intensity mapping

[oaoao]

hello,if I have a image with  0~4095 level intensity,how can I choose some region like 1700~2000 level,and let this region mapping to 0~255 and save result to a new image or image txt file ?then I can try to use gradient colors to display this region!?  
I use lookup tables(16_color) and image-adjust-window level , will this process do intensity mapping this region to 0~255 display level? thanks.

[mal]

Part of the answer depends on what you need to do.  I assume you are dealing with a 12-bit monochrome image given the counts levels you inquire about.  Do you just need to see that region in greater detail, or are you trying to get calibrated intensity data from that region?  

If you just need to see it in greater detail, choosing a different lookup table can help.  If you go to the "Lookup Tables" option on the toolsets, it will put "Next LUT" and "Previous LUT" buttons on the toolbar, allowing you to scroll through them until you find one you like.

If you are actually trying to change the image, you can use the brightness and contrast menu (ctrl+sh+C).  Slide the minimum to your bottom range, and the maximum to the top of your range.  You should then be able to save it as an 8-bit image.  

If you want to automate this to a stack of images you could probably do it as a macro without having to get into programming, but automatically generating the filenames might be tricky.