How To Convert a Color Photo to Black & White in GIMP {7 Options}
Image by Ali Pazani
Black and white photography is a lost art. It wasn’t that long ago when I was shooting with black and white film to express my creative vision. Now that those days are behind us, we’re limited to converting our color images to black and white with GIMP.
Although, “limited” isn’t the right choice of words. We actually have more options for creating artistic black and white images than you ever had with film.
In fact, in today’s GIMP tutorial, you’re going to discover 7 different methods for converting your photos to b&w. Each will provide a new level of artistic interpretations.
Keep in mind that B&W photography itself is a gigantic topic. It will be hard to cover everything in this article. In fact, entire books have been written on the subject!
For this tutorial, you’ll discover the basics of b&w digital imagery. If you’re ready… let’s do it!
Table of Contents
Black & White Deep Dive
Before jumping into the color to GIMP B&W conversion methods, let’s first explore black and white images on a deeper level.
Tone Range
The lack of color hues, when converted to b&w, leaves you with an image of tonal information (and your composition). The tonal range consists of the 5 aspects of your exposure; Black point (pure black), Shadows, Mid-tones, Highlights, and the White point (pure white).
It’s essential to have a vast tonal range before conversion to create striking b&w photos. That being said, not all images convert well to grayscale.
Once you’ve removed the color from your image, the viewer’s attention is not swayed by the hues and is forced to focus solely on the subject (s). This is why it’s crucial to have a good range of tones from the start. Oh, and a strong composition to make it extraordinary.
An image with a strong contrast is another component of powerful b&w photos. High tonal contrast means that the image contains areas of both very dark tones and vibrant bright tones.
If the image lacks a Black and or White point, then your image will be flatter vs. one with these settings. A Black point consists of an area in the image that is pure black. A White point is pure white.
Both points sit on the opposite ends of the tonal range with the Shadows, Mid-tones, and Highlights in between.
In essence, contrast is the corresponding difference in tones between parts of an image. The higher the contrast, the sharper the differentiation between tones. On the opposite end, a low contrast level will have fewer variations.
Monochrome vs. B&W
Image by Thanhhoa Tran. The black and white image was converted using a mono Channel Mixer (Mono Mixer is available in GIMP 2.10+). The second image was created by using a new layer filled with green. Then, I adjusted the Layer Mode to “Overlay” to make the Monochrome version.
There’s a common misconception about b&w images vs. monochrome images. All black and white photos are monochrome. However, not all monochrome images are black and white!
Confused yet? Let’s break down the differences between the two.
Technically, black and white is more grayscale than monochrome. The definition of grayscale is; “an image consisting exclusively of shades of gray.”
On the other hand, Monochrome is defined as an image consisting of one color varying from the brightest to darkest hues. A perfect example of this is the process of developing a Sepia Tone. The hue is the “one” color.
Getting GIMP Black And White Photos
Image by Engin Akyurt
There are various methods for converting to grayscale. Some are better than others, and one isn’t recommended. More on that coming up.
The different approaches to getting to gray comes down to personal preference. Some options could be considered over-the-top, or if you prefer, artistic.
Your visual interpretation may coincide with mine, or you may prefer a different outcome.
Either way, you’ll discover 7 diverse ways for converting in GIMP, and you can decide for yourself which you prefer.
One
Desaturate
Your first option is tried and true… and fast. Let me first point out that this is the least “artistic” method! I’d recommend one of the other six ways for a more creative interpretation.
The process is simple. By utilizing the GIMP Saturation tool (Colors > Saturation), you can instantly remove all colors by adjusting it to 0. Boom, an instant B&W image!
Two
Desaturate Advanced
This method is similar to the first in that you’ll strip the hues (color) from the photo. The difference is, you have five options for controlling how the edit affects the brightness of your image.
To access this tool go to the GIMP menu under Colors > Desaturate > Desaturate to reveal this editing window.
- Luminance
- Luma
- Lightness (HSL)
- Average (HSI Intensity)
- Value (HSV)
Note: In the upcoming GIMP 3.0 version, you’ll have two additional creative options; Layer Blending Modes + Opacity.
Each of the above choices will convert your color images to black and white. However, each will interpret the grayscale conversion differently based on an algorithm.
Note: I’m not a mathematician and prefer visual results vs. deciphering numbers. If you’re interested in the nitty-gritty details of how these modes work, check out this article.
Compare the following images to see each of the five in action. Pay careful attention to how the conversions are rendered differently with each mode.
Original
This first image was converted with Luminance.
Notice how Luma is similar to Luminance.
This time, the Lightness (HSL) method was applied.
This edit consists of a grayscale conversion via the Average (HSI Intensity) mode.
The final image conversion utilized the Value (HSV) option and provides the most dramatic results. Wouldn’t you agree?
Three
Mono Mixer
Image by Владимир, with a channel mixer applied.
