Separating layers in GIMP for a "slideshow" .gif?

[ssshakedown]

Alright, so I'm trying to make a neat little .gif that flips through a few images in a loop. So, I downloaded the images, and put them each as their own layer. Obviously, I ended up with this:

No good, the images all build on each other, rather than showing separately.

So, the forum I was planning on using this as an avatar for having a white background, I separated each image with a plain white layer. This is what I got:
http://img5.imageshack.us/my.php?ima...ionavatar2.gif*
I linked it because this page displays the problem I encountered: the whites are not the same, so you can differentiate the avatar from the background. Now, I said to myself, "Easy peasy, I have the wrong white," so I took a screenshot of the forum and took that white with the little color picker thing. Lo and behold, I indeed had the right shade of white, it just would not match up.

So my question to you guys is: how can I separate the layers so that I get results like the second image I posted, but without trying to use blank white layers (I tried this with a different forum I use with a blue background, and again, the colors wouldn't match, even with the color picker). Is there a way I can "separate" each layer so that they show individually in the .gif?

If not, what's the problem with my colors? When I screenshot the forum to take the color with the color picker, is THAT image using the incorrect color? Or do I have the right color, but GIMP won't pull the right one with the tool? Or do I have the right color until I host the image on Imageshack or Photobucket and THAT messes it up?

[Dave Humphries]

The problem is the GIF file format supports a lot less colours than does a website or a jpg.
I might be wrong, but 256 for GIF and 65,536 for jpg from memory.

Sorry, that's all I have time for right now, off to work.

Cheers,

[ssshakedown]

The problem is the GIF file format supports a lot less colours than does a website or a jpg.
I might be wrong, but 256 for GIF and 65,536 for jpg from memory.

Sorry, that's all I have time for right now, off to work.

Cheers,

Ok, that makes sense. So is there a way I can "separate" them?

[Dave Humphries]

Sorry, but I have zero experience with GIFs and barely understand that bit of the question.

As GIFs aren't used for photography, and no-one else here has offered a solution, I'm thinking you'll need to find a place where people have more experience of them.

Sorry I can't help personally, but that's the best advice I can offer as I/we've been unable to find an answer for you.

Good luck,

[dendrophile]

Guys,

All that I can think of is that the GIMP is taking each of your grabs in turn and converting them into the 8-bit format used by GIF. Although each image has the same background colour when this process starts, the technique used to do the quantisation to 8 bits does not guarantee to preserve any colour. I have two suggestions, one is to look and see when the GIMP can be told to create one 256-colour palette to be used by all 5 of your images rather than one per image, or, if the GIMP cannot do that, create a single image and cut/paste your artwork into that. Then convert to 256-colour, and hopefully you'll end up with a single image with a colour palette that works. Finally, recreate your 5 images, keeping them as 8-bit, and the GIMP should now not have to do the colour conversion.

Sorry to add that late, and after Dave has apologized that CiC can't help... Not being a GIF expert, I was kind of hoping that someone with more knowledge might chip in.

Best,
Graham