Banding problem

[Marpel]

I have an image of the sun shining through fog that has banding that emanates out from the sun in concentric circles (not overtly obvious until zoomed in). Unfortunately, the image is only 24 bit colour and the raw image has somehow disappeared so it can't be redone. I wish to composite this image with another, using the Hard Light blend mode, however, by doing so, the banding becomes very obvious and makes the resultant image useless.

I am wondering if there is some way the banding can be eliminated or reduced in the sun/fog image, prior to the compositing operation. The only thing I could think of was to apply some Gaussian blur to the banded image (as there is no detail to worry about), but, funny enough, the banding is still visible, regardless of the amount applied. I presume this is due to doing the operation to a 24 bit image??


Marv

[den]

Really need to see the images to be truly helpful but...
(1) you might try adding some Gaussian RGB noise to the image area with the bands, then Gaussian blur...
(2) perhaps use a higher Amount of Soft Light blending then what is used for the Hard Light blend...
(3) perhaps either Low Pass or High Pass blending would be more appropriate followed with a "S" contrast RGB Brightness Curve that is similar to Hard Light or Soft Light blending...
(4) perhaps PWP7 beta's Precise Gaussian blur would be helpful...

...den...

[Marpel]

Bit of a delay in getting back to this....

However, been playing somewhat with the suggestions offered by Den and have been able to mitigate the problem a bit but not completely eliminate. More experimenting is necessary (but attention currently being pulled away from PWP with getting ready for a driving trip to Denver). Anyway, just wanted to say thanks for your help, Den.

Marv

[tomczak]

One of Den's advises may work. Another is to convert image to 48bit, Gaussian blur it, but decrease highlight contrast (stretch it) before converting it back to 24bit. This allow the highlights to occupy greater range of values in 8bit and and thus reduce visible banding (smooth them).

[Charles2]

You might mask the "upper" or "lower" value bands with suitable blurring then do something.