Looking for a quick, easy, and effective way to steal color grading from a photo using free software? In this tutorial, I outline the most effective way to steal a photo’s color grading using any software – free or premium – using the free photo editing software Darktable. This method will work with JPEG photos or RAW photos (Darktable is primarily a RAW processing software, but can handle a variety of filetypes including JPEGs).
You can watch the video version of this tutorial below, or scroll past the view for the help article version (available in 30+ languages using the languages icon in the upper left corner of this page).
Step 1 : Import Your Images Into Darktable
First, you’ll need to bring the images you want to use into Darktable.
To do this, navigate to your Lighttable tab if you aren’t there already (usually you are taken to this tab by default when you first open Darktable – click on the “lighttable” text, outlined in green in the image above). Once in the Lighttable tab, click the “import” dropdown arrow (red arrow in the image above). Click “Image” (blue arrow) to select images from your computer.
Navigate to the folder on your computer where your images are saved (in my case, my images are in my Downloads folder). Click on the image you want to select, then hold the shift key and click on any other images you’d like to select if selecting multiple images from the same folder (red arrows in the photo above show the three images I opened for this tutorial). Once your images are selected, click the “Open” button at the bottom of the dialogues (blue arrow).
You’ll notice all the photos I’m using for this example are JPEGs, but you can also use any of the filetypes supported by Darktable.
Your images will usually open in the Darkroom tab (outlined in green in the image above), and if you opened multiple images they will display as thumbnails in what’s called the “Filmstrip” area towards the bottom (red arrow). You can double click on any of the thumbnails to open that image into the Darkroom tab – which essentially means that is the image you are now working on.
Step 2: Activate Color Mapping Module
Now that we have the images we want to use for this effect opened up into Darktable, we’ll want to activate the “Color Mapping” module on the image that we’re stealing the color grading from.
To do this, I’ll navigate over to the “Effects” tab (red arrow in the image above – assuming you are using Darktable 3.4 or later. In earlier versions of Darktable, this feature was located in the “Color” tab).
Once you’re in this tab, you’ll likely need to scroll down (using the scroll bar on the far right side – red arrow in the image above) to find the “Color Mapping” module. Once you find it, click this module to activate it (green arrow).
When you click on this module to activate it, it should expand as shown in the image above. The “power” icon should now be highlighted, indicating it is activated. If, for whatever reason, this icon isn’t highlighted, click on it to make it active (red arrow).
You’ll see there are two main areas in this module, the “source clusters” and “target clusters,” and that each of these areas has a set of grids (outlined in green in the image above). These areas will be where our “source” image colors and “target” image colors appear. The source image is the image we are stealing the color grading from (the main image in the photo above), and the target image is the final image where we will be adding the color grading we stole from the original source image (either of the images denoted by the blue arrow in the image above – these are the target images).
The “acquire as source” button will “steal” the colors from the source image, and the “acquire as target” button will determine the colors from the target image that you are swapping out.
Below the “source clusters” and “target clusters” grid are three sliders. The “number of clusters” slider (blue arrow) allows you to increase or decrease the number of color clusters you’re using to map the colors in your source and target images. All you need to know about this setting is that typically the greater this number is, the more colors you are grabbing from each image and therefor the more diverse the set of colors are going to be. As a result, the “color grading” effect will be more subtle in the end. On the other hand, when this number is lower, there will be less colors used to create the effect and therefor the effect will be stronger.
Again – a higher number of clusters creates a more subtle effect, and a lower number of clusters creates a stronger effect.
The color dominance slider (green arrow) determines how the target image’s colors are swapped out with the source image’s colors. When this slider is set to 100%, this means that dominant colors from the target image will be swapped out with dominant colors from the source image. For example, if red is a dominant color in the source image, and green is a dominant color in the target image, then the dominant green color will be swapped out with the dominant red color. When this slider is set to 0%, similar colors between the source and target images will be swapped out.
Finally, the last slider, the “Histogram Equalization” slider (red arow) allows you to make the histograms of the two images more similar. Technically speaking, this means the tonal contrast of the two images will be made more similar. More on this later.
Step 3: Acquire and Apply Colors for Stealing Color Grade Effect
Now that we have the Color Mapping module activated and know what each area of the module is for, we can now steal the color grading from our source and add it to the target image.
First, you’ll want to set the value of your “number of clusters” and “color dominance” sliders. I recommend going with a value of “3” for number of clusters. You can set the color dominance slider to whatever value you want based on the information I gave above about this slider.
Once I have my desired settings, I’ll click the “acquire as source” button (red arrow in the image above). You’ll now see that my “source clusters” grid (green arrow) is filled with colors. These are the colors we’ll use for our color grading.
Now that we have our source colors, double-click on the target image using that image’s filmstrip thumbnail (red arrow in the image above). This will open that image into the Darkroom tab. Navigate back over to the Color Mapping module. The module may be blank once again (i.e. the source clusters colors don’t show up). Simply click the “reset” button/icon (green arrow) and the source colors you selected from your source image will repopulate.
Once your “source clusters” colors repopulate, click the “acquire as target” button. This will populate the “target clusters” grid with colors from your target image. These are the color that will be swapped out for the source colors. Looking at our target image, you’ll now see it contains a more similar color grading to our original source image.
You can now use the “equalize histogram” slider (red arrow) to adjust the histogram of your target image, making it look more similar to the source image.
As you can see in the image above, the new color grading on the target image colors doesn’t look great – the skin tones look very red.
You can always fix this by returning back to the source image, adjusting the “number of clusters” and “color dominance” sliders to new values, clicking the “acquire as source” button, and then returning to the target image. Once on the target image, click the “reset” button again, then click “acquire as target.” This will once again swap your colors out, but with slightly different settings and therefor a different result. To put it more simply – repeat the steps covered throughout this article, tweaking the settings until you get the final color grade you like.
Above is an example of tweaking the settings for a different result. In this example, I used 4 clusters for a more subtle effect. I also adjusted the histogram equalization slider to a little above 60%.
That’s it for this tutorial! You can check out my other Darktable tutorials on my site, or watch any of my GIMP or Inkscape tutorials.