Olympus E-P1 A/D converter-10 bits

Discussion in 'Olympus Cameras' started by RobWatson, Jun 28, 2011.

  1. RobWatson

    RobWatson Mu-43 Hall of Famer

    I searched the forums a bit and came up empty on the bit depth or A/D converter for the camera.

    Quick check shooting a raw with most everything turned off (to minimize any processing) than inspect the histogram. Not just visually but actually get at the numbers. Pretty straight forwad to see how big the jumps in value are and then figure the A/D converter bit depth. In my case the software I use stuffs the data into the upper bits of 16 bit data word. Max value/jump gives the number of unique values. For the E-P1 there are 1024 unique values which equates to 10 bit A/D converter.

    It certainly is possible that there is something else in the camera but if the lowest level of access is through minimally propocessed raw images then 10 bits it is for all practical purposes.

    Pretty much any image histrogram will reveal this info unless completely blown to white (saturated) for every pixel.
  2. RobWatson

    RobWatson Mu-43 Hall of Famer

    Seems just because one can open a file does not mean it has opened correctly! I repeated the above but this time used Olympus Master 2 to convert raw into 16 bit.ch tiff. I extracted the green color channel. Histogram analysis shows >50,000 unique values ....

    How is this possible for a 12 bit A/D to give >50,000 values? Somewhere along the way some noise has been added to the image (after the A/D) that fleshes out the histogram! Not too worried about it as this noise does not reduce the SNR.

    I suppose it is time to build a photon transfer curve ...

    EDIT: I see I had NR on and NF low
    EDIT2: Even with these disabled there are >4096 descrete values ...