Color Correction Problem

[EuropeanMan]

I have a DVD9 (http://www.sendspace.com/file/gobfow) sample here that I'm working on to remove the lilac/purplish tinge from the snow in the background. I'm having difficulties trying to find the right balance.

Any advice would be great.

Here is my script so far...

hdragc(shift_u=-10,shift_v=-90)

And a screenshot:

http://maxupload.com/img/8C3F560B.png

Source is on bottom, my work is the top half.

As you can see, the purple is almost gone, but has left alot of green...


Mods, please forgive me if I've posted in the wrong section...thanks in advance.

[setarip_old]

If you have the ability to adjust hue, saturation, and luminance, try the following:

Hue +25%
Saturation -10%
Luminance +60%

[mpucoder]

I got about the same values in PSP as setarip_old, but the hue was a negative value. The sign of the hue change depends on which program you use (hue is a 360 degree phase angle)

[um3k]

Hue isn't really the proper tool to use for color correction, methinks. This seems more likely to be helped by something along the lines of a curves filter.

[unskinnyboy]

If you want to fine control the red, green and blue channels separately, you'll need to convert to RGB32, but if you do that, then loading and using VirtualDub filters in Avisynth would be a better way since there are better VirtualDub filters to deal with this, than the Avisynth ones. In Avisynth, you'd have to work with all the colors together.

That said, here is a quick 'n dirty attempt with Autolevels (http://www.sendspace.com/file/7i6yx0):

http://img207.imageshack.us/img207/412/sample01ma7.th.png (http://img207.imageshack.us/my.php?image=sample01ma7.png) http://img156.imageshack.us/img156/4985/sample02gd8.th.png (http://img156.imageshack.us/my.php?image=sample02gd8.png)

Note: Not sure if it'd work for all of the movie though. Scene changes _may_ have problems since the scene change detection algorithm here isn't really "intelligent".