Hig res in studio scenes

Started 5 months ago | Discussions thread
hjs_koeln Regular Member • Posts: 109
Re: Hig res in studio scenes

You´re a regular education!

10-12 187mp images stacked in one single file - how much was a maxed out iMac pro again....?

knickerhawk wrote:

hjs_koeln wrote:

Somewhat off topic, but I was wondering about this: Is there be anything to be gained by making several multipass shots and stacking them in Photoshop/Affinity with less than 100% opacity each?

If by "multipass shots" you mean HiRes shots, then theoretically, at least, there should be some S/N improvement roughly comparable to the improvement you would get with a single shot taken for the aggregate amount of time as the combined aggregate time of all of the interim exposures used to construct the HiRes images you're combining.

It would increase dynamic range (maybe with diminishing returns considering the DR of multipass shots is already very high), but what about sharpness and detail resolution?

There would be virtually no improvement in spatial resolution (what you're calling sharpness and detail) without a corresponding movement of the camera itself between each of the HiRes shots, which of course would also require alignment of the stacked images. As a practical matter 4 shots is not enough to gain any visible spatial resolution increase when using this "super resolution" technique. You'd need a lot more. Given the size of these HiRes files, the idea of stacking a dozen of them or so just to squeeze out a tiny bit more resolution would surely not be worth the time and effort. Your computer will thank you for not trying it!

The one practical benefit I can envision for stacking/combining mulitple HiRes shots would be to reduce motion-based artifacts.

evan ts wrote:

knickerhawk wrote:

evan ts wrote:

There are many algorithms that can combine many low-res images into a single hi-res image.
(This one was announced 15 yeas ago: https://users.soe.ucsc.edu/~milanfar/publications/journal/SR-challengesIJIST.pdf )

I think that Silkypix just uses a newer and better hi-res algorithm than ACR.

But that's not what's going on at the raw converter stage to a HiRes raw file. The camera internally merges the subframes using a fixed algorithm (perhaps similar to what's discussed in the linked paper) and outputs an ordinary looking Bayer-style raw file, albeit a much larger one constructed from the subsampling of each normal-sized pixel position. The raw converters are not called upon to do anything different with one of these HiRes raws than they do with normal raws.

The hi-res takes 8 Bayer-shots (2 RGB-shots). The key point is, pixel size is still the same as a normal shot. When all shots are stacked together, pixels are overlapped. So we need a good algorithm to separate the information of overlapped pixels.

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