Bias green/magenta white balance value? at DVinfo.net

Dustin Moore · June 1st, 2011, 12:41 PM

I'm pondering a white balance problem. White balancing generates two
offsets, one in red<->blue and the other in green<->magenta.

I see that in the EX1 picture profile setup I can bias the white balance along
the red, blue axis. Is there another setting somewhere that effectively adds a
bias along the green<->magenta axis? I was looking around and the NEX 5
camera has this functionality.

I need to make relatively small adjustments in the magenta direction
and making custom tinted white cards is a pain/complicated.

Thanks for any ideas,

Piotr Wozniacki · June 2nd, 2011, 03:04 AM

Quote:

Originally Posted by Dustin Moore

I'm pondering a white balance problem. White balancing generates two
offsets, one in red<->blue and the other in green<->magenta.

I see that in the EX1 picture profile setup I can bias the white balance along
the red, blue axis. Is there another setting somewhere that effectively adds a
bias along the green<->magenta axis? I was looking around and the NEX 5
camera has this functionality.

I need to make relatively small adjustments in the magenta direction
and making custom tinted white cards is a pain/complicated.

Thanks for any ideas,

Unfortunately, I can only confirm your findings. It happened to me many times that using a PP's preset WB in a somewhat tricky lighting situation, the green/magenta was badly off; only WB-ing to a white card could correct it...

Piotr

Leonard Levy · June 6th, 2011, 01:27 PM

Yes - in the same offset menu is a setting for phase. That adds magenta or green.
To fix white balance carry around a 2x2 lighting swatchbook with Plus and minus green gels in it.

Dustin Moore · June 6th, 2011, 02:07 PM

Ok, interesting. I'm not quite up on all my color theory but I think phase would rotate
the color vector around the center of the vectorscope. With the color bias I can offset
white left and right on the vectorscope. What I'd like to do is shift the white
up and down on the vectorscope. If I rotate it on the vectorscope, that is not the same
thing as shifting.

I think the phase control does everything but shift white in the green magenta direction.
I need to get a set of green/magenta cards, looks like the only way.

Many thanks,

June 1st, 2011, 12:41 PM	#1
Dustin Moore Regular Crew Join Date: Apr 2011 Location: Rochester NY Posts: 104	Bias green/magenta white balance value? I'm pondering a white balance problem. White balancing generates two offsets, one in red<->blue and the other in green<->magenta. I see that in the EX1 picture profile setup I can bias the white balance along the red, blue axis. Is there another setting somewhere that effectively adds a bias along the green<->magenta axis? I was looking around and the NEX 5 camera has this functionality. I need to make relatively small adjustments in the magenta direction and making custom tinted white cards is a pain/complicated. Thanks for any ideas,

June 6th, 2011, 01:27 PM	#3
Leonard Levy Trustee Join Date: Feb 2006 Location: USA Posts: 1,684	Re: Bias green/magenta white balance value? Yes - in the same offset menu is a setting for phase. That adds magenta or green. To fix white balance carry around a 2x2 lighting swatchbook with Plus and minus green gels in it.

June 6th, 2011, 02:07 PM	#4
Dustin Moore Regular Crew Join Date: Apr 2011 Location: Rochester NY Posts: 104	Re: Bias green/magenta white balance value? Ok, interesting. I'm not quite up on all my color theory but I think phase would rotate the color vector around the center of the vectorscope. With the color bias I can offset white left and right on the vectorscope. What I'd like to do is shift the white up and down on the vectorscope. If I rotate it on the vectorscope, that is not the same thing as shifting. I think the phase control does everything but shift white in the green magenta direction. I need to get a set of green/magenta cards, looks like the only way. Many thanks,