Re: [PyOpenGL-Users] False color images

[Mike C. F. <mcf...@vr...>]

On 12-02-10 05:33 PM, Derakon wrote:
> I have a program that displays monochrome camera images, obtained as
> Numpy arrays of 16-bit integer pixel brightnesses. I'd like to have a
> false-color mode that displays low values as blue and high values as
> red, to get some extra contrast and make it easier to tell where the
> brightest pixels in the image are. I did some searching around and
> about all I can find is some discussion on using color-index mode,
> with concern that it's really meant for palettized sprites and isn't
> really recommended these days. Is that accurate?
>
> Presumably this task has been done before; what's the recommended way
> to do false color? Especially, I want to be able to rescale what value
> is considered the darkest and what the brightest on the fly -- for
> example, if I get an image where the distance between darkest and
> brightest pixel is only 1000 (~10 bits) then I don't want to be
> scaling things as if the brightest pixel is 2^16-1 and the darkest is
> 0.
>
> Any advice would be recommended. Thanks.
Why not simply do the scaling in the numpy array?  That is, to increase 
the dynamic range array = array - min( array); array = array * 
(2**16-1/max(array)) (sorry if I messed up the numbers there, hopefully 
you get the idea, I have a two year old yelling in my ear at the 
moment).  To do the false-color, you can use a shader, or just duplicate 
the data into RGB channels. Indexed-color mode is pretty poorly 
tested/supported these days; it may work, but I can't say I've used it 
in the last decade or so.

HTH,
Mike

-- 
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   Mike C. Fletcher
   Designer, VR Plumber, Coder
   http://www.vrplumber.com
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