[Image-SIG] grayscale image: find darkest pixel and delete lighter ones
Fredrik Lundh
fredrik at pythonware.com
Thu Apr 23 15:42:22 CEST 2009
On Thu, Apr 23, 2009 at 12:58 AM, Eduardo Ismael <eismb at hotmail.com> wrote:
> Hi!
> I wonder if it is possible to do something like the following with the
> Python Imaging library:
>
> for pixel in image:
> get how close to black it is
> register what would be the darkest shade found in the image
> delete pixels lighter than the darkest.
to get the darkest color in the image, use:
lo, hi = im.getextrema()
you can then create a lookup table that maps everything above lo plus
a small margin to white:
lut = [0]*256 # all black
for ix in range(lo + 10, 256):
lut[ix] = 255 # make everything from lo+10 to 255 white
and use the "point" method to translate the whole image:
im = im.point(lut)
tweak as necessary.
</F>
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