Benny Class 1 Session 2 Example 5

Posts: 4927
Joined: Fri Sep 20, 2013 8:29 pm

Postby mikemeister_admin » Sat May 26, 2007 12:26 pm

This photo was taken in an underground winery in New Zealand. Obvious color cast because of lighting.
LAB does a good job or removing the cast after setting neutral around the top right area of the tunnel wall.
A little saturation brought out the timber colour in the wine casks. There is still a green cast (I presume) on the end wall.
How to get rid of this?
The RGB image neutral set image appears similar to the LAB image, aslo with green back wall.
When setting the neutral in RGB is there an ideal RGB reading to look for in the hue clock? Is it 128,128,128?

Posts: 4927
Joined: Fri Sep 20, 2013 8:29 pm

Postby mikemeister_admin » Sat May 26, 2007 12:31 pm

On closer inpection the RGB neutral image appears to still has a red color cast around the wine casks.
Can a second or third neutral point be applied to get rid of this red color cast (and any others that appear)?
Also once all color casts have been removed in the RGB image can the colors be made to stand out further by other curve adjustments or would I then have to open it in PS to apply color saturation.

Posts: 5342
Joined: Wed May 24, 2006 2:15 am

Postby ggroess » Sat May 26, 2007 2:11 pm

One of the things you can do is make changes in stages. 

i.e. use lab to fix the overall color. save the change.
re-open the image in CM and use RGB to adjust local color shifts. save the change.
open the image in CM using HSB to add saturation to the colors. save the change...

This is one possible workflow...we do not want to limit you in this.  You can add the CM to your process in any place you want.  I would say that sometimes the Photoshop tools do a better job on an image than the CM tool or that they can make a faster correction and then finish the process in CM. 

If the goal is a good image, we don't want to limit you in your choices.  You are free to use all the tools at your disposal to achieve that goal.  We would hope the CM tool is a very important one to you.  It is to me...but you certainly have to make it work for you.  One of the goals for the classes is to have the CM tool be easy, fast and powerful.  If it is then you will use it all the time.

BTW the green in the back wall might actually be there and is being masked by the pressure lamp color...


Posts: 1916
Joined: Thu Mar 26, 2015 1:53 am

Postby -default » Wed May 30, 2007 8:15 am


This is a very interesting image for several reasons, and you are doing and thinking about the right things.  For the time being, I would trust the metal to be neutral.  Setting a neutral on the metal puts the wood at about 12:30 on the hue clock.  The floor, and left and right stone walls become somewhat warm with this treatment

The unacceptable green cast on the back wall and light is characteristic of an Lab correction.  Normally I would remove this with a second pass in RGB mode to curve only the bright part of the image, however in this case it took about 10 seconds to use the brush in color mode to "clean up" the green. I've attached the result.

Return to “May 2007 Curvemeister 101”

Who is online

Users browsing this forum: No registered users and 1 guest