Re: Changing colors of a gif image

Knute Johnson <>
Tue, 25 Sep 2007 15:44:03 -0700
Todd wrote:

Hello again,

I got the .gif file that I have to be transparent in the correct
locations. Now, I would like to change the colors of the remaining
pixels based upon an input color.

I have looked at ConvolveColorOp, but don't understand how to define a
ColorSpace to convert, say black to blue. Maybe I am missing
something quite simple, but ...

I have looked at RescaleOp, but get an error stating "Rescaling cannot
be performed on an indexed image." I was probably on the wrong path
here anyway - I set all the scales to zero and then used the RGB
values of the input color as the offsets, me thinks that this will
give a single colored block.

I have spent way too many hours trying to decipher the Java tutorials,
which are surprisingly sparse when it comes to ConvolveColorOp, so I
am asking for help from you guys.

Any thoughts on how to change pixel colors within a .gif file are

There is no ConvolveColorOp. There is a ConvolveOp and a
ColorConvertOp. Neither of which are particularly suited to what you
want to do.

Load your GIF image into a BufferedImage object and modify the pixels
directly and then either display it or write it to permanent storage.


Knute Johnson
email s/nospam/knute/

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