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07-07-2014, 03:09 PM   #16
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QuoteOriginally posted by vonBaloney Quote
The day is coming, as they have already accomplished this in research on a small scale...I've seen it. There is a paper describing it with examples posted around here somewhere. What it was...was they used extremely simple optics -- one or two element lenses that produced crappy blurry images but then applied the knowledge of the way the light was spreading etc (point spread functions and things I don't understand) to "fix it" in the computer and end up with images that look they were shot with much higher-end lenses. I don't see any reason why such ideas could not be applied to diffraction. I've actually been dabbling with something similar myself, but with a totally different approach (since I don't understand point spread functions, etc). I've seen similar "fixing" of motion-blurred images by use of motion sensors at capture time to record the vibrations. The idea (put simply) in either case is that the light is supposed to be here, but it is somewhere else instead (but still captured), and so if you can model or have a profile of the way it went wrong, you can undo it and put the light back where it is supposed to be. Seems like making a diffraction profile of a particular lens at a particular aperture would actually be one of the easier and most obvious applications of such tech, and so it starts...
Your witness Imageman? Since my explanation got an "lol" Maybe someone else can make sense to you.

07-07-2014, 04:46 PM   #17
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First my lol was not about your explanation of what may be possible given enough development and expenditure of cash, but it was my amusement that were still in disagreement on this.


I don't believe that cutting edge techniques are going to be applied here when simple sharpening will deliver the required results.


Olympus have stated categorically that in their implementation of optical diffraction compensation, all they are doing is sharpening and nothing else.


I quite agree that if you capture light in new ways that allow post exposure refocusing, a technique which does exist, and works, where an out of focus image is reprocessed and sharpened using alternate light rays already captured at exposure time, you can compensate for focus errors and anomalies in post processing.


But this discussion I thought was not about what is possible or conceivable, instead I thought it was about what Olympus and Pentax intend to implement to compensate for diffraction. That surely has been answered, its simple sharpening.


The other resharpening using multiple captured light rays demands, a different kind of lens and a 40 megapixel sensor that gives a 10 megapixel image, the unused 30 megapixels captured are the alternate light rays some of which are used in refocusing.


This technology will not be embraced in compensating for diffraction. What the engineers are seeing when diffraction hits, is a loss of focus, and the decision is taken, how shall we fix this as easily and cheaply as possible.


They can compensate for diffraction quite successfully by simple sharpening. 90% of users will be more than happy with this solution. So that's the one that will be used.


Olympus have even said that is the solution they are using.


We are talking about different things here. This discussion was about what will they actually use to compensate for diffraction. That's what im speaking on. You are speaking it seems about what may be possible.


We can discuss at length different possible solutions, lens based solutions light ray based solutions. but the fact remains, Olympus are implementing a sharpening only solution. Pentax would be fools to invest heavily on some other complex system that performs no better.


I don't see a reason to get into a deep technical discussion when its very far off topic. The topic is, how will a diffraction compensation system be implemented here and now.


The answer seems obvious. Simple sharpening. Not many people will like it, but its cheap its cheerful and it works.


I don't understand why this is not being accepted so ill say it again. Olympus have stated that when compensating for diffraction they sharpen the image in camera. Can we not accept now that this is the method that's being used.


Im not trying to say you cant do it by other methods. Im saying what theyr actually using. If you have a problem with what Olympus are doing maybe you should take it up with Olympus and tell them theyr wrong and they should be using your method to compensate for diffraction. And I believe where Olympus have gone Pentax will follow.


Don't shoot the messenger.
07-07-2014, 05:25 PM   #18
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If diff.comp is just an option for K-3/645Z JPG's, like the current firmware options for CA correction and vignetting compensation, so be it. Not a big story. It might work OK, and may even have options for the strength of the effect (Off | Low | Medium | High).

I seriously doubt this will be something they attempt to have compulsorily baked into camera RAWs.

Anyway, the 645Z is on the streets already. Maybe someone already using the camera is able to comment on how diff.comp works on the 645Z?
07-07-2014, 06:32 PM   #19
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QuoteQuote:
The answer seems obvious. Simple sharpening. Not many people will like it, but its cheap its cheerful and it works.
Actually, you don't know anymore about how 645z diff comp works than I do... so you're as much speculating as I am. I suppose next you'll tell me Pentax shake reduction doesn't exist, because Nikon and Canon do it in their lens. or the K-3 AA filter doesn't exist because Olympus doesn't do it that way. Or maybe TaV doesn't exist, because no one else has it. Your line of logic here is fraught with peril.

07-07-2014, 06:51 PM   #20
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Diffraction Compensation adds little to manufacturing costs per camera. It's obvious Ricoh is doing it in software if it can be added to existing K-3 cameras via a software update. There's a one-time software design cost whether "simple" sharpening (just at a more extreme level at small apertures) or a more complex miracle algorithm is being used.
07-08-2014, 01:41 AM   #21
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There's a recent short thread on DPR about Sony doing diffraction compensation in the new Bionz X chip in the A7R and a few other recent bodies. Does deconvolution processing count as sharpening? Deconvolution is what the Sony process is described as.

