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/
[2]
https://www.researchgate.net/publication/49654779_8-Bit_or_11-bit_monochrome_displays-which_image_is_preferred_by_the_radiologist
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