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Re: Re: Acquiring Dental RVG on Linux

On Wed, Jan 06, 2021 at 05:13:58PM +0530, Sonali Warunjikar wrote:
> I think distance calibration is over. Now over to other image parameters.

Some observations about depth (bits per pixel):

- The proprietary software is producing images with only 8 bit depth,
  throwing away half of the data (data is 12 bit + 4 filler bits) gathered
  from the sensor.

- Most monitors available commercially do not support a depth > 8 anyway.
  Special purpose monitors with higher depth aren't easy to find (might be
  costly if found). Practitioners aren't seen using them anyway.

- "Even for high brightness and high contrast medical displays with
  luminance range between 0.5 and 2000 cd/m2, the human observer can
  perceive no more than around 900 shades of gray" [1]

  This means at the most 10 bits can be relevant for human consumption.
  It's a different matter if the images are to be analyzed by software.

- "The radiologists did not attest the higher grayscale resolution a
  better image quality, they regarded the 8-bit technology to show a
  better sharpness and contrast, although this had no impact on the
  detectability of details." [2]

  It could be that the extra grey shades result in showing more fragmented
  view which the practitioners aren't accustomed to after years of
  practice with 8 bit depth. (My speculation.) And it's not going to be
  easy to make them adapt a higher depth.

So in summary, I am just going to follow the suit and throw away the first
byte (it's little endian) and resort to 8 bit images in pyrvg software. It
will also open up the choices of image handling software as many of even
widely used ones do not support depths > 8.

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3043920/

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