It seems everyone - Olympus, Sony, Pentax, Fuji I think - is now doing diffraction compensation.
07-08-2014, 03:47 AM   #22
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Seems to be well known in the field of microscopy. This article discusses the topic. Sounds to me like there is an algorithm involved to compute and "reverse" the effects of diffraction.

From the article:
"The most significant source of blur is diffraction, and an image whose resolution is limited only by blur is considered to be diffraction-limited. This represents an intrinsic limit of any imaging system and is the determining factor in assessing the resolution limit of an optical system. Optical theory proposes sophisticated models of blur, which can be applied, with the assistance of modern high-speed computers, to digital images captured in the optical microscope. This is the basis for deconvolution."

Edit: And:
"[...] because blur is a function of the microscope optical system (principally the objective), it can be modeled with relative simplicity. Such a model renders it possible to reverse the blurring process mathematically, and deconvolution employs this model to reverse or remove blur."
07-08-2014, 04:14 AM   #23
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I'm a jpeg shooter 97+% of the time and I'd welcome an automatic, in-camera diffraction compensation thingy. I'd happily leave it on, knowing that it will only take effect at small apertures, and at just the appropriate amount.

Sometimes I see f/18 when doing fill flash work in P mode in sunshine. The next shot may be only f/11. An automatic solution would be great here, for me in my jpeg shooting.

Regards,
--Anders.

07-08-2014, 04:49 AM   #24
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Diffraction is diffraction - full deconvolution sharpening methods are computationally complex, far beyond the computational power present in DSLRs today*. You would have to have diffraction profiles for each an every lens, at every focus setting and focal length to make it work as designed. Olympus are simply applying a higher level of sharpening as the lens aperture gets smaller. Simple, cheap and people will love them for it.

Once information is lost it is gone forever, sharpening is a blunt tool we throw with the aim of trying to defeat physics.



*though a simplified optical model could be used for deconvolution, however it would produce results of questionable precision.

Last edited by Digitalis; 07-08-2014 at 04:57 AM.
07-08-2014, 08:20 AM   #25
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QuoteOriginally posted by Digitalis Quote
Once information is lost it is gone forever, sharpening is a blunt tool we throw with the aim of trying to defeat physics.
It is not lost, it is scattered. If scattered by a predictable process, then it can be undone (at least to some extent). If it is totally random, then it would be probably be truly lost. (It isn't totally random.)
07-08-2014, 01:33 PM   #26
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QuoteOriginally posted by rawr Quote
It seems everyone - Olympus, Sony, Pentax, Fuji I think - is now doing diffraction compensation.
Hmmm, whatever that "compensation" might be, (real or purely cosmetic), I hereby declare the pixel-race for re-opened.
07-08-2014, 05:06 PM   #27
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Digitalis has it absolutely right:-


Diffraction is diffraction - full deconvolution sharpening methods are computationally complex, far beyond the computational power present in DSLRs today*. You would have to have diffraction profiles for each an every lens, at every focus setting and focal length to make it work as designed. Olympus are simply applying a higher level of sharpening as the lens aperture gets smaller. Simple, cheap and people will love them for it.


I completely refute the suggestion that Pentax is going to create a highly complex and costly system when their competitors use a cheap and simple system, such a suggestion is absurd.


I live in the real world, a world where manufacturers spend as little as possible to sell their product. No manufacturer in his right mind would create a complex and expensive solution when a cheap one will do.


If Olympus creates a diffraction compensation system, and its just sharpening, they can do it at zero additional cost and sell product.


If Pentax creates their own version of a diffraction compensation system, and due to its complexity it puts 50 or 100 dollars on the cost of the camera, they wont sell any cameras of that model.


That's the reality. A business case for such a high tech camera would fail.


Now will somebody explain what Pentax are actually doing so we can end this.


Lets use some common sense here.
07-08-2014, 05:31 PM   #28
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None of you guys have a clue.. Pentax sent in the pixies that's all they did.

Seriously though; Convolution matrix processing based on Pentax lens profiles that allow subtractive processing of diffraction based blur (extra images) might well be possible in-camera. Those bright spots you see on the ground in the shadows of trees are images of the sun caused by diffraction and so it seems quite plausible that there is a way of removing "ghost images" caused by diffraction within the main image. Just how many of these "images" you remove, and to what extent, will depend on your CPU I suppose. I assume that the heaviest diffraction-based interference would occur at the intersection of the diaphragm leaves and so it may only be necessary to remove "ghost images" created by these to clean up affected images to a respectable degree.

Like everyone here I am merely surmising and thinking out loud.
07-08-2014, 06:08 PM   #29
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Yikes. Happy hour on this thread?

Restricting it to diffraction, I don't think the tech is very complex.
Transfer functions by the convolution integral with the delta & step etc has been around in public domain for at least 65 years. (ever had a Spirule in the bag with your slide rule?)
There is a good amount about it in imaging context in the literature, as i read with some brief search today.

My query is, neglecting macro, micro and astronomy, what are the smallest f/- on the Pentax 645 lenses?
How sharp are 645 photos taken at smallest f/-?
Can anybody post a good photo at smallest aperture?

Regards

Last edited by wombat2go; 07-08-2014 at 06:15 PM.
07-08-2014, 06:28 PM   #30
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Maybe this new diffraction algorithm is the "unique thing" Pentax is going to introduce with it's FF.
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