Banding in Composited Gradients

[stupid]

Hi, all.

A question regarding "banding" when compositing gradients.

I have some (approx. 800) full-size crops (jpegs) of cloud formations. I need to apply a gradient similar to a weak, rectangular vignette to perform what you might call the digital equivalent of edge-burning in order to define the edges against a background. I can make the gradient easily enough but no matter how smooth it is I get vague(ish) banding when it's composited onto the destination. Obviously with 8-bit imagery this is always going to tend towards the problematic. The usual remedy is to add noise to the gradient in addition to the default dithering; but because of the smooth nature of the images - sky/cloud - the noise is noticeable. Just hoping vaguely that someone might have "been there; done that" and discovered/developed an alternative method.

Thanks.


Jo

[fmw42]

can you post a link and example to your problem and your command line used for processing?

Also what version of IM are you using and on what platform?