Make your image black and white in GIMP
There are different ways to turn an image into mono using GIMP. I will show you how you can do it in just a few clicks as well as using option with more freedom to fit your preferences. One software, four different ways, let's see which one you will like best.
If you don't have GIMP yet, you can download it for free from here.
FX-Foundry script pack used in Method 3 can be downloaded from here and then it needs to be installed in GIMP).
Open your image in GIMP by dropping it right on the GIMP canvas or going to File / Open / find it in your folder/ Open.
I use this method of B&W conversion when I don’t really care about the final result and just need to get rid of colours in the image for the further post processing.
Go to Colors / Disaturate. Now choose Lightness, Luminosity or Average, see which option you like more, then click OK see fig 1.
I don’t personally use this method, but I decided to mention it anyway.
Go to Colors / Hue-Saturation and move Saturation slider all the way to the left (-100), then click OK see fig 2.
Go to FX-Foundry / Photo / Effects / Eg Black and White. You will find 8 options for B&W conversion. The huge disadvantage of this script is that it doesn’t have an instant preview option. To be able to see the difference between all 8 options, I suggest you to try all 8 conversions, but make sure every time you want to make a new conversion you select your colour image. This way script will know with which file/layer it should work and will create a copy of it see fig 3.
Use Eye icon on the left of each layer to activate and deactivate it to see which way of conversion from those 8 you like best. In my case (for this particular image) I prefer “B&W + ORANGE filter”.
Go to Colors / Components / Channel Mixer. Click on Monochrome and Preserve Luminosity to activate them.Channel mixer is great in the way that it firstly has an instant preview of the results and secondly it gives you the power of doing even the finest adjustments of B&W conversion.Using this method you decide for yourself which colour should be more prominent in the image.
You have three colours to work with: Red, Green and Blue.Default setting is: Red 100.0, Green 0.0, Blues 0.0 see fig 4. As a rule of thumb you should set you numbers so that in total amount is 100.For example: Red 50.0, Green 15.0, and Blue 35.0 (50+15+35).You can also set numbers at minus (-25, -30, -90 etc.), but be careful to not to overdo as it may create a very fake look to the image.
Now you know how to turn an image into Black and White with different results using GIMP. Play with your image, try the options I showed you and choose your favourite one.
Hope you enjoyed this tutorial!