Pixel shift with pixel artefacts

Dericali · 07-18-2018, 05:51 AM

Recently I did some photography of paintings using the pixel shift function on the K1 (using the 50mm macro lens). Camera was on a tripod, SR was off.

I have noticed what look to be some distortions at a pixel level in the areas of dark paint, which show as a single bright pixel. I took non-PS photos at the same time, so in some cases I can see some kind of mark or colour in the non-PS photos, in others I see nothing.

I'm viewing these at 4:1- 8:1 in LR, but if you know where to look you will see them at 1:1 on my 27" monitor. I'm concerned because this would undercut using PS for certain kinds of photography like archiving.

I'm wondering if anyone has noticed anything similar or whether this could be caused by some other phenomenon such as dead pixels in my camera, dirt on the sensor? Does this always happen with PS when trying to photograph specks of colour smaller than 1 pixel? Should I look at developing PS photos in SilkyPix or alternate avenues than LR?

Raw files here:

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Attached Images

photoptimist · 07-18-2018, 06:29 AM

These are defective pixels. The easiest solution is to run the "Pixel Mapping" function in #4 Wrench menu before you do a run of archival images.

house · 07-18-2018, 07:13 AM

Do you know for certain that there are no bright specks on the painting? Pixelshift picks up on single-pixel level detail. I've had examples where I thought there was artifacts but realised it was actual detail. Contrast at pixel level can get very high.

Roadrunnerdeluxe · 07-18-2018, 09:42 AM

Originally posted by Dericali

Recently I did some photography of paintings using the pixel shift function on the K1 (using the 50mm macro lens). Camera was on a tripod, SR was off.

I have noticed what look to be some distortions at a pixel level in the areas of dark paint, which show as a single bright pixel. I took non-PS photos at the same time, so in some cases I can see some kind of mark or colour in the non-PS photos, in others I see nothing.

I'm viewing these at 4:1- 8:1 in LR, but if you know where to look you will see them at 1:1 on my 27" monitor. I'm concerned because this would undercut using PS for certain kinds of photography like archiving.

I'm wondering if anyone has noticed anything similar or whether this could be caused by some other phenomenon such as dead pixels in my camera, dirt on the sensor? Does this always happen with PS when trying to photograph specks of colour smaller than 1 pixel? Should I look at developing PS photos in SilkyPix or alternate avenues than LR?

Raw files here:

Update your browser to use Google Drive - Google Drive Help

I have had the exact same problem. Night-pixel shift exposures were littered with very bright red, green and blue random square artifacts. Photoptimist is correct: pixel mapping fixed the issue for me.

Dericali · 07-18-2018, 12:57 PM

Originally posted by photoptimist

These are defective pixels. The easiest solution is to run the "Pixel Mapping" function in #4 Wrench menu before you do a run of archival images.

Okay that's great to know. Thanks

07-18-2018, 05:51 AM	#1
Dericali Senior Member Join Date: Jul 2016 Location: Berlin Posts: 298	Pixel shift with pixel artefacts Recently I did some photography of paintings using the pixel shift function on the K1 (using the 50mm macro lens). Camera was on a tripod, SR was off. I have noticed what look to be some distortions at a pixel level in the areas of dark paint, which show as a single bright pixel. I took non-PS photos at the same time, so in some cases I can see some kind of mark or colour in the non-PS photos, in others I see nothing. I'm viewing these at 4:1- 8:1 in LR, but if you know where to look you will see them at 1:1 on my 27" monitor. I'm concerned because this would undercut using PS for certain kinds of photography like archiving. I'm wondering if anyone has noticed anything similar or whether this could be caused by some other phenomenon such as dead pixels in my camera, dirt on the sensor? Does this always happen with PS when trying to photograph specks of colour smaller than 1 pixel? Should I look at developing PS photos in SilkyPix or alternate avenues than LR? Raw files here: Update your browser to use Google Drive - Google Drive Help Attached Images

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07-18-2018, 06:29 AM	#2
photoptimist Pentaxian Join Date: Jul 2016 Photos: Albums Posts: 5,121	These are defective pixels. The easiest solution is to run the "Pixel Mapping" function in #4 Wrench menu before you do a run of archival images.

07-18-2018, 07:13 AM	#3
house Pentaxian Join Date: May 2015 Photos: Albums Posts: 3,306	Do you know for certain that there are no bright specks on the painting? Pixelshift picks up on single-pixel level detail. I've had examples where I thought there was artifacts but realised it was actual detail. Contrast at pixel level can get very high.

07-18-2018, 09:42 AM	#4
Roadrunnerdeluxe Forum Member Join Date: May 2013 Posts: 97	Originally posted by Dericali Recently I did some photography of paintings using the pixel shift function on the K1 (using the 50mm macro lens). Camera was on a tripod, SR was off. I have noticed what look to be some distortions at a pixel level in the areas of dark paint, which show as a single bright pixel. I took non-PS photos at the same time, so in some cases I can see some kind of mark or colour in the non-PS photos, in others I see nothing. I'm viewing these at 4:1- 8:1 in LR, but if you know where to look you will see them at 1:1 on my 27" monitor. I'm concerned because this would undercut using PS for certain kinds of photography like archiving. I'm wondering if anyone has noticed anything similar or whether this could be caused by some other phenomenon such as dead pixels in my camera, dirt on the sensor? Does this always happen with PS when trying to photograph specks of colour smaller than 1 pixel? Should I look at developing PS photos in SilkyPix or alternate avenues than LR? Raw files here: Update your browser to use Google Drive - Google Drive Help I have had the exact same problem. Night-pixel shift exposures were littered with very bright red, green and blue random square artifacts. Photoptimist is correct: pixel mapping fixed the issue for me.

07-18-2018, 12:57 PM	#5
Dericali Senior Member Join Date: Jul 2016 Location: Berlin Posts: 298 Original Poster	Originally posted by photoptimist These are defective pixels. The easiest solution is to run the "Pixel Mapping" function in #4 Wrench menu before you do a run of archival images. Okay that's great to know. Thanks

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