DrDivx and psychovisual enhancement

I know you are all going to boo me for using DrDivx but it does work for me. Can anyone tell me what the setting "psychovisual enhancement" under the pre-processing tab does. The setting choices are off, shapeing and masking. I do a lot of .ts HD stream processing and output the stream to a 1280x720 divx file. I also upconvert standard DVD content to a 1280x720divx file. So I guess my questions are. 1. What does psychovisual enhancement do. 2. What does each setting do. 3. Would it benefit me to use this setting considering the type of encoding I'm doing?

While I don't know DivX enough to give you a specific answer, psychovisual enhancement is enhancement that usually decreases objective quality metrics such as SSIM/PSNR but increases visual quality as perceived by humans. One example of a psychovisual enhancement is Adaptive Quantization in x264, which allocates more bits to dark background areas to reduce blocking, which reduces quality metrics but generally helps visual quality.

maybe some DivX guy may enlighten us.