Re: Transparent Color/Selective Area

At 12:30 AM 12/7/97 PST, Collin Lim wrote:
>Although I know the process to create a transparent GIF image on 
>Photoshop 4, I can't figure out how to do it selectively.  For example, 
>I have an image with white text surrounded by a blurred border.  Since 
>the textured backgound of the page is white, I've picked white as the 
>transparent color when exporting to GIF format.  Now, I've also made the 
>white text transparent, which I don't want.  Can someone shine a light 
>on me?
>
>Subject image is at http://www.angelfire.com/ca/zuniga/

The thing to remember about Gif is that it's an /indexed/ file format.
Each colour is defined, and with a transparency in gif89a, you're basically
just flagging one of the indexes as 'transparent'.  this is sort of like
apaint by numbers-- whenever the rendering software encounters that 'index'
or colour, it will let the background show through.  the way to do this is
either make sure that the area you want as transparent is not using the
same index as anything else (two indexes of white, in this case) and/or
that the colours are similar, but not exactly the same.

I do quick changes to the index using Lview Pro, not photoshop, btw.

Green

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