Python Create Image in color relative to integer

Question

I need to make an image, in Python, that looks like this but vertical and only green to red: http://www.google.co.uk/imgres?safe=off&espv=2&es_sm=91&biw=1280&bih=610&tbm=isch&tbnid=AuJytAtra5ARrM%3A&imgrefurl=http%3A%2F%2Fsvs.gsfc.nasa.gov%2Fgoto%3F4050&docid=cJwEIWqHngeBPM&imgurl=http%3A%2F%2Fsvs.gsfc.nasa.gov%2Fvis%2Fa000000%2Fa004000%2Fa004050%2Fcbar_scientists.png&w=1046&h=221&ei=9WMsU_TkHM-0hAfwyoDQBQ&zoom=1&ved=0CF4QhBwwAw&iact=rc&dur=194&page=1&start=0&ndsp=15

where green is 10 and red is 0. When it receives a number, it makes the bar colour up to the relevant point and b&w from there up. I then need Python to save this image to a location.

In this way, the image will represent how far away some thing is and show it in colour (green is far away - safe, red is close - danger) on the bar.

I know it's difficult to understand but how would I go about this?

Thanks!

Mark Setchell · Accepted Answer · 2014-03-21T17:04:32.883

0

I know nothing at all about Python, but I know a little about ImageMagick which is available here and has Python bindings.

If you run this ImageMagick command at the command line:

convert -size 100x500 gradient:#00ff00-#ff0000 full.jpg

you will get a 100x500 pixel image, called full.jpg, with a gradient from green to red that looks like this:

enter image description here

If you then run the following command:

convert full.jpg -gravity North -background gray -crop 100x250+0+0! -extent 100x500 crop.jpg

you will get a new image, called crop.jpg, that looks like this:

enter image description here

The 250 is the number that will control the amount that gets greyed out, so try varying that. So if your input number you mentioned is 1, maybe you would use 50 in place of 250 (because 1/10th of the 500px image height is 50px), if it is 2 maybe use 100 in place of 250...

And maybe that will help - maybe it won't!!!

edited Mar 21 '14 at 17:04

answered Mar 21 '14 at 16:58

Mark Setchell

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Thanks, I'll try this out and report back! – developius Mar 21 '14 at 18:44
Just a thought... if your number that controls it all is only an integer between 0..10, you could make the 11 images upfront and in advance, outside of Python, and then just select one of the 11 according to your number - no need to integrate any ImageMagick into your Python. – Mark Setchell Mar 21 '14 at 18:46
Good point... I'll try them both and see which works best :) thanks! – developius Mar 21 '14 at 20:31
Just one other thing, how can I create a completely gray one? For 0. – developius Apr 14 '14 at 17:21
A completely gray image? Like this... `convert -size 500x500 xc:gray gray.jpg` – Mark Setchell Apr 14 '14 at 18:14
To put the gray area at the top, change `-gravity North` to `-gravity South` – Mark Setchell Apr 14 '14 at 18:15

Python Create Image in color relative to integer

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