warmer or colder touch for images

[Winfried]

The Color Balance Transformation does normally a good job to make images to look neutral, i.e. remove color cast in the highlights and in the blacks.
You can also set the mid-tones by klicking on some adequate place, that should be a neutral gray.

But sometimes I want to make an image to look a bit warmer or a bit colder.
In the past with films I used a 81A or a 82B filtera.
These filters are available with the Filter Transformation. Unfortunately the transformation causes a cast in the highlights.
You can overcome this by using the Color Balance Transformation. And you can create your own color balance files.
Shift-Click in an area with an average lightness. Color does not matter. This creates a new pair of "remove" and "add" colors.
First click on remove color and than in the popup color seletion window on 50.2 % gray.
Do the same with the add color. Nothing happened so far. You are just replacing gray with gray :-)

But now you set the add color to HSV mode and under options choose Filterbank. Scroll down to the Filter 81A and click it.
This lightens the image. We are going to fix it with the next step. Now select under options Pastel.
Yo now can darken the filter color to the proper HSV value "value". Since the filter reduced the lightness I suggest a value about 56 instead of 50.2.
That's nearly all. For future use yo can save these setting in a xxxxx.cb-file.
I attached my two files in the zip -file.

Winfried

[tomczak]

There is a somewhat related technique that can be used to change the image tones proportionally to their saturation (i.e. without colouring the whites). This is done by 'rotating' the HSV hexacone in Colour/Selective Correction.

Practically, it requires placing 6, same spin, vectors between all 6 vertices of the hexacone base and then reducing the Amount slider for the right effect. Since those 6 vectors can only turn the cone in one direction, one can create 2 setups (one for turning the cone CW the other for turning CCW), save them and recall them when needed. You can check Modify Colour Wheel to see what it does to the colours at V=100% (it does it to darker colours too, since it turns the whole cone, but you don't get to see it).

[Charles2]

Thanks, Winfried. Your post is also a good reminder that the Color Balance transformation has brightness sliders.

Another solution is that you apply Filter | 81A or 82A through a brightness mask that selects the midtones. The middle tones of a specific image may be above or below the 50 point; build a bell curve as desired. Increase EC as needed.

[tomczak]

Another quick technique to change 'colour tone' without tinting whites and grays:

- extract HSV-S channel to use as mask
- use Filter or Levels&Colour and their Colour Pickers to shift the colours.

[tomczak]

The HSV-S mask can also be created directly in Mask Tool - Color Range dialog (instead of using Extract Channel transformation):

- leave HSV-H and HSV-V ranges all fully included (i.e. all white), and separate one pair of black and white sliders so that it forms a black-to-white gradient from one end of the HSV-S range to another (it takes some fiddling with the sliders to accomplish that).

Extracting the HSV-S channel and using it as mask is simpler and faster, but the technique above allows for interactive adjustments of the mask.