The image compositing utility imf_comp is able to merge several
images of identical resolution into a final image based on the
alpha channel information of the individual images. Rendering
with mental ray using a camera window will result in images of
full resolution with only a smaller rectangular part filled with
actual content. It allows to render heavy scenes in smaller
pieces to save memory, or render very large resolution images in
parts that could not be rendered otherwise. The tool can be used
afterwards to glue the image pieces together easily and
seamlessly. Note, that if global illumination caches are used,
like finalgather maps, then those should be pre-computed at full
resolution to capture the full scene, and used later in read-
only mode for the rendering of the individual tiles. See the
example for details. The image compositing utility is started as
imf_comp [options] file1 [file2 ... fileN] It reads color image
files with an alpha channel, filen, and merges them seamlessly
into a final image