Fengtao,
In DVD to Mobile mode, the converted videos look darker than the original. The quality of the converted videos could be much better if some type of "auto contrast and brigthness" is implemented. This can be quite a sophisticated feature with full control and preview for contrast, brigthness and gamma however it seems most videos just need a "standard" correction and probably just a "tick box" for auto correction of contrast and brigthness can be very useful and easy to use. Thank you .