Newbie:How to turn the whole image black and white and only keep a small section with color.

Software RawTherapee
1

May I know how to use Local adjustment to keep a specific section in color while the outside of the selected section will be in black and white.

3

Have a look at this:

As far as I’m concerned this isn’t a B&W edit that selectively shows a certain part in colour. Why? Because the local adjustment section does not have a black and white tool (like the black-and-white module in the colour tab), so the best you can do is desaturate the image using the colour&light tool, which is a very crude and poor man’s way to create a b&w version.

RawTherapee’s masking, which is used in the excluding spot in the above example, isn’t all that good in my opinion. It will, at times, take a long time and you might need multiple exclusion spots to get the result you want/need.

You can get much better results by exporting both a colour and a black and white edit from RawTherapee, import those two images as layers in GIMP and use a brush (or whatever you prefer) to make those parts that you want in colour to appear.

1 Like
4

@Tan_YK

It’s true that there’s no “black and white” module in Local Adjustments.

But there are ways around it.

Here’s just one example, using 3 RT-spots:

  • the first RT-spot1, in “full-image” mode, where you work on the color image to increase or reduce contrasts, modify colors, play with local contrast, etc. You can use several tools in the same RT-spot, such as “Color and Light”, “Tone mapping”, “Log encoding”, etc.
  • the second RT-spot2, “full-image”, where you reduce chromaticity as indicated by Jacques @Jade_NL using the “Color and light” module.

By modifying the parameters of the first one, you can change the black and white aspect according to the colors, contrasts, lights, etc. modified by RT-spot1 and you’ll see the effects after RT-spot2.

  • Then create a 3rd RT-spot3 for the area you wish to keep in color in “Excluding spot” mode.
    You can use the “Scope” slider in “Excluding spot” to adjust the intensity of what you want. Of course, as Jacques points out, there’s nothing to stop you adding a tool (the one you want, or none at all) to this “excluding spot”.
    image

Of course nothing is perfect :wink:

Jacques

5

Could I suggest GIMP is better designed for doing this. If you need instructions on how to do this feel free to ask.

Also darktable would be able to do this.

Does rawtherapee or ART have a localised saturation control. That might allow you to achieve the look you want.

6

I can easily do the same as with “Abstract profile” (for whole images), in the “Local adjustments” module (Color appearance Cam 16 - SDA - Source Data Adjustments).
This gives you a channel-mixer based on primaries and others tools…

So, with 2 RT-spots, you can have a black and white image background (with channel mixer as a minimum) and one (or more) areas in color.

7

I’ve just made a Pull-request with various improvements to Local adjustments.

  1. modify the “avoid color shift” tooltip as desired in issue #7066 @marter

  2. add a “Black and white” checkbox to the “Color appearance” module - Cam16 - Source Data Adjustments. This provides: a) a channel mixer (primaries), b) Cam16 color adjustments, c) the option of selective or non-selective black and white with Scope. Of course, if you want to select an area that remains colored, use a second Spot with “Excluding spot” (and the desired Scope setting).

  3. add to “Highlights attenuation” an additional choice of “levels R and G and B”. This allows you to retouch shadows and highlights differentiated by “Slope” and each channel, taking into account Tone-mapping .

https://github.com/Beep6581/RawTherapee/pull/7071

Executable - “levels”
https://github.com/Beep6581/RawTherapee/releases/tag/pre-dev-github-actions

Jacques

8

I’ve made a few changes in response to two bugs, including one concerning the customization of primaries.
The “black and white” checkbox is only available in “advanced” mode.

I enclose a screenshot of the possible settings. Basically, you use an advanced “channel mixer” where you vary the primaries, the white point, the dominant color, and so on.
With the use of “scope” you get what you want. Note that absolute black and white is rendered with scope=100.
A second RT-spot, (or third if you want to isolate 2 zones), in “excluding spot” mode, lets you return to the initial image… which you can change by opening an associated tool.
image

Executable (windows, appimage) with text “levels”
https://github.com/Beep6581/RawTherapee/releases/tag/pre-dev-github-actions

Jacques

I ‘merge’ this PR. Now we can say, even if it’s different from the “Black and White” module (Color Tab) essentially based on a channel-mixer, that there’s a “Black and White” module in Local Adjustments : channel mixer on primaries, and Levels RGB with tone-mapping.

@Andy_Astbury1
Andy
You can also test this “Abstract profile” version, but in “Local adjustments”, which is more complete.
LA - Color Appearance - Cam16 - Source Data Adjustments” in ‘advanced mode’.

9

I’m inclined to agree; this is how I do it (and several other similar things). It’s a very quick and easy to accomplish in GIMP.