COLOR REPLACEMENT TOOL should be RANDOM COLOR CHANGER?

[SolihullRog]

As a new user, I thought that the Color Replacement Tool looked very useful.  But after a week of trying to use it I was left confused.
I could not understand how it operated. So I decided to conduct a test.
Colour is made of 3 components - hue, saturation, and lightness (HSL).  Each ranges for 0 to 100 and each colour is defined by the combination of the 3.
From its name I would expect it to change each component depending on the required new colour.
But around 4 years ago it was considered that the tool only changed the hue.  So it would better being called the "Hue Replacement Tool".
Last week, I couldn't understand it, so I did a test.  I used Affinity Photo 2.5.7 and its standard swatches along the top row.
I made four stripes - red, yellow, green and blue.
I then applied blobs of the same colours to each stripe - making 16 combinations.  Red on red, red on yellow, red on green etc.

See pictures.
I then recorded the resultant colours.  These were as follows:

Base colours Red 00 100 50       Yellow 09 100 50     Green 99 100 50     Blue 177 100 68 

Arranged as per the displays the resultant 16 colours were

                                00 100 50*                15 92 96                   37 56 63                 09 15 81
                                33 100 24                 09 100 50*                79 100 44               89 78 69
                                51 100 19                   86 100 68                97 100 50*               116 98 75
                                167 12 20                 141 100 79                 161 100 55                177 100 68"

As indicated by the *'s, red on red = red etc.  That's the good news.

I think that the remainder suggest that it should be called the "Random Color Generator".

Where have I gone wrong?

 

[GarryP]

Is this related to the ‘bug’ you reported here on Sunday (and where you got some explanations)?: https://forum.affinity.serif.com/index.php?/topic/225835-colour-replacement-brush-problems-does-it-work-at-all/

If so, please don’t create multiple threads about that same thing as it makes it more difficult for other people to find information, amongst other things.

[NotMyFault]

As explained before: some tool (like CRB) works in color space called HCL or HLC.

This means it is different from regular RGB/HSL definitions you can find on Wikipedia. HUE is a term used differently depending on color space and operation (blend mode) or function (CRB).

• If you would change the hue in HSL mode, the perceived luminosity and saturation changes dramatically 
• to achieve constant perceived luminosity and saturation, HCL works differently 
• The tool is best used for natural, not fully saturated colors. Otherwise the tool runs into clipping issues.

It does not make sense to repeatedly file bug reports for things you don’t understand but work as defined and 100% in line to industry standards.

It would be beneficial if you can describe what effect you want to achieve, so the forum can show you a way how to achieve this.

 

 

https://en.wikipedia.org/wiki/Blend_modes#Hue,_saturation_and_luminosity

Hue, saturation and luminosity

Photoshop's hue, saturation, color, and luminosity blend modes are based on a color space with hue, chroma and luma dimensions. Note: this space is different from both HSL and HSV, and only the hue dimension is shared between the three. See the article HSL and HSV for details.

Unlike all of the previous blend modes described, which operate on each image channel independently, in each of these modes, some dimensions are taken from the bottom layer, while the remainder are taken from the top layer. Colors which end up out of gamut are brought inside by mapping along lines of constant hue and luma. This makes the operations uninvertible – after a top layer has been applied in one of these blend modes, it is in some cases impossible to restore the appearance of the original (bottom) layer, even by applying a copy of the bottom layer in the same blend mode above both.

• The Hue blend mode preserves the luma and chroma of the bottom layer, while adopting the hue of the top layer.
• The Saturation blend mode preserves the luma and hue of the bottom layer, while adopting the chroma of the top layer.
• The Color blend mode preserves the luma of the bottom layer, while adopting the hue and chroma of the top layer.
• The Luminosity blend mode preserves the hue and chroma of the bottom layer, while adopting the luma of the top layer.

Because these blend modes are based on a color space which is much closer than RGB to perceptually relevant dimensions, it can be used to correct the color of an image without altering perceived lightness, and to manipulate lightness contrast without changing the hue or chroma. The Luminosity mode is commonly used for image sharpening, because human vision is much more sensitive to fine-scale lightness contrast than color contrast. (See Contrast (vision))

Few editors other than Photoshop implement this same color space for their analogs of these blend modes.^[3] Instead, they typically base their blend modes on HSV (aka HSB) or HSL. Blend modes based on HSV are typically labeled hue, saturation, and brightness. Using HSL or HSV has the advantage that most operations become invertible (at least in theory), but the disadvantage that the dimensions of HSL and HSV are not as perceptually relevant as the dimensions of the space Photoshop uses.

[NotMyFault]

I assume the confusion comes from a tutorial from Robin Whalley.

Even there you can see that the CRB does not delivers the color chosen in the panel. 
instead it uses only the hue of that color, but keeps the L and C from the pixel layer (using the HCL color mode).

So you get a much darker green than chosen.

 

 

[NotMyFault]

BTW using you first image I get a different result.

when you use the color picker you will see the the hue is correctly transferred.

 

[NotMyFault]

Do you work in RGB color mode and sRGB color profile?

[SolihullRog]

Hi, Thanks for all replies.

To Garry P

I appreciate your views but would observe that many threads become so prolonged that the main messages get lost.

I decided that that my original posts were not very simple, and that a simple matter was losing its point.  My second thread is aimed at getting straight to the point, and I'd be glad for my first thread to be deleted.

