM, lepr said:

Yes, there can be an initial naive colour conversion instead of colour managed conversion in the little colour editors throughout the apps. The linked thread below involves that problem. Essentially, the user must be careful to ensure a little editor already has its sliders in the actual mode of an existing colour's definition before opening the editor, otherwise the editor will start with a naive non-colour managed conversion to the editor's mode.

[pano]

I can't see the workaround working in my case

[lacerto]

16 hours ago, pano said:

I use the LAB color 71,39,76 but the info is telling me that is RGB 252,143,11 while the Colour panel is telling me that the same color is 255,143,6

I am not sure but I think that the picker values in the Info panel are display RGB color readings converted to document color mode and profile (and then from this to "secondary" color profiles specified in the Info panel), which would explain differences in readings between the Color and Info panels. Color panel, when the lock is turned on, will retain the actual color definition and perform direct profile based calculations not affected by display/rendering color values.

Note too that when using Photo, the underlying RGB color profile to which the Lab values are converted to, are determined by the RGB color profile defined by Preferences > Color at the time the document was created (and is not affected by changes made afterwards in Color Preferences contrary to e.g. Photoshop). You also cannot change the underlying RGB color profile in Photo like you can in Affinity Publisher and Designer (by using File > Document Setup > Color, switching the color mode and specifying the profile, and then switching back to Lab color mode), so the RGB readings that you get in a Lab-based document in Photo are bound to the document profiles that were active at the time the document was created.

[pano]

Attached my settings.

Let's suppose that the LAB color 71,39,76 is converted to sRGB with D50, we will get 255,143,5. By using D65 we have 255,142,7. There is no way to get 252,143,11 unless a weird RGB Model / Gamma / Adaptation is used internally by Affinity.

 

[thomaso]

13 hours ago, v_kyr said:

You may have to sample it from location, in order to refresh it, as it might otherwise show up older values. - This is on APh v1,

Interestingly, apart from the deviation between Colours panel & Info sampler, not only I get different value deviation sampled than you (with the same sRGB profile), also there seems to be a value deviation between layer types (pixel | vector):

1 hour ago, lacerto said:

I am not sure but I think that the picker values in the Info panel are display RGB color readings converted to document color mode and profile (and then from this to "secondary" color profiles specified in the Info panel), which would explain differences in readings between the Color and Info panels.

• And/but what if app prefs, document and Info panel are set to the same profile? (as in the clip above)

• How do you specify a "secondary" profile in the Info panel ? Is this a new V2 feature? (And for what use / as kind of softproof?)

Also the Info panel seems not to have the options of the Colours Panel for 8 / 16 bit and percentage (> e.g. for larger numbers / more value precision (missing decimals in 8 bit)). Though, in V1 the UI design makes it hard up to useless to choose 16 bit for sliders by its value field size for only four instead of the required five digits, regardless of panel width.

.

[v_kyr]

Quote

For testings and comparisons in Affinity you can choose in the Info Panel:

1. RGB / adobeRGB
2. Lab

and then load in (starting color swatches begin on page 3) of this document, which contains patches with indicated Lab-, sRGB- and aRGB-values. Since the colors in this doc are entirely coded in Lab ...

• http://docs-hoffmann.de/swatch16032005.pdf

See related ...

 

[lacerto]

9 hours ago, thomaso said:

• And/but what if app prefs, document and Info panel are set to the same profile? (as in the clip above)

• How do you specify a "secondary" profile in the Info panel ? Is this a new V2 feature? (And for what use / as kind of softproof?)

I tested this so that the document color mode was Lab/16 (with D50 profile). I consider "Lab" color mode then the "primary" color model within Color and Info panels, and all other models as latent or "secondary". The conversions within Color panel seem to happen more or less expectedly based on profiles and (with lock turned on), based on fixed definition that is retained (there are rounding inaccuracies and minor differences compared to conversions performed by Adobe Color Engine, but they are insignificant).

But there are inconsistences in the values between the Color and Info panels, which I cannot explain, especially when using secondary color models (and which do not exist e.g. in Photoshop where I can also assign the display color profile as the RGB working profile to get exactly matching color values with the system color picker (grabbing display color values) and conversions performed by the app color pickers. These issues might be related to problems that Affinity apps have when rendering Lab based colors since it seems that the gamut is limited and cannot benefit the full display gamut. And as you mentioned, the Info panel only supports 8-bit accuracy so that may also cause minor errors (e.g. when using Lab color mode and displaying Lab values in the Info panel). 

[pano]

So... here some additional info and insight

White Reference: D65 -> LAB color 71,39,76 -> RGB 262.9,142.0,7.4 (out of sRGB gamma)

Photoshop -> LAB color 71,39,76 -> LAB 70,36,70 -> RGB 247,143,30

Affinity Photo -> LAB color 71,39,76 -> RGB 252,143,11

Seems there is a different handling for out of gamma colors, they are probably not just clipped to preserve the hue.

Good communication from Serif would be to create a white paper or document all this stuff, otherwise is weird you define a color and is changed without telling anything. Photoshop tell you that your LAB color is changed as well.