Color replacement brush not working as expected

[banacan]

Hi All,

I'm new to Affinity Photo, having used Photoshop for decades. I'm trying to replace a color in a photo but I'm getting strange results.

As you can see from the attached photo, I have set the primary color as bright yellow. The red shirt image has a transparent background. I select the layer I want to change, choose the Color Replacement Brush Tool, and as I hover over the image the transparent areas show the primary color, but the shirt color does not change to yellow, it turns olive green. 

Here's what the Help file says to do:

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To replace colors by brush:

1. From the Layers panel, select a layer. (If you select a vector layer, it will be automatically rasterized when the tool is used.)
2. From the Tools panel, select the Color Replacement Brush Tool.
3. From the Brushes panel, select a brush of your choice.
4. Adjust the context toolbar settings.
5. From the Color panel, choose a Primary color to replace the color you want to change.
6. Drag the brush cursor over the targeted color.

I've followed the directions but I only get this strange result. What am I doing wrong?

[walt.farrell]

IThe Color Replacement Brush Tool is misnamed. That section of the Help tells you how to use it, but in another section you'll find that it is really a Hue Replacement Brush:

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The targeted color's hue will be replaced with the current Primary color's hue, while retaining saturation and lightness values of the original pixels.

 

[banacan]

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it is really a Hue Replacement Brush

Isn't that what I want? I want to change the color of part of an image. Hue is the "color", saturation and lightness affect hue. It seems to me this tool isn't a hue (or color) replacement tool at all. Rather, it appears to be a color overlay that uses either a hue or color blend mode.

Attached is a file I created with three different colored circles. The yellow circle is the topmost layer and has a 100% opacity with a color blend mode. The red circle is the middle layer with 100% opacity in normal blend mode. The bottom layer is a duplicate of the red layer with a Layer Effect "color overlay" using the yellow as the overlay color. This is identical to the result I'm getting in my first image.

So really this color (hue) replacement tool is not really at all what it claims to be. It really should be called a Color Overlay Brush Tool. That would better describe what it is.

Ultimately, I need to use the recolor tool to accomplish what I want. Unfortunately, there does not appear to be a way to define the hue in RGB or Hex, so it's trial and error. Too bad.

[R C-R]

7 hours ago, banacan said:

Hue is the "color", saturation and lightness affect hue. 

It's confusing but in the HSL color representation, hue, saturation, & lightness are 3 separate & independent properties of the RGB color model.

[Jörn Reppenhagen]

Banacan: For this usage case, you might be better off with a simple HSL adjustment - especially because of the transparent background and the uniform color range.

Select HSL adjustment, choose red color circle, select the picker, click on a bright red area, set Hue Shift to e. g. -62, Saturation Shift to 56, Luminosity Shift to 49 - or to your liking.

Then make sure the HSL layer is selected, invert the layer (color reverts to red), choose the Paint Brush Tool [B], select pure white as a color (255, 255, 255), then paint over the areas you wish to recolor, Opacity controls intensity. Take care not to select "Wet Edges" and "Protect Alpha".

That's essentially the same as Recolor - but the above also works with more complex color combinations (not just with "everything red" things).

Workaround for setting correct hue with Recolor: Set your target color using RGB, then switch from RGB to HSL. The now shown Hue value is the value to set in the Recolor dialogue.

In private: I also find the behavior of the color replacement brush rather strange/senseless - it just doesn't do what it should be supposed to do.

[banacan]

Jorn,

Thank you for your detailed description of how to accomplish this. It's especially helpful for those circumstances where there are multiple color combinations - which I find myself facing all too often. It's too bad that the Color Replacement brush doesn't do what its name suggests. It certainly would be simpler.

Still, in spite of the quirks of Affinity Designer, Photo and Publisher, I'm very favorably impressed with their capabilities. Kudos to the development team!