[guodong]

Originally Posted by naskies

Try using the Levels command with input levels of 50, 0.75, 245 - you'll see that the contrast increases dramatically, making the comet easier to see. The reason auto contrast/levels wouldn't work as well is that there's a big black silhouetted area that Photoshop won't "clip" - i.e. there's a big peak between 0 and 10, and then a flat part of the histogram between 10 and 50.

Thanks, Dave

It looks much better.

Cheers
Guodong