Hi Martin,

Good question - it feels like there should be an easy way to do this, but I don't know it either.

If you run

  print(getInfo());

for different images, as far as I can tell there's only a 'Display range:' specified for images that are neither RGB nor indexed color.  So combining both the bit depth and checking the info string could work:

isIndexed = (bitDepth() == 8) && indexOf(getInfo(), "Display range:") < 0;

if (isIndexed)

  print("Indexed RGB");

else

  print("NOT indexed RGB");

This doesn't feel ideal and probably isn't tremendously robust... so if there really is no better way, then that could be a good feature to request.

Pete

Hello Pete,

Thank you, I like your solution and will use it rather than mine :-) I did a simple function to check whether a LUT of an 8-bit image is linear, meaning the difference from one value to the consequtive value remains constant for all arrays R, G, and B.

function isLinearLUT(){

isLinear = true;

if(bitDepth() == 8){

getLut(r,g,b);

rDiff = abs(r[1]-r[0]);

gDiff = abs(g[1]-g[0]);

bDiff = abs(b[1]-b[0]);

isMax = false;

i = 2;

while(isLinear && !isMax){

if(abs(r[i]-r[i-1]) != rDiff || abs(g[i]-g[i-1]) != gDiff || abs(b[i]-b[i-1]) != bDiff)

isLinear = false;

if(i == lengthOf(r)-1) isMax = true;

i++;

}

}else isLinear = false;

return isLinear;

}

if(isLinearLUT())

print("Linear LUT");

else

print("Non-linear LUT");