Remove Colour Cast Using channels

[huxley]

How would I use channels to replace the blueish cast from the wheel set

[creeduk]

I wouldn't it takes a lot of platying because the problem here is in the cyan and green. Use hue and saturation to sort the blue tint.

[Ken Fournelle]

Try a Selective Color Adjustment layer

k

[Duv]

Perhaps another thought is to leave the blue alone and increase the red. This would bring it closer to medium grey and at the same time increase the rust color in the wheels.

Dave

[Kraellin]

excellent, duv!

and welcome to RP, huxley!

you could probably also use a curves adjustment layer and do pretty much the same thing that duv did using that.

Craig

[philbach]

Using Photoshop CS2 I just used adjustments auto-color and that removed a lot of the blue cast. Another easy way is to use Adjustment/Variations. The reason I like to use that is that you can see the results of adjusting hues before you make any changes.

[Flora]

Hi huxley,

Welcome to RP!

If you want to use the channels to remove the cyan/blueish cast from your picture, here is a way of doing it:

* In the channels palette, activate the Red Channel (the one needing correction here since the cast is cyan)

TIP: to acces the composite view while working on a single Channel, just press the ~ key after activating the Channel ...

* Go to Image>apply Image (Attachment 1):

Source Channel = Green
Target Channel = Red (automatically since it's the channel you are working on ...)
Blending = Screen
Opacity = 100%
Check the 'Mask' box keeping the default Options.

If necessary, apply some further selective corrections using either Hue&Saturation, or Curves, or Levels or Selective Colors

Working with PS CS2 I used a Shadow/Highlight Adjustment to decrease the highlights and, finally, I used USM to lightly sharpen the image... (Attachment 2)

[leuallen]

Try this, although it does not use channels.

Make a duplicate. Change dup to lab mode. Eyedropper tool, select a mid to deep blue on the box cover of the left wheel. Double click, foreground color to get Color Picker. Invert the signs of the lab a and b channel, if pos make neg, neg make pos. This gives you the "opposite" color of the blue, the color that when blended will produce gray. I assumed the area I picked was near gray.

Back to the original copy. Make a new layer with blending overlay. Fill the layer with the color from the dup. Adjust opacity some if necessary. I use about 55%

Discard dup image. You might be able to eliminate the dup image by just selecting color on original image and inverting signs in the Color Picker but that is not the way I learned it. There might be a subtle difference because of lab mode.

This gets close to eliminating the cast if you picked a good gray area. I might try a couple of different color selections, and pick the best. Then adjust color if required.

Without seeing more of the picture to make judgement from, it is difficult to tell whose color is more correct. You do realize that these shadow areas are inherently blue because of the sky. It might not be wise to to reduce them too much or you may get an unnatural look.

Larry

[Ken Fournelle]

Flora,

This is the third problem in a week in which you have used Apply Image to correct an image. I am not complaining; I find it fascinating, but where are you getting this all from? It's been great!

K

[CJ Swartz]

Ken, here's a tutorial for using Apply Image to eliminate redeye -
http://donskiff.com/getting_the_redeye_out.htm

Apply Image is used a good deal when trying to mask difficult elements in an image -- like hair

http://www.photoshopforphotographers...07_movie05.pdf

[Duv]

Larry, I really like your rendition but it looks like you're advancing from my post D-Caboose. If so, and so as not to add confusion, you should perhaps work and post from the original file so as everyone has a consistant starting and end point.

Cheers

Dave

[Ken Fournelle]

Thanks CJ

k

[leuallen]

Dave, you're right. Grabbed the wrong image. Here is one corrected from the original by the same process.

Larry

[nebgranny]

Well I have been learning how to use channels a bit by what has been going on in the forum. I used your instructions Flora. For some reason the hue and sat was greyed out , but when using the other function you mentioned this is what I came up with . a little different coloring than yours . I am using CS2 and my box looked a little different than yours. Neb

[Duv]

Originally Posted by leuallen

Without seeing more of the picture to make judgement from, it is difficult to tell whose color is more correct. You do realize that these shadow areas are inherently blue because of the sky. It might not be wise to to reduce them too much or you may get an unnatural look.
Larry

I think the correct color is the original post. Both the shadows and middle grey are very well balanced. The question is How do you make the image more personally appealing ie Colors you would see on a cloudy day. I noticed on a number of corrections, including mine, that had unusually high amounts of red in the shadows, the result of global corrections. Perhaps color changes should be thru masks on selected areas.

Dave

[Flora]

Hi everybody,

Ken,

sorry for getting back so late but I've been very, very busy (and will be for a while still....)

CJ pointed you in the right direction ... (thanks CJ!!!)

The first tutorial I read about using Apply Image (small brother of Calculations) is here.
.. and, after starting to understand what could be done with it, I started 'experimenting' with it while dealing with different problems ....

I use it regularly and it hasn't let me down yet ....

[Flora]

Originally Posted by nebgranny

Well I have been learning how to use channels a bit by what has been going on in the forum. I used your instructions Flora. For some reason the hue and sat was greyed out , but when using the other function you mentioned this is what I came up with . a little different coloring than yours . I am using CS2 and my box looked a little different than yours. Neb

Hi Neb,

what might have happened is that you were still working on the Red Channel only ... (Attachment1)

Make sure that before giong back to the Layers and opening the Hue&Saturation dialog box, you have activated all three RGB channels again .... (Attachment2)

P.S. I'm also using CS2 .... In your 'Apply Image' Box did you tick/Check the 'Mask' box under the Opacity Option?