red channel noise

[imported_julie]

Hi
I hope someone can explain something for me
The first step I take in colour correction is to go into the different channels and adjust in curvemeister for luminosity
I have begun to notice how noisy the sky is in many images in the red channel, but not the green or blue
if I end up replacing the blue channel with the red one the noise is really noticeable
Especially when sharpening at the end

I guess I want to know if this is a problem I am creating inadvertently, or if its just the nature of the red channel
Also if anyone has any solutions I would love to hear them

At the moment I am copying the sky into another layer and adjusting for noise - it works, but I wonder why it happens in the first place

Julie

[ggroess]

Julie,
Can you post an example and a sample curve so i can see if you are creating it inadvertently. 

I think that would be the most help.  Also what ISO are you setting on the camera?  Higher ISO settings are noisy in every channel.

Greg

[imported_julie]

Hi
sorry for the delay in posting again
the images attached show the original and all the channels
the original does not have much noise but if I need to replace the blue channel with red or both green and blue with red to increase the luminosity I end up with a very noisy sky
then when I sharpen its worse

This is a harsh adjustment for this image and but I just used it to show what is happening

I can fix it but I just want to make sure its not something I am causing either in my camera or post processing

I am happy to be told I am overreacting and being too fussy

thanks for your time
Julie

any more word on an advanced curvemeister class? No pressure just imterested

 

[imported_ganna]

Julie, I think using a mask and work selectively may be a solution. I often do selective sharpening through a mask

[imported_julie]

thanks ganna

that's what I have been doing and it works well
Are you able to use a curvemeister mask or do you use the mask in photoshop
sometimes I just copy the sky and paste into another layer

Julie

[imported_ganna]

Yes, I do the same :)

[ggroess]

Try switching the image to LAB mode in PS and Gaussian blurring the B channel a bit more than the A channel and see if you get a better result? 

If it is color noise that can be an effective way to handle it sometimes...
Greg