Irregular interval in Matlab Colormap

Question

I am plotting values using the "patch" function in Matlab, where data stored in a vector define the color of the patches.

My data range from 0 to 5, but most of the data are bunched around 0.5 and 4.5. If I set the limits of the colormap [0-1] I lose the detail in the higher values and if I set the range [0-5], I lose information for the lower values in my plot.

I am trying to create my own colormap, defining the colours in three RGB columns, but don't understand how the colours are distributed. How do I define the spacing, in order to get more definition in lower and higher values? Is there an other way around?

Many different ways to do it programmatically, but if it's only for one time use, you could use the Matlab built-in [`colormapeditor`](http://uk.mathworks.com/help/matlab/ref/colormapeditor.html) — Hoki, Jul 02 '15 at 13:27
I'd say you need a [**non-linear colormap**](http://stackoverflow.com/a/20629872/2605073). — Robert Seifert, Jul 02 '15 at 14:46
This might help you: http://stackoverflow.com/questions/17230837/how-to-create-a-custom-colormap-programatically/17232355#17232355 just set your colours at the `x` points relevant to you i.e. something like `x = [0 0.5 4.5 5]`. This is essentially what I think [Naveh's answer](http://stackoverflow.com/a/31185885/1011724) is suggesting. — Dan, Jul 02 '15 at 14:48

score 1 · Accepted Answer · answered Jul 02 '15 at 13:25

From the colormap documentation:

To create a custom colormap, specify map as a three-column matrix of RGB triplets where each row defines one color. An RGB triplet is a three-element row vector whose elements specify the intensities of the red, green, and blue components of the color. The intensities must be in the range [0,1]. For example, this matrix defines a colormap containing five colors.

map = [0.2, 0.1, 0.5
    0.1, 0.5, 0.8
    0.2, 0.7, 0.6
    0.8, 0.7, 0.3
    0.9, 1, 0];

What I would do is take your chosen colormap and interpolate more values in the middle of it, so that most variation is pushed to the lower and upper values.

Irregular interval in Matlab Colormap

1 Answers1