scikit-image/scikit-image — pull request #1327 by endolith (2014-12-27 19:50:56+00:00)
Title: DOC: change colormap to gray

1. `jet` is generally discouraged as perceptually misleading: https://github.com/matplotlib/matplotlib/issues/875#issue-4616667
2. I think it's more clear when all 3 images use the same colormap, to show how an edge detector converts a solid block of brightness into bright lines on just the edges:

```
______
_____/ \_____ --> _____/\____/\_____
```