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| p.2 #4 · Dynamic Range vs. Tonal Range |
I was trying to avoid this thread since it require brain power to read and comments. Now I am waiting for my daughter piano class. Here are some of my thoughts.
All based on my understanding so I am open to be corrected:
DR of camera is purely defined by the sensor technology. As others have point out nowadays all manufactures have chosen ADC have high bit to cover the range so that sensor itself usually is the limited factor. So here is not much I can talk about. We all know that Sony based sensor is the best as for now.
In terms of TR, I was thinking that we don't need 14 bit ADC or thought high bit ADC has no advantage given sensor is the limited factor. But now, consider TR, make me want take it back.
There is benefit to have more bits of ADC to start with.
First, let assume there is two camera with sensors capable capture 8bit DR (or 50dB SNR, so signal is 2^8 bigger than noise). one with 8 bit ADC, the other with 12bit ADC.
There is an image has low DR, say 4 bit. the first camera with 8 bit ADC can only capture 2^4 resolution/step of tonal level, The same image captured by 2nd camera will capture 2^8 resolution level for the same 4 bit dynamic range image. So you can do the math here, there is a lot more information capture by 2nd camera even the image has the same DR.
Once you convert captured image to 8bit jpeg, obviously you have more tonal range and freedom to PP with 2nd camera. To the extreme, you can even remap the image to full 8 bit DR.
So in reality. It is not just DR make the image, but also TR, color response, and many things else. I agree with Sony sensor is capable to capture huge DR compare to Canon, but, but do we really need information the 2X, 2^2 or 2^3 smaller black? More DR, obvious better, give people more freedom to PP their images. But it is hugely overrated I think once consider how much it impacts image quality.
Since all those 14bit DR has to map to 8 bit JPEG, I fail to understand what is so fussy about Canon's files. I might miss something here, welcome to explain to me.
For lower DR images, some camera just has more TR with carefully design ADC/RAW algorithm. Have more bit ADC does offer more freedom to remap tonal range digitally, give photographer more freedom to achieve final results they wanted. (I think)
Since my field is electrical engineering, I have good understanding for signal processing, ADC/DAC, but not much about how raw, jpeg, print, gamma etc...works. I am open to any correction.
Just offer some food for thinking.
Edit: edit my original iphone content to make it readable. A little detail to explain tonal range and benefit of more bit ADC in sensor.
Edited on Apr 21, 2013 at 06:46 AM · View previous versions