: Convert to four hues while preserving tints in Photoshop I would like to reduce the number of hues in my image from the full range to only four - BUT - I would like to preserve tints/lightness.

@Vandalay110

1. Convert the RGB image to HSB

Use Filter > Other > HSB/HSL and select Input mode: RGB and Row order: HSB.
This will make the image look very strange but it allows us to manipulate the hue separately from the saturation and brightness using the image channels.

2. Reduce the number of hues

The Red channel will now contain the hues for all pixels in the image. You want to quantize these into your four selected hues. This is the hardest part. One way to do this would be to copy the content in the red channel to a new image and set image mode to Indexed color and create a custom palette with your hues mapped to the corresponding black and white values. Then paste this image back into the red channel.

3. Convert back to RGB

When you have reduced the number of hues you apply the HSB/HSL filter again but with reversed input/row order setting to complete the procedure.

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@Berumen635

It's not converting many colors to 4, but achieving 4 colors with the same tint? Open the first color in your color picker. Left and right changes hue. Up makes tints, down makes shades. Go straight up from your color a specified distance. I don't know how to specify the distance, by eye and hand is how I do it. If your original color is halfway up the the chart, pick a point directly above it that is 25% to the top ( or however much tint you want). Note the hex value of this new color. Do the same for the next three colors, trying for the same amount up from the original color.

Alternately, gather your 4 saturated colors together and draw a white rectangle over them and apply transparancy/difference and opacity 80% to the rectangle. You might have to try the other transparencies and opacity especially to get the right tints, or apply only opacity to the rectangle, adding white to your colors evenly to achieve the same tintedness.

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@Kristi927

There are a few ways I can think of, though none of them are super accurate and convenient in every case.


Option one is to use the sampler/color picker tool. Select it, and then set 'sample size' at the top to a large value that would cover about 1/4th of the image. By doing this, the sampler will take an average tint over a larger area, as opposed to a single pixel. If your image is too large, scale it down first.
Option two is to scale down the image to just a few pixels large. For example, if you'd use the image you provided, and you want 4 colors, scale the image down to 4 pixels high. This way, Photoshop finds the average colors for you when scaling.
Note: With the second option, it may help to set image interpolation (can be found in Photoshop's settings) to 'nearest neighbour'.


Alternatively, you can use Adobe Illustrator, should you have it.

Import the image you use, and look for 'image tracing'. Set image tracing to the best setting that suits your needs. In CS6 at least, there are presets for 3 or 6 colors, but if you open the image tracing panel you can set another desired amount of colors.

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