Re: true transparent backgrounds w/ Photoshop

Subject: Re: true transparent backgrounds w/ Photoshop
From: Elizabeth Ross <beth -at- vcubed -dot- com>
To: Amanda Baird <abaird -at- mail -dot- open-softech -dot- com>, TECHWR-L <techwr-l -at- lists -dot- raycomm -dot- com>
Date: Wed, 19 Apr 2000 10:03:15 -0400

Hi Amanda,

Here are a few thoughts:
> because the button is beveled and the text is shadowed, so the edges of the
> image are blended into the background, but I want a transparent background!!

This sounds like anti-aliasing, an effect used in Photoshop to blend images
into the background. Anti-aliasing and transparent GIFs do not like each
other. This is because the anti-aliasing occurs in the .psd file, when the
background colour is white (or grey or whatever you set it to as you said).
So Photoshop happily blends the colour of your image with the colour of your
background and creates a bunch of new colours that are on the gradient
between the two.

Then, you export as a GIF with a transparent background. Photoshop converts
your background colour (100% white or grey or whatever) to transparent. But
all those anti-aliased pixels are no longer 100% background colour, so they
stay the same and you end up with a whitish or greyish border around your
image.

So, to create a transparent GIF, turn off anti-aliasing.

Your other option is to use anti-aliasing sparingly and create several
versions with different background colours (light, dark, in-between). Then
convert to transparent GIFs and send the appropriate one off. More work, but
it might look better. Ideally, you would create a GIF with a background
colour the same as the target website, but ideal is not the same as
feasible.

Good luck!

--
Elizabeth Ross
Senior Technical Writer
V3 Semiconductor Corp.
beth -at- vcubed -dot- com
http://www.vcubed.com

Cogito cogito ergo cogito sum.


> From: "Amanda Baird" <abaird -at- mail -dot- open-softech -dot- com>
>
> I have a .psd layered file that I need to end up as a GIF with a transparent
> background. The image is a beveled WHITE button with a line of red text
> underneath the button like a caption. The button has text on it, but it's
> background is white and the beveled edges are basically shades of gray. The
> red "free-floating" caption text underneath is red with a gray shadow
> effect. So it's a white button with red text underneath. The red text has
> no background color.
>
> My company is going to be sending out this image as a gif for other
> companies to put on their websites, which may have white, black, gray,
> green, patterned, etc. backgrounds. But in Photoshop, I seem to HAVE to
> choose a "default" image transparency color, usually that color is gray, but
> then when viewed on say a white or a colored background, the image has a few
> pixels that are gray around it and the red text has gray too. If I choose
> white as the default transparency, I get a white border when viewed on a
> color other than white. When I export it and de-select the background
> myself, either I delete the white in the button (which I DON'T want) because
> the background color I am deleting is also white, OR if I fill in the
> background layer with a diff. color before I export it and then deselect the
> background color, there are always pixels left over of the background color,
> because the button is beveled and the text is shadowed, so the edges of the
> image are blended into the background, but I want a transparent background!!
>
> Is it possible to make a gif in Photoshop with a TRULY transparent
> background, one that will allow the image to "float" I guess over any
> background color?





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