[Image-SIG] Colorize Image

[Stani]

How about using ImageOps.colorize ;-) ?

On Thu, Feb 11, 2010 at 12:50 PM,  <jcupitt at gmail.com> wrote:
> On 10 February 2010 11:01, Espen Moe-Nilssen <espen at medialog.no> wrote:
>> We are making an open source project, http://plone.org/products/subskins
>> I have been trying over and over again to find a way to let PIL colorize an
>> image.
>> It should work like this:
>> 1) I have a greyscale image
>> 2) A color is selected, for example "#123456"
>> 3) The image is colorized in this way:
>>     Whatever was white is still white
>>     Whatever was black (100%) is now "#123456"
>>     Whaterver was grey (50%) is now 50% of "#123456"
>> I have tried a lot of different approaches, but the colors always come out
>> too dark. Is there a way to do this ?
>
> You need to split the image into luminance (your greyscale image) and
> colour (the constant colour you want to apply).
>
> If you imagine the RGB space as a cube, the neutral axis (all the grey
> colours) is a straight line from (0, 0, 0) to (255, 255, 255). What
> you want to do is translate that line (ie. keep the angle of the thing
> the same, just translate the whole line up/down/left/right/fwd/back)
> so that it passes through #123456 instead. Any bits that go over 255
> or under 0 need to be clipped.
>
> This is easy in CIELAB space, but still OK in RGB.
>
> John
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