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Archive 2018 · Does down-sampling increase tonality?

  
 
stompyq
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p.1 #1 · p.1 #1 · Does down-sampling increase tonality?


Just a very basic question. If you take say a 64 mp 12bit scan of a negative (or even a 64mp 12 bit file from a digital camera) will down-sampling in photoshop to a lower mp (say 16mp), increase the apparent tonality?


Jan 11, 2018 at 04:59 PM
John Wheeler
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p.1 #2 · p.1 #2 · Does down-sampling increase tonality?


Hi stompya
There may be something behind your question based on your observation or experience that made you bring this question to the forum. If so, it might help to understand that background.

First I will limit my answer to the negative scan because 12 bit camera files are raw files which is different ballgame.

In general and practically, for most images you should not see changes in tonality assuming that you are referring to the range of highlights to shadows in the image.

However, academically, if you have very high frequency components that were also very high contrast in your image, you can have a shift in tonality. If the limit, I could create a b&W checkerboard pattern at the pixel level, then reduce the size of the image by 50%, and with most rendering algorithms, it would turn the image from all balck and white to solid gray.

Hard to answer your question with much more detail without more background of your questioni and also yrou own definition of tonality.

Hope this helps some



Jan 11, 2018 at 06:04 PM
Peter Figen
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p.1 #3 · p.1 #3 · Does down-sampling increase tonality?


Certainly when you downsample you tend to get smoother gradations and less appearance of film grain or digital noise. It can make it seem like you're getting better tonality, but it might just be the illusion of looking at a lower resolution image. It might also depend on the quality of your film scanner as well when you're referring to film. The better scanners have smoother tonal gradations to begin with, with greater tonal range as an added benefit. Hard to see if 8, 12 or 16 bits make a difference in what you see on screen as your monitor is only 8 bits per channel at best.


Jan 11, 2018 at 09:16 PM
stompyq
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p.1 #4 · p.1 #4 · Does down-sampling increase tonality?


I suppose I should have been more specific. I was thinking about stitching multiple RAW files from micro 43 camera in to one larger file. I've always felt the tonal transitions are much more abrupt in m43 vs FF and have been trying to figure out a way to increase the tonality (at least by a small amount)


Jan 16, 2018 at 11:13 AM
Peter Figen
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p.1 #5 · p.1 #5 · Does down-sampling increase tonality?


In your original post you were referencing film scans and now you're talking about stitching raw digital camera files from a micro four thirds camera. The tonal transitions are going to be based your camera sensor and the software you use to process the raw files.


Jan 16, 2018 at 12:53 PM
stompyq
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p.1 #6 · p.1 #6 · Does down-sampling increase tonality?


Peter Figen wrote:
In your original post you were referencing film scans and now you're talking about stitching raw digital camera files from a micro four thirds camera. The tonal transitions are going to be based your camera sensor and the software you use to process the raw files.


Yes I was thinking ahead to film scans as well. I don't use a scanner. I use a DSLR to scan my negatives and stitch. I guess I should not have confused everyone by putting that in there. My immediate interest is in stitched micro 43 images



Jan 16, 2018 at 02:05 PM
Alan321
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p.1 #7 · p.1 #7 · Does down-sampling increase tonality?


If possible, stitch the images with all details available, and then dumb it down as required. Not all software can handle all the detail. Consider PTGUI, as it is good for letting you precisely specify match points on adjacent images. That ability may overcome any issues caused by noise or grain.



Jan 19, 2018 at 08:30 AM





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