Automatic Color Palette Creation

Fractint MAP format palette files

Going back 30 years, Fractint was a fractal generation program for DOS based systems. For its time it was the fractal program of choice for enthusiasts.

Fractint used a simple text format for its color palettes. These *.MAP files were text files with each color’s RGB values separated by spaces each on a new line. So, for example if you wanted the first color in your palette to be blue the first line would be “0 0 255”.

When I first started creating Visions of Chaos I adopted the format. The most common map files had 256 colors (you could have palettes with other color counts but I only use 256 color palettes).

The rest of this post covers the palette creation methods that have been included with Visions of Chaos. Although I use these methods specifically to create 256 color MAP files the principles could be applied to any number of colors for different sized palettes.

If you are just looking for a Fractint color palette collection, scroll down to the end of this post and grab the archive provided.

Smoothly blending colors

This is probably the first and most obvious method to use. Take a small number of base colors (I allow up to 16) and blend them into a palette.

How you get the colors to blend can be;

1. User selects them from the standard color picker dialog.
2. User can use eye dropper functionality to pick them out of a photo.
3. Set them at random.
4. Use the color wheel. Allows selection of complmentary colors, tetrads, and other color theory based colors.

5. Extract colors from an image. See this previous blog post explaining how that works.

Once you have the colors there are numerous ways you can blend them;

1. Smooth blend. Smoothly interpolate the colors.

2. Fade out blend. Fade each of the colors to black.

3. Fade in blend. Fade each of the colors from black.

4. Neon blend. Fade from black to the colors then back to black.

5. Stripe blend. Alternate each color for the duration of the palette.

Using curves to create palettes

The idea here is to use various mathematical functions to generate curves for the RGB components of the palette. The following is a list of the various methods I use so far.

Sine. Each RGB color component is its own sine wave. Randomize the wave amplitude, frequency and period.

Multiple Sine. Add multiple sine waves together for each RGB component and then scale down to between 0 and 255.

IQ. Idea from Inigo Quilez.

Perlin. Use repeating noise loops as in this coding train video. Map the resulting noise values to each RGB channel. Using a looping noise function is best because it means the palette wraps around smoothly and using it for fractal zooms does not show a sharp break when the palette ends and restarts. I have only implemented this method over the last few days (at the time of writing this post), but so far it gives some really unique color palettes.

Here are some examples palettes created using Perlin noise. Click to see the full sized image.

Simplex. Same as Perlin, but uses Simplex noise.

Simplex + Perlin. Create each RGB value by adding Simplex noise to Perlin noise.

Here are some examples of Simplex and Simplex + Perlin palettes. Click for full size.

Multiple Perlin – Add/subtract multiple Perlin Noise curves into RGB amounts.

Random Walk. Random curve for each RGB component between index 0 and 127. Reverse for the rest of the palette. Each step the RGB is changed by +random(5)-2 to randomly go up and/or down.

Terrain Fault. Take 2 random points between 0 and 255. Between the points randomly raise or lower by a small amount. Repeat this a number of times.

HSL to RGB. Random HSL curves converted to RGB.

RGB. Random curves for each RGB component. Use various easing functions to tween curve control points.

YUV to RGB. Random YUV curves converted to RGB.

Combine palettes. Take 2 previously created palettes and combine their RGB components by addition, subtraction or multiplication.

Multiple RGB. Combine multiple RGB curves.

Multiple YUV to RGB. Combine multiple YUV to RGB curves.

Modify an existing palette

Once you have palette files, you can also use various techniques to modify them;

1. Increase or decrease the individual RGB channel amounts
2. Brightness
3. Contrast
4. Increase or decrease the individual YUV channel amounts
5. Wrap. Take the existing palette, halve it, then add the flipped half to itself. This is useful when you want a non repeating palette to wrap around.

6. Double. If you have a palette that is too smooth/sparse for the current fractal image, doubling can add more lines/gradients to the palette.

7. Blur. Just like a blur function in image processing. Averages out the palette values with neighbor colors.
8. Sharpen. Just like a sharpen function in image processing.
9. Shift RGB. R->G,G->B,B->R.

10. Invert. R=255-R, G=255-G, B=255-B.
11. Reverse. Flip the order of the palette colors.
12. Histogram equalize palette. Like the auto-levels in Photoshop. My method tends to make the results slightly too bright. Needs fixing when I get a chance.

13. Matrix multiplication. Take a 3×3 matrix and multiply the 1×3 RGB components by the matrix to get new RGB amounts.

Any other ideas?

If you know of any other ways to generate palettes, or have an idea for ways to create new unique color palettes, let me know.

Availability

The color palette editor shown in this post is included with Visions of Chaos.

Just give me the palettes!

If you are using another program that uses Fractint palette files you can download the 3371 color palettes I include with Visions of Chaos here. Some created by me, others found on various Internet sites over the years, some converted from gradient packs. No copyright on them so do with them as you wish.

If you do have any other sets of MAP palettes you would like to share, send me an email. You can never have enough colors when creating fractal images.

Jason.