How can I generate a random human-readable colour from a seed? C#

Question

Got a logfile, and it has all kinds of text in it. Currently it is just displayed as one colour, and each entry says something like:

Log from section 1: Some text here 
Log from section 125: Some text here 
Log from section 17: Some text here 
Log from section 1: Some text here 
Log from section 125: Some text here 
Log from section 1: Some text here 
Log from section 17: Some text here

Now the logfile is displayed in real time, and it would be nice to make the rows with the same section number the same colour. However there could be potentially quite a large range of numbers.

What I want to do is create a method that will take a number, and randomly generate a unique colour. The colour must be readable against a black background though, so #000000 is no good, nor is #101010 or anything too dark to read.

Ideally two similar numbers will not produce the same colour because in the above examples, the numbers 1 and 17 might be too similar, and some numbers might be in the 10,000 range.

Any ideas on this?

Answer 1

Yes. Just generate random numbers for a color in HSV color space and make sure V is above like 50% (so that it isn't too dark). Convert back to RGB as necessary. Pretty simple.

To make sure the colors aren't too similar... I don't know. Find out the range of possible numbers and split the color wheel evenly?

Answer 2

There are some fairly strict cognitive limits on how many different colors you can use. It would be better to carefully pre-select a range of colors. If you really need to differentiate more than a dozen or so distinct items, you'll need to use something else, like altering the background color as well.

Also, remember that 10% of the male (and therefore developer) population is color-blind, so unless it's just for your own benefit, I wouldn't rely too heavily on color.

A very interesting alternative technique can be found in TortoiseSVN's blame tool, which dynamically highlights lines with matching revisions as the mouse moves over the window.