The previous conversion method gave you some control of the grayscale interpretation based on a predefined calculation. But what if you wanted more precision and control of the interpretation?
Let’s say you wanted to control how the blue channel influenced the final gray value. Or to have control over the different ratios and weightings from each of the three color channels (RGB) individually.
That’s what is achievable with the Mono Mixer in GIMP. In essence, the “Mixer” lets you be the visual mathematician for results based on YOUR creative vision!
Using a (Mono) Channel Mixer is my favorite method for creating b&w results. It’s the basis for all my grayscale conversions.
Pro Tip:
The Mono Mixer, in essence, is a Channel Mixer. The latter is used to control the RGB channels… in color. The former is used for controlling the RGB channels in Monochrome!
Using the Mono Mixer
To activate the tool, go to the menu under Colors > Component > Mono Mixer. Each of the RGB channels includes a slider for increasing or decreasing the brightness of each color channel.
Adjusting any one of the three to the right will increase the brightness level for that particular color. To the left will decrease the brightness.
- Preserve Luminosity: This setting will preserve the original brightness levels and details (to some extent).
GIMP Pro Tip:
Extreme adjustments may result in banding. If this happens, cancel the edit and convert your image to 16 bits to alleviate any banding issues.
Four
B&W Film Simulation
Agfa 200x was applied for this image.
This image used the Kodak Tmax 400 rendition.
This image utilized the Ilford Delta 3200 Emulation.
Import the free presets to recreate a film look on any image. Note, these are emulations and not exact replicas.
In our digital world, technology allows us to shoot silky smooth images without an ounce of grain. If, like me, you grew up shooting with film you probably have an inkling for grain. Or maybe your creative vision requires an old-school look.
Either way, I’ve developed three presets that mimic film, and you can replicate this by importing these files. Once downloaded, unzip the file to extract the files.
- Next, go to Colors > Desaturate > Mono Mixer.
- Click on the left-pointing arrow and choose “Import Current Settings from File.”
- Repeat these steps for the other two files.
Emulating film wouldn’t be complete without adding some grain! Download this file (it’s huge!) and place your black and white image inside of the appropriate grouped layer (at the bottom).
Five
Color to Gray
If you’re looking for a more artsy grayscale image conversion, this might be it. To open the tool, go to the menu under Colors > Desaturate > Color to Gray. Once the new window opens, you’ll see 4 choices for creating your black and white image.
- Radius: Per GIMP, this takes the radius in pixels into account when deciding which colors map to gray values.
- Samples: This determines the number of samples to do per iteration by looking for the range of colors in your image.
- Iterations: This will reduce the amount of noise created with the previous settings.
- Enhance Shadows: When enabled, details (and contrast) in the shadows are boosted at the expense of noise (grain).
One thing to keep in mind when utilizing Color to Gray to your image is that it’s an intensive tool requiring lots of computer resources. In other words, GIMP is going to be slow in executing your adjustments!
Even with 32GB of RAM, each time I adjust a setting, it takes around 20 – 30 seconds for GIMP to execute! Also, the bigger your image file, the slower it will be. If you know the final size required for output, I’d recommend doing that first. Often, my final output is smaller than the original file out of the camera.
If you require a large image file for output, work on a smaller file to find the perfect settings for it. Once you find a rendition to your liking, save the settings as a preset. You can then apply that preset to the larger image!
Six
Monochrome
Image by Ali Pazani
You’re now going to discover how to create a monochrome vs. a pure grayscale photo. Under Colors > Desature > Sepia, you can instantly add a sepia tone to your image.
But what if you want a different hue? This can be achieved by filling a new layer with your color of choice and adjusting the Layer Blending Mode. Oh, and you’ll first need to convert the image layer to b&w with your favorite technique.
Seven
Spot Coloring
Discover how I made the color of the eyes different in this image by clicking here. The secret is using the Paintbrush tool on a Layer Mask!
This is an old-school technique that you either love or hate. Spot coloring is the process of converting a part of your image to grayscale and keeping the rest in color. In the good ‘ole days, I’d practice this technique by hand coloring a black and white photograph.
The method for achieving these photo effects in our digital world requires multiple steps…
- First, duplicate the original image layer and rename it to “Grayscale.”
- Next, apply your favorite color image to b&w conversion technique.
- To strategically remove the grayscale from portions of the layer, add Layer Mask filled with white.
- Grab your Paintbrush tool, set the Foreground color to black, and paint over the image that should be in color.
- To stylize the edit more, adjust the layer by changing the opacity and or use a Layer Mode. Make sure to deselect the Layer Mask before making these changes.
What's Next?
Have you created the perfect color image to black and white conversion with GIMP? I’d love to see your masterpiece!
Here’s how… join the best Facebook group this side of the Milky Way to share your artwork with thousands of other photographers. Oh, and it’s a great place to learn from like-minded artists!
Do you have a stellar idea for black and white conversions? If you’d like to share, let me know in the comments below.
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