Lookup tables and subsequent measurements

Posted by Christopher Lloyd-2 on Apr 23, 2008; 7:40pm
URL: http://imagej.273.s1.nabble.com/Lookup-tables-and-subsequent-measurements-tp3696434.html

Good afternoon,

In the course of my research I need to change the greyscale values of 8-bit grey images that come
from an ultrasound machine to a new lookup table.  I've made the custom lookup table, and when I
apply this table to an image using Image -> Color -> Edit LUT... -> Open (and selecting the saved
LUT) you can immediately see that the displayed image changes to conform to the new greyscale
LUT.  However, the research involves looking at the mean greyscale value of a region of interest in
the image; application of the custom lookup table has no effect on the measurement values that
come out of ImageJ, either for the Analyze -> Measure route or for a line profile that is drawn in the
image.

So, my question is: can a lookup table be applied to an image that actually has some effect on the
measurements done on the image, or is the LUT a superficial way of viewing the images without
altering the underlying data whatsoever?  I couldn't find any matching inquiries in the archive, except
for one suggestion about going from grey to RGB and back (which didn't work, sadly).