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08-27-2015, 08:32 PM   #1
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Testing K3 II pixel shift with dcraw

Hello All,
Not sure if this the correct place for this little ditty, but as it relates to K3 II I'll start here.
I came across a version of dcraw, by Tom Vijlbrief, which incorporates an ability to convert a pixel shift RAW.
I build this on Linux and it seems to be working, it reports the version as "9.26 Pentax PS v0.65", which is correct.
I have done a few test shots, both normal RAW (DNG) and with pixel shift, but it isn't clear to me that the PS version of dcraw is really doing what it should.
If I run dcraw with a pixel shift image, it reports, as I would expect it to, as follows...

[terry@localhost 3rd]$ dcraw -v -w -4 -T IMGP0343.DNG
Loading Pentax K-3 II image from IMGP0343.DNG ...
Load PS images...
AHD interpolation...
Merge PS images...
PS artifacts: 0
Scaling with darkness 0, saturation 16125, and
multipliers 2.195312 1.000000 1.476562 1.000000
Converting to sRGB colorspace...
Writing data to IMGP0343.tiff ...

but comparing this tiff with the output from Ricoh's "Digital Camera Utility 5" and a tiff converted from a normal shot (no pixel shift) the latter looks identical to the result from dcraw whilst the tiff from DCU5 is clearly higher quality.

Is there any here that is using Tom's modified version of dcraw, and are you getting expected results?

Cheers,
Terry

08-27-2015, 11:28 PM   #2
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A quick follow-up for those interested.
I have made contact with Tom, and given the printed messages Tom thinks it is all OK.
His advice is that TIFF from dcraw need a lot of post processing, like sharpening, local contrast etc to get an image like out-of-camera or from DCU.

Cheers,
Terry
08-30-2015, 01:35 PM   #3
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QuoteOriginally posted by tduell Quote
A quick follow-up for those interested.
I have made contact with Tom, and given the printed messages Tom thinks it is all OK.
His advice is that TIFF from dcraw need a lot of post processing, like sharpening, local contrast etc to get an image like out-of-camera or from DCU.

Cheers,
Terry
Without reference to the K-3 II pixel-shift thing, I can confirm the dcraw output needs some TLC but when you end up doing so, it blows every other raw converter out of the water. It does take a fair amount of twiddling and tweaking and it's far from wysiwyg which tends to put people off. I use UFRaw which is basically dcraw with a GUI and some extra bits and pieces thrown in (color curves, saturation, geometry, lensfun library corrections etc.). Same applies there.
08-30-2015, 11:38 PM   #4
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QuoteOriginally posted by newmikey Quote
Without reference to the K-3 II pixel-shift thing, I can confirm the dcraw output needs some TLC but when you end up doing so, it blows every other raw converter out of the water. It does take a fair amount of twiddling and tweaking and it's far from wysiwyg which tends to put people off. I use UFRaw which is basically dcraw with a GUI and some extra bits and pieces thrown in (color curves, saturation, geometry, lensfun library corrections etc.). Same applies there.
I did look at UFRaw some time back, but I am guessing that it doesn't use a version of dcraw with Tom's PS patch, hence I expect it will only use the first of the 4 images in a PS raw.

Cheers,
Terry

08-31-2015, 01:51 AM   #5
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QuoteOriginally posted by tduell Quote
I did look at UFRaw some time back, but I am guessing that it doesn't use a version of dcraw with Tom's PS patch, hence I expect it will only use the first of the 4 images in a PS raw.

Cheers,
Terry
I wonder if a short note to UFRaw's developer/maintainer, Udi Fuchs, would help. Not having a K-3 II, I'd leave that up to you though.
08-31-2015, 10:59 PM   #6
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QuoteOriginally posted by newmikey Quote
I wonder if a short note to UFRaw's developer/maintainer, Udi Fuchs, would help. Not having a K-3 II, I'd leave that up to you though.
That's probably a bit premature as although Tom has submitted his patch to David Coffin, as far as I know DC has yet to accept/incorporate the patch into dcraw and release an updated version.
If anyone needs this ability, my advice would be to get the source of dcraw, and also get Tom's dcrawps.c, and do a local build as dcrawps...or, if you use Windows Tom has a 32bit .exe available. Search for dcrawps should turn it up.

Cheers,
Terry
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