Luminous Landscape Forum

Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: bcroslin on November 06, 2006, 07:42:22 pm

Title: Valeo Moire issue - need help!
Post by: bcroslin on November 06, 2006, 07:42:22 pm
I'm processing some images from a recent shoot and the subject's jacket has moire unlike anything I've ever seen. I've run the images through Leaf v10 with moire reduction at 100 and it's still there. Does anyone have a way to eliminate moire?

[attachment=1157:attachment]
Title: Valeo Moire issue - need help!
Post by: bcroslin on November 06, 2006, 08:24:35 pm
Just found this:

http://av.adobe.com/russellbrown/GoAwaySM.mov (http://av.adobe.com/russellbrown/GoAwaySM.mov)

first method works much better than the second IMO.
Title: Valeo Moire issue - need help!
Post by: Nick_T on November 06, 2006, 08:39:22 pm
Quote
I'm processing some images from a recent shoot and the subject's jacket has moire unlike anything I've ever seen. I've run the images through Leaf v10 with moire reduction at 100 and it's still there. Does anyone have a way to eliminate moire?

[attachment=1157:attachment]
[a href=\"index.php?act=findpost&pid=83902\"][{POST_SNAPBACK}][/a]

As a first quick step you can paint away the moire with a brush set to "colour" mode (and continuosly sampling "good" colour with the option key). Luminance moire is much tougher and that's where Russel Brown's channel replacement method works well.

Nick-T
Title: Valeo Moire issue - need help!
Post by: yaya on November 07, 2006, 02:09:38 am
Bob can you load a small crop of that mosaic file so we can run a few tests on it?

As Nick suggested the luminance moire is a tough one, best avoided by changing angle/ distance/ aperture/ focus while shooting (for next time).

The colour moire should be easily removed by the moire tool in LC10 or V8 which I'd like to test. If it doesn't work we'll send it to R&D to work on.

thanks, yair
Title: Valeo Moire issue - need help!
Post by: Morgan_Moore on November 07, 2006, 02:51:17 am
Pretty impressive

Would re-iterate that the best method is to stop it  at source

I beleive (simply) that moire occurs when the thread size is equal to a pixel size

If you spot it try shooting looser and cropping - changing the relative thread/pixel size

Less sharpening may help too and less DOF and a bit of camera shake (!)

SOftware fixes will always involve sofware 'inventing' data which will always look a bit wierd

Or a different jacket - people on  TV never wear herringbone (!!)

SMM
Title: Valeo Moire issue - need help!
Post by: AndrewDyer on November 07, 2006, 03:03:59 am
Quote
Just found this:

http://av.adobe.com/russellbrown/GoAwaySM.mov (http://av.adobe.com/russellbrown/GoAwaySM.mov)

first method works much better than the second IMO.
[a href=\"index.php?act=findpost&pid=83905\"][{POST_SNAPBACK}][/a]

Even though the second "Complex" method is much better than the first, it only works on objects that are relatively mono-colour. I would suggest strongly a less crude way of doing it by using a "Channel Mixer" adjustment layer (instead of pasting over the original image). Then you can Paint onto the adjustment layer with white where you want the effect to be present.

In Channel Mixer you can for instance replace the Blue channel with the Green channel by choosing the Blue channel from the top pop-down menu - draging the Blue slider to 0 and dragging the Green slider to 100. This can then be done to the Red channel if it needs it by just choosing the Red from the top pop-down menu and dragging the Red slider to 0 and the Green to 100.

The beauty of adjustment layers is that they never permanently change the pixels - you can just turn that layer off and it is back to the original. Where the adjustment layer is painted with White = 100% strength of the effect and Black = 0% (with percentages of Grey inbetween)

Careful painting of masks will let you isolate the change to specific areas - then once you have spent the effort making the mask you can always use the same mask applied to a Levels or Curves Adjustment layer to re-colour that area to what it should be.

I hope this makes sense to beginners of Photoshop.
Regards
Andrew
Title: Valeo Moire issue - need help!
Post by: bcroslin on November 07, 2006, 10:57:45 am
Yair,

I dropped the compressed .mos file on my ftp. You can grab it here:

http://www.bobcroslin.com/moire.html (http://www.bobcroslin.com/moire.html)
Title: Valeo Moire issue - need help!
Post by: bcroslin on November 09, 2006, 11:42:37 am
Just a follow-up should anyone end up in moire hell with a Leaf back:

Yair was nice enough to point out to me via email how the magical eraser tool works in LC v8 with HDR files. I'm amazed at how easy it was to eliminate moire with it.

Once again, another feather in LC v8's cap.