To Not MyFault

I'd like you to understand the following:

- I have no particular photo or project that I need to complete

- I have two objectives.  One is to decide whether to persevere with Affinity.  It is rich in functionality but is poor in documentation and seems poor in quality code.  Having invested good money on it I have reservations as to spending more, and need to make a decision.  There appears to be a mountain of functionality but a severe absence of instructions as to how to access it.  e.g.1 The presence and access to the Info panel are almost a complete secret.  e.g.2 The comprehension of the Tools is also non-existent.  Serif was brilliant.  Understanding CRB is key to my decision.  Second is to help Serif/Affinity in their current quest.  Improvement of code and documentation is crucial.

- Your discussion of HCL and HSC is fascinating but is not mentioned anywhere (that I can see) by Affinity.  Your passage on hue, saturation and luminosity is impressive, but is not referenced by Affinity.  It is likely to be of no interest to most users and I don't know how relevant it is.  (Without ego I would tell you that I have 35 years experience as an IT consultant and project manager, and use of more than 200 PC-based apps).

- Simliarly RGB and sRGB.  i don't know the answer to your question, and I hope that I could use Affinity without knowing.

- So then we come to Robin Whalley and the color picker.  I am well-acquainted with Robin's work (which I admire) and the color picker.  Your response defends the situation in terms of "100% of industry standards" and completely ignores user expectations.  Do you think that the CRB does what most users expect it to do?

- My objective is to understand whether the publicity from Affinity matches what they are offering.  Your response persuades me not.  But my current decisions for the future are whether to stay in this space or not.  My current concentration is on the CRB.  Your responses seem to indicate that the application is targetted at VERY keen professional users, and ignoring the other 95% of the market.  (The actions of Save As and Export are indicative in their use of techniques which aren't intuitive for most).

- I may be better-off using an app such as the very good, free Paint.Net?

But thanks anyway.

 

 

[Ldina]

@SolihullRog I didn't read all of the previous comments in this thread, so forgive my laziness.

But, I did test the Color Replacement Brush (or "Hue" brush). I find that it does preserve Saturation and Lightness of whatever I was painting on. Only the Hue changed. If I set the tolerance very high, I can paint a red hue (for example Hue=0) over a gradient (light to dark green, in my test), and hue remains "0" wherever I paint on the underlying gradient. The lightness and saturation vary based on the underlying gradient. If I vary the saturation of my chosen Hue and set it anywhere from 1 to 100%, the result is exactly the same. If the brightness of my chosen He is between 1 and 99%, the result is exactly the same. There is absolutely no change to the gradient if my chosen Hue has a Saturation=0, or the brightness is 0% (i.e., pure white) or 100% (pure black). So, it's a hue brush and strives to preserve the luminosity and saturation of the color you are over-painting. 

The color replacement brush also will have no effect if the underlying gradient is completely desaturated, pure white, or pure black. It seems to need an underlying hue to replace. 

As far as software choices...there are many things I like about Affinity. There are also bugs and things I dislike, and some things that frustrate me. Choices often come down to the type of work one does. If the necessary tools for your workflow are not there, another product may suit you better. For most of what I do, Affinity works pretty well, but I'd still like to see some things fixed. Whether you stay or leave, I hope you find the tools that suit your needs. 

[R C-R]

2 hours ago, Ldina said:

But, I did test the Color Replacement Brush (or "Hue" brush).

It has been mentioned before in other topics about this tool that to avoid a lot of confusion it should have been named the Hue Replacement Brush but I guess it is too late for that. 🙁

[NotMyFault]

8 hours ago, SolihullRog said:

I have two objectives.  One is to decide whether to persevere with Affinity.  It is rich in functionality but is poor in documentation and seems poor in quality code. 

To be honest: in about 10 years since Designer 1.0 the situation got worse every year.

• There are more new or reoccurring bugs than fixed bugs every year.
• Serif almost never answered questions on how things work internally. There are some rare exceptions like Affinity spotlight articles. The most advanced answers were „we are using some kind of standard library“ (to procedural textures internals) or „we don’t know either“ or „we use some open software or free service“ like lensfun DB, littleCMS and refuse responsibility to fix bugs or restriction coming from that end
• Affinity often introduces new redundant functions instead of fixing buggy existing functions.
  • blend range and mask don’t work together. Affinity introduced live luminosity masks, but never fixed the old bug.
  • nested adjustments affecting the alpha channel never worked correctly to groups
  • Some filters like perspective filter don’t respect the opacity when put over other layers in the layer stack.
• some UI elements are so broken that it is torture, and Affinity rejects to improve, e.g. channels panel, editing alpha channel, tab key not working to hop into next input field
• Affinity is British and ignored almost all non-English languages (important keyboard shortcuts only working on us keyboard, local input of decimal point / comma not working etc.
• i could continue for weeks listing broken promises (in the sense of not delivering reasonable user expectations)

if you have such severe doubts and high expectations, better look elsewhere. 

[lepr]

17 hours ago, NotMyFault said:

It does not make sense to repeatedly file bug reports for things you don’t understand

That's a little hostile and unfair. This thread is not a bug report. It is a question about functionality and usage in the forum for such questions, whereas the other thread was a bug report in a bug reporting forum.

[NotMyFault]

1 hour ago, lepr said:

That's a little hostile and unfair. This thread is not a bug report. It is a question about functionality and usage in the forum for such questions, whereas the other thread was a bug report in a bug reporting forum.

Yes, might be harsh but it is triggered by the clickbaiting and misleading title of this thread. This thread is no „innocent“ question, instead inherently contains allegations that Affinity does something wrong. 

COLOR REPLACEMENT TOOL should be RANDOM COLOR CHANGER?

I have an issue with those often aggressive posts as they get more attention than those of users who stay polite and deserve more attention.

[SolihullRog]

Everyone can judge those words.  Thanks to all contributors.