The histogram in Photoshop for a 16-bit image downsamples to 8 bits, showing a tonal range of 0 to 255. I appreciate to show tonal ranges for a 16 bit image a horizontal zoom function would be necessary.
However the mean, std deviation,... statistics also get downsampled to 8 bits with a corresponding loss of accuracy.
Is there a way of seeing the true mean, std deviation etc of a 16 bit image?
A lot of tools do this by default (even matlab's image processing tools for the most part). I'd load the image up in matlab and use the hist, std, mean, etc function by treating the image as a vector. Tools like EnvI also handle 16 bit images properly.
The matlab/octave code would be roughly as follows (assuming 16 bit greyscale png):
img=double(imread('image.png'));
mean(img(:))
std(img(:))
hist(img(:),number of bins)
