Image shadow looks rippled not smooth

[RigelBlueStar]

I'm using a gif image on my site that is a picture of the earth with a gray shadow casting below it as though it were sitting on a flat surface. When I F12 it from Fireworks or insert it on a page in Dreamweave the image looks fine except the shadow looks rippled instead of a nice and even gradient.

I can't do without this image so I need to correct the problem. Can anyone help me?

[jtara]

The shadow edges are probably "dithered" to the original color. In other words, pixels of "in between" colors are used to smooth the transition of the edges to the background. This in between pixels are inserted in both the background and the object (shadow).

If you want to use a new background color, the RIGHT way to do it is to go back to the original, undithered image, and dither it against the new background.

Otherwise, perhaps those more familiar with graphics programs can suggest how to remove the dithering. I gather it's not easy, and not sure it's even possible to have a fully automated solution. You need a keen eye and the patience to work with individual pixels.

Of course, GIF is not great format for an image with soft features like a shadow - you should probably be using JPEG. Unless, of course, you are using transparency (you didn't say). Is transparency the reason you are using GIF?

If so, your original image may not be dithered. But it isn't going to look good against any background without dithering. Kinda defeats the purpose of transparency...

Rather than using transparency, the only way to make this look good is to dither it against a background the same color as your page background. Then you don't need transparency.

[RigelBlueStar]

Thanks for the info. I'm one of those "figure it out the hard way as you go" type. After I submittem my question I went in and converted to a GIF and increased the quality. It looks fine now. I purchased the pic of the Internet and it came as a GIF. I should have changed it first.

Thank you for your time and help.

Best regards,
RigelBlueStar~