Re: transparent gifs...again (selecting)

At 12:39 AM 3/15/99, Luke Opperman wrote:
> If there were three things I would suggest everyone learn
> to really use in Photoshop, they would be the Path tool,
> Layers and Layer modes, and Masks/Alpha channels. (Well,
> maybe that could be more than three.)

That's very true -- the key requirement in pixel-based image editors is
selecting groups of pixels, and being able to reuse those selections. If
you're skilled in selecting groups, and constructing partial-selection
masks, and storing and manipulating those selection channels, then you've
got the major portion of the pixel-editing routine accomplished.


If I'm understanding this case correctly, though, then there may still be
problems... it may be too late to easily get a clean selection if:
> The gif image of a book is saved on a gray background... every gif
> gets some color of background, even when I save them as transparent.

If the book has a crisp, hard edge, then it's easy to use the Magic Wand to
select the background pixels. It's more likely it's blended to the
background, though... doing a Magic Wand selection would leave a little
grey halo around the book. You can try to reduce this effect by setting the
wand's tolerance, and feather, and perhaps some channel operations, but
this is a core difficulty in creating selection sets from flat pixel-based
images: What do you do with the blending pixels?


Lonna later wrote:
> I know I could have saved myself a lot of
> trouble if I would ALWAYS save my layers as a psd file.

That's true... if the book image was originally in its own layer, with a
clean feathered transparent edge, then you wouldn't have to reconstruct the
selection channel for subsequent manipulation. Even a scan, though, would
have to make that initial selection set at some time, though....


Summary: Flat pixel-based images don't have much organization within them,
and can make editing difficult. A key chore in pixel-based image editors is
creating and managing selection sets. The more modern tools tend to have
organizing structures built right into the image file.

jd

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