Control how your color photograph is changed into black and white. Welcome to the fifth article in my Photography Editing in GIMP series!
Article 1: Easy Photography Editing in GIMP
Article 2: How to Crop in GIMP
Article 3: How to Control Saturation in GIMP
Article 4: How to Control Contrast and Lightness
These tutorials use the free photo-editing program GIMP. I am not being paid to endorse the program GIMP--I just really like it!
Convert a Photo to Black and White
There are multiple ways to change a color photography to black and white in GIMP. I will be including the two easiest and most common ways to turn a color image into a striking black and white photograph.
Method 1: Using Desaturate to Change a Color Photo to Black and White
By using the desaturate option, you can change a color photo from this:
Step 1: Open the photo in GIMP. Under the "Colors" tab, click the Desaturate button.
Step 2: Select if you want to Desaturate based on lightness (the shade of the color), based on luminosity (how vivid the color is), or based on an average of the two. I usually like the output better when I desaturate based on luminosity, but you can preview both and choose the one that you prefer.
Step 3: Click OK and save!
Method 2: Using Decompose to Change a Color Photo to Black and White
Although the most common way to change a photo into black and white is to use the "Desaturate" tool, that will often strip the picture of fine nuances in tone and you do not have much say in how the shades of gray turn out. I prefer to use the Decompose option as it allows for greater control over the finished image.
This method can take you from this:
Step 1: Open the image with GIMP and select the "Colors" tab, then select "Components" and finally click on "Decompose."
Step 2: To make this process a bit easier, we are going to open a new dialogue box that will allow us to see the different layers we are using. To do this, select the "Windows" tab, then select "Recently Closed Docks" and finally click on the "Layers, Channels, Paths..." option.
Step 3: Now that this dialogue box is open, we can use it to see the different layers that the Decompose function has given us. Basically, the Decompose function has one layer which turned only the red values into black and white, one layer which used the green, and one layer which used the blue.
As you click on each layer in the dialogue box, you can control what that layer does. Initially, each layer starts off with Opacity at 100%, which means that they are all contributing equally to the final image. By adjusting the opacity, you can control what makes up the final image.
Step 4: If you click on the 'eye' button by each layer in the dialogue box, you can control if you see that layer or not.
Here is what the dialogue box would look like if I only wanted to see the blue layer:
Here is what my final image would look like if I only used the red layer:
Here is what it looks like with only the green:
And here is what it looks like with only the blue:
Step 5: By using the eye button to control what colors you want to be used in your black and white image, as well as using the opacity to control how much of each color will be used in the final image, you can create the best black and white rendition of your original photo.
Step 6: Save!