[Image-SIG] How to apply a threshold value to the image

[export at hope.cz]

Can anyone give me an example how to apply a threshold value to an image?

(everything above a certain brightness level becomes white, and everything below the
 level becomes black.)

I was told I should use 256-item mapping table and pass it to the "point" method.

But how should the 256-item mapping table  look like, if the threshold is 18( found from the histogram)


Thank you for any hint.
L.


> export at hope.cz wrote:
> 
> > I would need to apply a threshold value to the image, where everything 
> > above a certain brightness level becomes white, and everything below the 
> > level becomes black.
> > How can I do that with PIL?
> 
> create a 256-item mapping table and pass it to the "point" method.
> 
> </F>
> 
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