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Old Aug 20, 2006, 4:59 PM   #1
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Hi Mike,

with version v2007.120 Pro I get a very chequered jpg full screen preview. I don't remember seeing this rendering problem with the v2006 version. In any other full screen browser this pattern is not there. See attached crop from a full screen preview.

Cheers, Fons.

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Old Aug 21, 2006, 7:42 AM   #2
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This actually looks like a camera problem. The pattern displayed looks like the pattern I was getting on the defective Canon 5D camera that I tested. I returned the camera for a new one and never had another problem. What camera was used for this shot? The reason the pattern might show up more on a full screen shot is that the frequency of the pattern can align with the downsampling used to fit the photo to screen, making the pattern more noticeable.

Mike
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Old Aug 21, 2006, 7:45 AM   #3
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Hi Mike,

the photo was taken with a D2x. Like I said in PhotoMechanic, Bibble and Aperture I don't see these artifacts in full screen mode.

Cheers, Fons.

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Old Aug 21, 2006, 4:03 PM   #4
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I still believe the original has the artifacts and they are simply exagerated by the scaling method used to downsample the image to screen size. To know for sure, you'd have to post or send me the original file: not the raw but the JPEG/TIFF you were viewing in Qimage.

Mike
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Old Aug 22, 2006, 4:02 PM   #5
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Hi Mike,

the full jpg can be found here: ftp://root.cern.ch/pub/summer-2006-009.jpg
It was displayed on a 1600x1200 display in full screen with Qimage.

Cheers, Fons.
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Old Aug 22, 2006, 4:39 PM   #6
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Hi Mike,

looking at the file in firefox it turns out the same patterns it there too strongly. I noticed it also when browsing it with FastStone (less but still). I don't see it when rendered with PhotoMechanic and iView. Is this a downsampling artifact or is it something due to the way Bibble did process this file?

Cheers, Fons.

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Old Aug 23, 2006, 10:06 AM   #7
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The problem here is that the noise in that image is not random. It is repetative in nature (banding noise). This is the fault of the camera and not that of Bibble or any other raw tool. It is difficult to see the repeating pattern of the noise at 1:1 but when you shrink the image down to screen size, the noise patterns become more pronounced because the noise patterns start to align with the downsampling ratio and this causes a sort of "feedback" that enhances the pattern part of the noise.

Most tools use a fast form of downsampling to avoid display delays. To get rid of it on downsampling, you'd have to use antialiasing which can cause a delay. My best advice on this shot would be to use some noise filtering. It looks like the image could benefit from it to begin with, but particularly because the noise in that image actually is pattern noise and not random noise.

Mike
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Old Aug 23, 2006, 5:03 PM   #8
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Hi Mike,

thanks for the explanation. This is the first time I see this behaviour with my d2x, though.

Cheers, Fons.

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Old Aug 26, 2006, 6:53 PM   #9
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Ok, some more investigation. It has nothing to do with my D2x nor with Qimage. It has to do with Bibble. See the difference between:

ftp://root.cern.ch/pub/summer-2006-009.jpg (Bibble)
ftp://root.cern.ch/pub/summer-2006-009ap.jpg (Aperture)


Cheers, Fons.

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Old Aug 27, 2006, 3:16 PM   #10
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The Bibble version looks much sharper and also resolves more detail. The noise (as well as the detail) look a little mottled over in the Aperture version. It is possible that the Bibble parameters could be tweaked to eliminate the problem with either noise reduction or less sharpening. There's really no way to rule out the camera unless you post the raw file itself. It could be that the camera is at fault but that Aperture doesn't have enough resolving power to resolve the pattern.

Mike
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