I wrote the following little program to shift the lines of a single band image by correction factors organized in the file "correction_factors.txt". ;; Program to shift lines by specified values for image with one band pro shifter_single_band ;; Open file with vector which contains the values each line has to be shifted by. The values ;; digitizing openr, 1, 'C:\idl pro\test\RSI\correction_factors.txt' a = intarr(1,45) readf,1,a ;; Read in image image_file = 'C:\idl pro\test\RSI\1_band_sub' ;; plug in image size x_image = 63 y_image = 45 imagesize = [x_image, y_image] image = read_binary (image_file, data_dims = imagesize, data_type = 12) ;; create empty array with populated with 0's new_image = make_array(200, 200, value = 0) ;; Shift each row by value specified in the vector "correction_factors.txt" for j = 0, 44 do begin b = (50 + a[j]) for i = 0, 62 do begin new_image[b,j] = image[i, j] b = b+1 endfor endfor ;; Write new image to spcified file openw, 2, 'C:\idl pro\test\RSI\1_band_output' writeu, 2, new_image end The resulting output image shows what I am expecting to see. Based on this result I was pretty sure that it would pretty easy to do the same thing for a multi band image. I just added another loop to take the third dimension into account and thought it would work the same way. However, I am getting not what I am expecting to see. The program I wrote for the multi band imagery reads as follows: ;; Program to shift lines by specified values for image with 240 bands pro shifter_240 ;; Open file with vector which contains the values each line has to be shifted by. The values ;; digitizing openr, 1, 'C:\idl pro\test\RSI\correction_factors.txt' a = intarr(1,45) readf,1,a ;; Read in image image_file = 'C:\idl pro\test\RSI\hyper_sub' ;; plug in image size x_image = 63 y_image = 45 z_image = 240 imagesize = [x_image, y_image, z_image] image = read_binary (image_file, data_dims = imagesize, data_type = 12) ;; create empty array with populated with 0's new_image = make_array(200, 200,240, value = 0) ;; Shift each row by value specified in the vector "correction_factors.txt" for Z = 0, 239 do begin for j = 0, 44 do begin b = (50 + a[j]) for i = 0, 62 do begin new_image[b,j,z] = image[i,j,z] b = b+1 endfor endfor endfor ;; Write new image to spcified file openw, 2, 'C:\idl pro\test\RSI\output_240_band' writeu, 2, new_image end It would be great if somebody could tell me what the problem is - I really appreciate your time and help with this Cheers, Jan