Need help to work with large files

[cogito]

Hi,
I need some help with operations on large image file, the goal of this operations is to prepare data for application so it will be able to display map of some area, and on request put it all back into one file.
So in general there are 2 operations required, first is to take huge image (30000x30000) or more and cut it into tiles, lets say 1000x1000 each. Repeat this step to create tiles for resized image or resize tiles (whatever is faster). This will create tiles for 100%, 90%... 10% of original image. This tiles will be used on web site to display map with ability to add some markers and elements. On user request the 100% tiles can be composed back into one huge image (or I can use original 100% image) with added markers and elements, so the map can be printed from one file.

My question is how to perform this, and what file format will work the best... jpeg seems to result in "no enough memory". Png? or bmp? I can reduce number of colors.. the problem I have found is that depending on actual image, size (I can say what is the most important factor) the slicing or even resizing, format conversion is taking ages.. imagemagick is consuming small amount of memory and CPU and looks like not doing anything.

It would be great if someone can share some ideas how to approach this task

[fmw42]

I have never worked with files that large. All I can do is suggest you review http://www.imagemagick.org/Usage/files/#massive. I have no experience with this so it is just a suggestion.