[Image-SIG] Colorize Image

[Espen Moe-Nilssen]

Thanks a lot. I thought there had to be one, but I never found it.
This will come in very handy

Espen,

>There is a function for this. from the handbook:
>ImageOps.colorize(image, black, white) => image
>
>Colorize grayscale image. The black and white arguments should be RGB
>tuples or color names; this function calculates a colour wedge mapping
>all black pixels in the source image to the first colour, and all
>white pixels to the second colour.
>
>call it with your color for black and white for white, it accepts all
>"standard" color specifications, such as "#ff2253" or (255, 0, 0).
>
>On Thu, Feb 11, 2010 at 3:50 AM,  <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
>> _______________________________________________
>> Image-SIG maillist  -  Image-SIG at python.org
>> http://mail.python.org/mailman/listinfo/image-sig
>>


-- 
Espen Moe-Nilssen
Grieg Medialog AS