Dear IDL user, I want to merge a low-resolution color image with a high-resolution grayscale image by means of ENVI image sharpening (HLS). From the ENVI4.2 user¡®s guide : transform/image sharpening, I not only learned how ENVI performed the HSV and HLS sharpening, but also that HLS sharpening can be performed the same way as HSV if some of the parameters in the routine RGB_TRANS_DOIT are changed. Because I am a new user of ENVI, and I knew very little about the IDL. I sincerely hope someone can tell me how to change the routine RGB_TRANS_DOIT, and when the routine is changed, how to use it to image sharpening? Any suggestion will be appreciated. I am waiting for your reply. Liping