Some examples of selective desaturation for artistic effect. All photos taken with the good ol’ Kodak V1003 and processed in GIMP by turning down saturation on all but the intended colour.
It is interesting to note that in “Red” some brown and orange tones were retained, because they are a form of red.
This is my favourite. The old (’69 or so) GMC bus abandoned to use as a storage facility and looking forlorn indeed. There is some residue of colour in the weeds in front of it of course.
Here a couple of abandoned water pressure tanks lay in the weeds awaiting eventual recycling. This one brings up the issue of just what colours can be eliminated this way: the green of the small pine sapling is completely gone. Trying to retain green is another matter, as green is often not green but yellow and blue (or rather cyan in the weird world of photo colours) put together. Thus removing the yellow and/or cyan/blue results in a loss of green tones that you may prefer to keep.
This shows up in processing other colours too, if they are comprised of blending two tones. Sometimes removing the colours doesn’t make any noticeable difference:
In the second version magenta, cyan, and yes green have been removed. It’s hard to tell the difference, isn’t it? On a more complex pallet the secondary colours have more effect.
If you set out to do this yourself, you have to keep in mind what primary colours are in the image and try to envision what it will look like with some removed. Some cameras, by the way, have the ability to do this single-colour rendering within them. It is usually buried deep in the menu system, and of course shooting that way initially means eliminating any ‘normal’ version of the picture which might look better (although sometimes this is an in-camera post-shoot processing which retains the original; check your manual carefully).