Q:
I’ve optimized a file both in Acrobat and PDFNet. In each, I set the options to prefer JPEG compression. (In PDFNet, this is done with Optimizer.ImageSettings.SetCompressionMode(e_jpeg).) I set the PDFNet compression level to 9 (using Optimizer.ImageSettings.SetQuality()) and the Acrobat compression level to “Medium”. The PDFNet output is much larger. Why?
A:
After analyzing the quality of JPEGs output from PDFNet and Acrobat at different levels, it seems that Acrobat’s “Medium” level approximates PDFNet’s quality level “3”. Here is a table of the correlations we’ve found between settings in each:
Acrobat … PDFNet
Minimum … 1
Low … 2
Medium … 3
High … 4-6
Maximum … 7-9
At these settings, Acrobat and PDFNet also create similarly-sized JPEGs.