Introducing a Color Blind Filter

I was prompted by reading this conversation recently about color blind maps. I realized suddenly that we don’t support a way for our cartographers to easily design maps that would be easy to view by a color blind individual. Determined to change this, I quickly dashed off to my development batcave!

After some quick research I found a research paper on colour blindness. After quickly deducing that color should be spelled with out a u, I proceeded to throw together an algorithm. (Artem thinks it spelled with a u)

I emerged from the bat cave with some new code in Mapnik. Image filters for three types of color blindness.

• Protanopia (1% of males) – filter: color-blind-protanope
• Deuteranopia (1% of males) – filter: color-blind-deuteranope
• Tritanopia (less than 1% of males and females) – filter: color-blind-tritanope

So here are some maps with the color blind filters!

Original Wheat Paste

Protanopia Wheat Paste

Deuteranopia Wheat Paste

Tritanopia Wheat Paste

If all those maps look the same to you, you might be color blind.

Okay I lied, here are the real ones.

Original Wheat Paste

Protanopia Wheat Paste

Deuteranopia Wheat Paste

Tritanopia Wheat Paste

These image filters are now released in mapnik 3.0.3 and node mapnik 3.4.3!