Working with large image files

[wschlichtman]

I am running into speed issues when attempting to work with larger image
files, e.g., 5 M/Pixel photos. I have been experimenting with in-memory
working images which are scaled down to a more managable size. This seems to
work well, taking a GrayScale operation from 1850 milliseconds to about 300,
but then I run into problems when I wish to save work that's been done to the
image, such as a NoiseRemoval operation. The working file has been changed,
but the base file is unchanged and saving out the working file would lose
resolution.

Comparing my performance to something like Photoshop, I have found good
results using the working image, but the base image is not satisfactory. Am I
on the right track here, or are there better ways to work with the base image
and still get satisfactory performance?

Any help, including a good design text, would be greatly appreciated.