Image menu and mode followed by CMYK
Go to the brush tools in the toolbar
Apply stroke in CMYK color mode etc
To go back to RGB, just go back to the same image menu and select the RGB option
Tutorial on how to use Photoshop brushes with image modes (such as RGB and CMYK and LAB etc) to create stunning color designs . Photoshop brushes can be used in any image mode / color mode. You can use the Photoshop brushes in image mode RGB as well as image mode CMYK and LAB. You can apply brush strokes in CMYK and then convert back to RGB image mode. You can apply Photoshop brushes to individual channels in the image modes of CMYK and LAB to create interesting designs. You can also use the Photoshop brushes to great effect with image mode RGB and 32bit per channel. The resulting conversion back to image mode 8bit RGB via HDR toning creates some interesting Photoshop brush effects. This tutorial shows you a number of steps of converting files to other image modes and using the Photoshop brushes in those image modes. The tutorial also shows the result of HDR toning from image mode 32bit to 8bits per channel. You can use the Photoshop brushes in CMYK / LAB and other color / image modes / models as well as RGB.
You can also apply the brush stroke to CMYK's color channels
select individual cyan, magenta channels via the channels panel.
Add brush strokes
You can use the dabs in CMYK to create some truly extreme color effects, especially combined with the black channel.
Apply the brush stroke to LAB image
You can also apply the strokes in different colors to LAB channels L and AB channels via the channels panel
The generated dabs seem to be a lot more subtle in LAB mode, more diffuse.
The RGB option is available for 32 bits channel mode via the image mode menu. In 16 bits / channel RGB LAB CMYK are available for the strokes. Some of the filters are not available in the 32bits etc.
I have been using the default standard soft round brush stroke. With 32bit and 16bit channel, you also have the added feature of the HDR toning when you convert back to RGB 8bit so the results can be displayed on web pages etc and the HDR toning has a large number of presets as well as settings to either create very close to the same result Visually) in 8bit and 32bits per channel but you can also use the settings to invert / grayscale / added saturation etc.
The result can be very different from the actual generated brush strokes.
3. link brushes
1. Image modes