Believe it or not, there is more than one “right” way to change a color photo to monochrome (Black and White). This post discusses three ways to remove color from a photograph and some reasons why you would want to choose a specific method. Remember that there is always more than one way to accomplish an effect in GIMP and experimenting will help you find the result you’re looking for.
For these methods, I will assume that you have GIMP installed and that you are capable of finding and opening your image before attempting the changes.
To see larger versions of the images, click them so they can load in a new tab.
Link to free online stock sample image used in this post: http://cdn.morguefile.com/imageData/public/files/j/jade/11/l/1352768821hxoms.jpg
Feel free to comment with your experiences in making a monochrome image in GIMP. I look forward to learning how you make your monochrome images.
Method #1 – Desaturate Feature
1. Open your color image in GIMP
2. On the Menu bar, click the Colors menu item, then click Desaturate.
3. You will receive a dialog window asking how GIMP should handle shading the greys. Choose Luminosity and click OK.
4. Your color image will now appear in black and white.
5. To save the file, click the File menu, then click Export and declare the file name, location and format. Note: If you choose Save or Save As, that saves the entire project, not just the image file. In this example, we are saving the file and do not wish to save the project.
6. Finally, on the Export Image dialog, choose your quality and click Export. Your file will be in the path you specified in step 5.
7. Procedure complete.
Method #2 -Set the Image Mode to Grayscale
1. Click the Image Menu.
2. Click Mode, then click Grayscale.
3. Your image will now show as a monotone image.
4. Export your file, if you want.
5. Procedure complete.
Method #3 – The Channel Mixer
This method is the most advanced and allows for the most control. By adjusting the red, blue and green values, you can really take control of the monochrome output of your image. You can really experiment with your image to find the best way to present it in monochrome.
1. Click the Colors Menu, click Components, click Channel Mixer
2. On the dialog window, click the Monochrome and Luminosity checkboxes to enable them
3. Adjust the R,G,B values. They must total to 100 when combined.
4. For starters, set Red at 30, Green at 59 and Blue at 11 to see what greyscale would most likely render as a starting point. These values are different based on your source image.
5. Experiment with each color channel to see how the color change affects the preview display image.
6. Click OK when finished to apply your changes.
7. Export your file, if you want.
8. Procedure complete.
Helpful links for reference: