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06-07-2016, 04:27 PM   #16
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QuoteOriginally posted by Adam Quote
Do you see it when you develop the same file in PDCU?
Hi Adam,

My workflow is such that I do not use PDCU. I am still doing more testing with the PS. As soon as I get a chance later tonight, I will install PDCU and try to process the images again. If it solves the problem, then it is not a big deal, I will just incorporate PDCU into my workflow.

BTW, the non PS images are so good, I am having a hard time telling them apart.

---------- Post added 06-07-16 at 04:31 PM ----------

QuoteOriginally posted by stevebrot Quote
Sorry to be dumb, but what does this mean? Are you saying that you extracted the four DNG by some unknown process and are combining them manually in PS?


Steve
Steve,

I guess I got the two subjects mixed up and unnecessarily complicated the issue. There are four separate images shot to be stacked for better depth of field. At the same time, each individual image is also shot with Pixel Shift for better resolution. Hope this clarifies things.

06-07-2016, 04:33 PM   #17
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i have seen similar on occasion with non PS images on the K5. I am curious to know what causes it but had good results doubling the layer in post to remove it completely, fwiw. ymmv of course, since you are seeing this with PS.
06-07-2016, 04:37 PM   #18
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QuoteOriginally posted by house Quote
If it's only visible in photoshop it's probably an artefact of the image preview. Photoshop uses a lot of acceleration and tricks to speed up and make the view responsive. As long as the exported file is fine I wouldn't worry about it. I can only see it in your screendump. It's not visible in gimp on my computer.
That is a good point. It is possible. I am just trying to figure out where the problem originates from. As I mentioned earlier, I wanted to stay in 16-bit mode as long as possible. The PSD file in 16-bit shows this problem. As soon as I get out of 16-bit mode and go in to 8-bit, the problem goes away. I'll keep testing and also try PDCU to process the images into the 16-bit files. I'll see if the same problem shows up.
06-07-2016, 05:18 PM   #19
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QuoteOriginally posted by btnapa Quote
There are four separate images shot to be stacked for better depth of field. At the same time, each individual image is also shot with Pixel Shift for better resolution. Hope this clarifies things.
It does indeed! You are doing what MichaelErlewine is wanting to do, though he is having trouble integrating the K-1 into his flow.

BTW, I am curious as to whether this artifact shows up in a 16-bit PNG output. I agree with house that it likely has something to do with Photoshop. I am also curious as to what color space the four images were initially developed to and what space you are working in. Might the artifact have to do with failed gamut coercion?


Steve


Last edited by stevebrot; 06-07-2016 at 05:38 PM.
06-07-2016, 05:39 PM   #20
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QuoteOriginally posted by stevebrot Quote
It does indeed! You are doing what MichaelErlewine is wanting to do, though he is having trouble integrating the K-1 into his flow.

BTW, I am curious as to whether this artifact shows up in a 16-bit PNG output. I agree with house that it likely has something to do with Photoshop. I am also curious as to what color space the four images were initially developed to and what space you are working in. Might the artifact have to do with failed gamut coercion?


Steve
Steve, good point on the color space. I shot in sRGB but I think my output from Photoshop is ProRGB. I have to double check this issue. I guess I have some work ahead of me to figure this thing out.
06-07-2016, 06:03 PM   #21
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Check the color space, particularly if you have hardware acceleration enabled in PS.

I'm fighting with Adobe presently to get them to acknowledge and fix a bug that only shows up when you are using 16-bit ProPhoto RGB images with hardware acceleration enabled, in which case you see banding and artefacts on screen that disappear when you change color space or reduce color depth. Not sure why they'd be in the specific pattern you are seeing, but I have my suspicions that this could be why it is behaving the way it is.
06-07-2016, 06:59 PM   #22
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Known problem with Photoshop and Camera Raw?

Pixel shift resolution DNG files are not usable in PS with ACR at present. No release of ACR will work with PSR DNG files from K 1. Try PDCU 5.5.1.

An aside, PSR is not a stacking type process. See excellent review by PF available on this site.

RONC
06-07-2016, 06:59 PM   #23
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QuoteOriginally posted by paulster Quote
Check the color space, particularly if you have hardware acceleration enabled in PS.

I'm fighting with Adobe presently to get them to acknowledge and fix a bug that only shows up when you are using 16-bit ProPhoto RGB images with hardware acceleration enabled, in which case you see banding and artefacts on screen that disappear when you change color space or reduce color depth. Not sure why they'd be in the specific pattern you are seeing, but I have my suspicions that this could be why it is behaving the way it is.
Im wondering if it isn't some sort of quantization error.

06-07-2016, 08:42 PM   #24
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Did you come out of the camera with jpg files? If so pattern could easily be the normal stepping from jpg processing.
RONC
06-07-2016, 08:48 PM   #25
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QuoteOriginally posted by Wheatfield Quote
Im wondering if it isn't some sort of quantization error.
Well I think that the problem goes away at 8-bit because it just falls out of the quantifiable range. The problem definitely looks to be near the noise floor, which would be in the lower 8 bits. So quantization error would be an improvement in this case... something else is going on at 16 bit.

OP, can you explain your stacking? Are you building smart objects from the layers and setting a stacking mode? If not I'd recommend trying that with either median or mean mode and see if it still exists. It looks like a registration artifact from the algorithm locking on to fixed pattern noise.
06-07-2016, 11:38 PM   #26
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Interesting, raises a few questions though.

Are the images resized?
Can you see the pattern in each individual PS image?
If you can, is the pattern identical in each image?

Just trying to find out where the pattern comes from, is it from the sensor itself or created in the post process.
06-08-2016, 06:39 AM - 1 Like   #27
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QuoteOriginally posted by Nass Quote
That's starting to look a bit like the lattice problems I had with PS on K3ii, on the blue shot. But mine wasn't as regular, mainly just areas of lattice. I can't remember who or what site, but I was browsing recently and some respected photography reviewer site also saw the same thing (but also irregularly patterned like mine, not in a grid like yours). It's a known PS ?artifact (he had some fancy name for it, just can't remember sorry).
Just for the record, I've managed to look it up now - that fancy name for it was "checkerboarding", the site was diglloyd (don't have URL, it's a paywall site). I was doing a superresolution stack of 38 pixel-shifted exposures last year when Pentax made me a K3ii ambassador, but I couldn't make PS work for me because of artifacts like this. You can download the full resolution one via flickr - pic is https://www.flickr.com/photos/jingleslenobel/20545646184/in/dateposted-public/

Last edited by Nass; 05-08-2017 at 08:20 AM.
06-08-2016, 06:53 AM   #28
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What has the processing flow been?

Camera output? DNG, PEF, or jpg?
If not jpg, you used ACR to convert from raw-PSR to PSR.
PS to stack four PSR.
Anything else?
RONC
06-08-2016, 10:12 AM - 1 Like   #29
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QuoteOriginally posted by stevebrot Quote
It does indeed! You are doing what MichaelErlewine is wanting to do, though he is having trouble integrating the K-1 into his flow.

BTW, I am curious as to whether this artifact shows up in a 16-bit PNG output. I agree with house that it likely has something to do with Photoshop. I am also curious as to what color space the four images were initially developed to and what space you are working in. Might the artifact have to do with failed gamut coercion?


Steve
Steve, Thank you. You nailed it. It was a color space issue.

I was mistaken. Originally, I output the files from Photoshop in sRGB and that caused the problem. I just went back and set my output parameters from Photoshop to ProPhoto RGB. I then re-stacked and aligned the images. Surprise, surprise, the problem went away. I no longer see those funny patterns. I'll still do some more testing and let you all know.
06-08-2016, 10:20 AM   #30
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Glad to hear it, I was a little bit worried that there where a camera problem.
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