Hopefully this is not too basic a question. How do I transform a grey value measured on a converted 8-bit image back to its original 16-bit value? I have a method (described below) but not sure it is giving reliable results
I am interested in extracting the mean grey values of bone in a whole body CT of mice and then comparing mean values of groups to values from a phantom. My original images are 16-bit signed RAW files.
I then thresholded out the bone as a 8 bit binary stack. Then I used image calculator to subtract this image from an 8-bit version of the original, leaving only pixels with bone with values higher than zero.
My understanding is that the 8-bit conversion transforms the 16-bit values with maximum becoming 255 and minimum 0. Therefore, I have to convert back to 16 bit to compare between different individuals and to grey values of phantoms.
To do that I wrote a linear equation for each stack using (0, 16 bit minimum) and (255, 16 bit max grey value). I then plug in my mean bone value to get the original 16 bit value for each stack. Is that correct or am I wrong?
Hope this is not too confusing.