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Forum: Photographic Technique
09-25-2017, 04:22 AM
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In light of what I stated in my last post, so many comment that the Pixel Shift process is for pixel peepers and buys one nothing once it is sub-sampled for display, I would like to point out that because of the coherency gained from the Pixel Shift process it also enhances later processes such as sharpening. We should always try to keep in mind what benefits are gained much later in processing when we choose both which processes to apply and what parameters to use.
RONC
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Forum: Photographic Technique
09-24-2017, 12:52 PM
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I understand the statistics but there must be an associated movement to go with it. Are you assuming a one pixel maximum movement and how often is the movement relative to the exposure time?
The reason I is large jitter probably violates our assumptions about the statistics of both the signal and all noise types. We assume that the statistics are common for nearby pixels or other processes will fail in some way. This commonality is what really makes pixel shift so powerful. Just averaging a bunch of pixels without concern for their relationships to each other is not following what we know about good image processing methods. Super resolution sounds good but it, like interpolation, buys one little.
RONC
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Forum: Photographic Technique
09-24-2017, 07:58 AM
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Photoptimist,
Thanks for the response. I have a couple of comments and questions.
Being rather pedantic, I refrain from using the stack term with Pixel Shift as stack implies to most it is a summation or addition. I use composite instead. The green channel typically is not summed as only one value is used in PDCU, ACR, and RT.
In the last paragraph you have "% of pixel locations will be missing the pixel data." I have a general mistrust of the % sign (zero divided by zero???) and wonder how you derived the values for the channels.
I'd like to create a resolution display probably using a 2-D Fourier transform but have not found a way that is simple enough to be interrupted by the large knowledge difference across photographers. Resolution entails more than a cutoff spatial frequency but also the notches caused by sampling. If you might have an idea, I'd be willing to try it.
Regards,
RONC
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Forum: Photographic Technique
08-14-2017, 06:52 PM
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There are a number of items on the floor right now. I'd like to break off the spatial resolution part and with some assistance look at a method of estimating some information about the resolution of Pixel Shift on K 1 versus the resolution of a single frame from the same Pixel Shift dataset. Once we have a method agreed upon then we can try stacking the frames after removing the Bayer pattern, whatever super-resolution is....
If I can get a volunteer to supply the first part (Pixel Shift data), WE can try to measure resolution from it.
REPLIES:
Good idea?
Volunteers?
Just go away!
RONC
---------- Post added 08-14-17 at 21:23 ----------
Shooting with MC on you loose nothing if the jpeg is bad as you can generate one from the DNG without MC either in camera or PDCU program.
Not only are PixelShift files about 4 times a single shot DNG, there is a parameter in the MAKERS header that tells you it is PS.
RONC
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Forum: Photographic Technique
08-14-2017, 09:57 AM
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Unless you record true data no computer will give something real. Pixel shift and the Olympus algorithm use real data.
Pixel Shift doesn't increase the resolution passed the sensor sampling but it sure fills the spatial response closer to what can be done. Pixel Shift fills in 2/3 of the color information. A whole 66% without an interpolation!!! Even with the so called movement problem and a minimal compensation the data is better. Too bad the eye usually looks for anomalies rather than the loss of noise etc. What is truly hidden under the interpolation?
RONC
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Forum: Photographic Technique
08-14-2017, 04:08 AM
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OVF is optical view finder.
I'd like to see comparison of ACR (LR or PS) to Rawtherapee with Pixel Shift "movement correction" turned on. ACR has no correction at all. The correction in RT is highly superior to Pentax program version.
There have been a few hand held PixelShift examples pass by but none showed as being close to the tripod comparisons.
RONC
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