LONG AND NARROW IMAGE

["Mark Chan" <chanm(at)cadvision.com>]

Given:
1 cm by 100 cm long continuous color photo (actual size). Saved in an image
format readable by IDL (e.g. READ_JPEG or equivalent). Cannot reduce in size
otherwise details will be lost.

Want:
Read into IDL. Display only 3 cm strip of the actual photo at any given
time. Which portion to show depends on some other parameter output from
another routine.

Problem:
1) Does any one have a similar code to share? If not, any web site that I
can get some idea on how best to do this? Any suggestion, especially on the
logic, is greatly appreciated.

2) I got a very grainy image when the image is displayed inside IDL. The
same image is very clear when displayed using a graphical package (e.g.
PhotoShop or equivalent). This is the first time for me on such topic. I
must be doing something wrong. Running IDL on WinNT4. Could it be color
indexing problem? Or resolution problem, etc? Want to improve quality of
image in IDL. Suggestions?

Thanks in advance,
Mark Chan