Digital BW, The Print

hi Steve -

I don't work with Capture One so I can't help on that specifically. But
here is a trick that may prove helpful, probably in combination with
other corrective measures you may already have found.

Before you convert to b&w, use Select Color Range to select the blue
sky. Save this selection as an alpha-channel mask. 

Then when you're editing your b&w image, use Load Selection to reload
that mask. This will re-select the sky. While the sky is selected, add a
curves adjustment layer (the selection will become the layer mask). By
manipulating the sky curve, you'll be able to adjust the tone of the sky
quite precisely -- without changing the sand dunes. 

You'll want to do this in 16 bit mode. And if you do see any dithering
in the sky, a little Gaussian blur (while the sky is selected, of
course) will take care of it. Also, note that reloading the sky mask
will not work if you've cropped or resized the image since you saved it.

Hope this helps,
Richard Wolfson
Fine Art Photographer & Digital Imaging Consultant

 

> -----Original Message-----
> From: Steve Kale [mailto:stevekale@...] 
> Sent: Monday, January 10, 2005 1:33 PM
> To: DigitalBlackandWhiteThePrint@yahoogroups.com
> Subject: [Digital BW] Posterization in red channel
> 
> 
> 
> Hi. I am just working up an image from my new digital camera 
> and have come across something that is puzzling me.  The 
> colour image looks great - no posterization and no apparent 
> clipping in any channel.  From the RAW file I used Capture 
> One Pro with high contrast setting and simply slid the RGB 
> black point slider up to the left of the red histogram and 
> then processed (no other adjustments).  In PS, I then used 
> the split channels technique to work up a B&W version.  The 
> image is of a sand dune against a dark
> (blue) sky.  My problem is that the red channel appears (on 
> screen - I have not printed it
> yet) to be posterized in the sky.  I want to use the red 
> channel because it is giving me the dark sky.  Any ideas as 
> to why this would be?  I can go back to the original RAW file 
> if need be. 
> 
> Steve 
> 
> (I have ordered the 3 channels as follows:  base Green at 
> 100%, red on top at 90%, then blue with pinlight for extra 
> contrast on top at 40%.  Although the posterization is 
> evident just looking at the red channel.)
>