Weird artifacts in CS3 stitches

[Peter McLennan]

They arise when you convert a Photomerge stitch to monochrome using the BW converter in CS3 and are found in dark, smooth sky areas along the stitch boundaries.

These artifacts look similar to banding, but do not appear to be density-related contours.  They're radiating patterns sometimes originating at the image edge and covering a fairly larg area.  They're almost impossible to hide.  

I flatten the original stitch so I can use Warp to adjust the image boundaries, then use BW convert on the warped image.  They appear with BW presets or manual adjustments  and converting the flattened image to 16 bit before converting has no effect.

Anyone else seen these?  Any ideas on how to avoid 'em?

http://www.flickr.com/photos/21207680@N00/491658004/

[Richowens]

Peter,
 
 Have you tried converting to monochrome before stitching?

Rich

[Peter McLennan]

Peter,
 
 Have you tried converting to monochrome before stitching?

Rich
[a href=\"index.php?act=findpost&pid=116683\"][{POST_SNAPBACK}][/a]

No, not until you suggested it.   Good idea.  Unfortunately, I still see them.  

Converting to BW first presents workflow and stitching difficulties, too.  It's more work to convert them first since the same BW adjustments have to be made twice, rather than once on the finished stitch.  

Also, once you make any changes to a recently-imported-from-CR image, CS3 insists you save the images before it'll stitch them.  If you just RAW convert them and stitch right away, you're saved this step.

thanks for the suggestion, Rich.

[Richowens]

Your welcome,

 It was just a thought. I don't have CS3 yet so I'm not familiar with any of  its quirks.
 
 
 Rich

[Peter McLennan]

I can see these artifacts in colour stitches, too.  It needs some pretty substantial curve moves to reveal them, but they're there, lurking.

Once the image is converted to monochrome, much less image adjustment is required to reveal the problem.  Here's a simple example:

http://www.flickr.com/photo_zoom.gne?id=492058390&size=l

The upper center of the dark sky areas clearly shows the problem.

After stitching, using the convert to BW tool I darkened the sky from about 128  to 40 with the cyan and blue sliders, not an outrageous move, but a pretty big one - one that adds considerable drama to the image.  Unfortunately, it also renders the image unusable.

I'm extremely disappointed with this and unless I can discover a workaround, to me PSCS3 is useless for BW images that are created from Photomerge stitches.