http://www.perlmonks.org?node_id=985259


in reply to How can I predict which image will big smaller ?

Did you read the documentation?
... especially
# try to save in one of these formats
SAVE:
"
(assumption: you mean smaller file size).

Or, "# Create smaller version
# documented in Imager::Transformations
"
if "smaller size" refers to dimensions in pixels.