Hi, this might be a way to achieve this: 1. create jet colormap 2. convert color map to HSV-space and sort according to hue 3. use sorted jet color map as lookup table / colormap for image I hope this helps. Johannes Schönberger Am 23.11.2012 um 05:08 schrieb Guillaume CALMETTES <guillaume.calmettes@gmail.com>:

Hello,

I am looking to convert an image saved with the jet colormap to grayscale. I tried to play a bit with the color module of skimage, but for the moment I couldn't manage to to map the jet colormap to linearly go from dark to light shades of gray. The main problem when applying a basic rgb2gray conversion is that the min/max values (blue and red) converge to the same dark value in the grayscale image, while the mid-range values (yellow/green) become the brightest.

Do someone has any trick to convert a "jet image" to grayscale?

Thanks a lot

Guillaume

PS: I have attached a picture as an example if you're willing to play with it ;)

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<im2.tif><cmap.png>

Hi Guillaume On Thu, Nov 22, 2012 at 8:08 PM, Guillaume CALMETTES <guillaume.calmettes@gmail.com> wrote:

Do someone has any trick to convert a "jet image" to grayscale?

Here's a snippet that does it by brute force lookup: https://gist.github.com/4146612 Hope that helps! Stéfan