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  1. Ted Cousins

    Dynamic Range versus Bit Depth?

    See: https://docs.gimp.org/2.10/en/gimp-image-precision.html I have GIMP V 3.2 The link has a telling caveat "regardless of which options you choose in the Precision menu, in high bit depth GIMP 2.10 all internal processing is done at 32-bit floating point precision, and most editing...
  2. Ted Cousins

    Dynamic Range versus Bit Depth?

    I have no idea nor do I care.
  3. Ted Cousins

    Dynamic Range versus Bit Depth?

    no comments received yet, so researching GIMP Help solo.
  4. Ted Cousins

    On the interaction of quantizing with read noise and the like

    Excellent note on the quantization of photodetector output voltages, Doug. Greatly appreciated, Ted.
  5. Ted Cousins

    Dynamic Range versus Bit Depth?

    Oh. Here's how:
  6. Ted Cousins

    Dynamic Range versus Bit Depth?

    I think that the image data in 12, 14, and 16-bit raw files is contained in word form i.e. within word boundaries. In other words, 12-bit ADC data is not stored as 8 bits in one byte and 4 MSBs in the succeeding byte; then 4 LSBs in that succeeding byte followed by 8 MSBs in the next byte. So...
  7. Ted Cousins

    Dynamic Range versus Bit Depth?

    As to DR versus bit "depth" I may be able to make comparisons in the GIMP. The GIMP is able to work in various degrees of precision, namely: 8-bit integer 16-bit integer 32-bit integer 32-bit floating point Each linear, or perceptual (with gamma). Not only that, but any part of a image can...
  8. Ted Cousins

    Dynamic Range versus Bit Depth?

    With reference to Jerome's input where the "noise floor" is mentioned, the Standard requires temporal(?) noise measurement at a "reference black" level of 1% of almost saturated. Doug's article refers mainly to a processed image, say for example a 16-bit TIFF such as can be output by LibRaw's...
  9. Ted Cousins

    Dynamic Range versus Bit Depth?

    Some people think that 16-bit has more dynamic range (DR) than 8-bit. I've never fully understood that view ... for example 65535/0=infinity and so does 255/0=infinity, ergo it can't be just the bit depth that gives "more" DR ... and avoiding the division-by-zero by selecting say 1 as the lower...
  10. Ted Cousins

    Norwood's dome lives on

    The second attachment in my post ... "A", your "shot 4" ... you had asked about 1 versus 4. best, Ted.
  11. Ted Cousins

    Norwood's dome lives on

    One way, Doug: I observed linear histograms in the GIMP ... same mean value 0.422 and median 0.314 - but "head on" is std. dev. 0.220 vs. 0.208 at "side". Significantly more contrast "head on". So the exposure results were about the same and I preferred the side-lit look. best, Ted.
  12. Ted Cousins

    On standard aperture values

    Thanks. So one would not expect a factor of exactly 10 for every 20 steps in that theoretical column. (about 10.08 according to my Casio). best, Ted.
  13. Ted Cousins

    On standard aperture values

    Doug, is the column headed "series Theor." based on the 6th root of 2, or is it based on the 20th root of 10? I'm guessing the 6th root of 2 because the 6th root of 2 raised to the power of 20 is not exactly 10, only close. best, Ted.
  14. Ted Cousins

    On standard aperture values

    FYI, the source: https://en.wikipedia.org/wiki/F-number best, Ted.
  15. Ted Cousins

    On standard aperture values

    Going back a bit (1899): 𝑓/LOL, Ted
  16. Ted Cousins

    On standard aperture values

    Out of interest, here are what values appear on my Sigma SD10 LCD in the mounted lens range minimum 𝑓/2.8 to lens max 𝑓/22, camera does 1/3 stops. I speculate that there is a string array in the firmware for these indications because the control dial is not marked. I wonder: if I change the...
  17. Ted Cousins

    On standard aperture values

    Hi Doug, Perhaps ISO 517 is only addressing lens actual value markings: So that could be why they don't shows lists of intermediate markings per se? Even though they say ... ... I don't think they mean markings with values, although one might think so at first. Most if not all of my lenses...
  18. Ted Cousins

    On standard aperture values

    Yes, the 6th root of 2 in Libre Calc also matches ISO 517's 1/3-stop listing ... ... still playing ... main purpose is rounding
  19. Ted Cousins

    On standard aperture values

    Hi, again, I wondered about that ... still playing trying to match ISO 517's listed 1/3 stop values "I'll be baack"
  20. Ted Cousins

    On standard aperture values

    Hello, Doug, How about some extreme theoretical values?! After some playing, I got Libre Calc to do a series starting at 𝑓/0.5 based on the 6th root of 2, voila: I tried some rounding and failed ... ... I'm beginning to think that there is no published rounding method that matches the de...
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