The signal intensity of a gray level image with R,G,B indices (hdr file) changes every time the image is multiplied by different binary images (derived from object maps).

I have a 2D gray scale image 'I2' (attached, initially 'hdr' file derived from Analyze) which however, contains R,G,B indices. When I multiply my 'I2' image by different binary images 'BW', 'BW2', 'BWZone' (also derived from Analyze, see code below), the signal intensity is slightly changing and the R,G,B indices are changing as well. Have a look in my code:

I2 = double(I); %change to type double so that we can use NaN's

filter_I = I2.*BW; filter_I2 = I2.*BW2; filter_IZone = I2.*BWZone;

Unfortunately, options such as 'rgb2gray' (etc.) don't apply here to eliminate the R,G,B indices. All I need is to maintain the same gray level values when I do the multiplications. I attach here all files. Any ideas, much appreciated.

Thank you for your time.

George