Shadows masking technique


At 3:52 AM -0700 12/15/05, G.D.Speer wrote:
A little tweak with the shadow and highlight tool?

Oh no! I stay as far away from that as I possibly can. If you're not
extremely careful with that tool you can easily ruin your pictures.
It seems a little extra contrast and detail appeared in the rock face
and the water.

Yes, that is what I worked on. I did several rounds of selective
sharpening. Different portions of the image required different levels
of sharpening in addition to the overall sharpening I did previously.
This helped pop the detail in the rock face, river banks and trees.



I also use a shadows masking technique Bob taught me to separate
different portions of the image. You duplicate the image then after
flattening the duplicate you look at the individual red, green & blue
channels. You look for the channel which is darkest in the area you
are interested in working on separately from the rest of the image.
With that channel selected you convert to grayscale, discarding the
other 2 channels. Now you do a levels adjustment directly to the
channel, do not use an adjustment layer, and tweak it to make it more
contrasty bringing down the highlight slider and bringing up the
shadows slider so both ends of the histogram are clipped. You also
adjust the midtones slider to taste. This is the hard part and it
takes some practice to learn how to make the adjustments. What you
are doing is creating a mask directly from the image rather than
trying to paint one.

When you get the levels the way you want them you switch back to the
original image's Background layer (or if you Sharpen to a duplicate
layer, that one) then do a Load Selected and select the grayscale
channel from the duplicate image with the Inverse option turned on.
Now Command-J to create a new layer from the selected area. I name it
Shadows mask and create a Group for it and the adjustments I want to
have made to that portion of the image. Move that layer/group to the
top of the stack and any adjustment layers you add from this point on
you link to that new layer so the adjustments affect only that
portion of the image. Of course you can still add layers to make
additional adjustments to the overall image if needed, just don't
link them to the shadows mask layer.

This gives you greater control over making changes to individual
portions of the image and when done right adds a level of
dimensionality which might otherwise be missing. It makes things pop.

This image has 16 layers including the Background which is turned off
but kept for if I decide to start over. ;-) I do duplicate the
Background then use the duplicate to do my sharpening. I sometimes
over sharpen things but don't notice it until later adjustments start
bringing it out.
Is the old one still up? - fun to see the before and after.

Here you go:
<http://brianspics.wittybanter.org/Zion/Pages/AngelsLandingBefore&After.html>
Beautiful work as always. The color of the trees just pops and makes
a nice vertical symmetry.
Well done as always.

Thank you Duke. I've been learning quite a bit from Bob since I
started working for him. He's the guy I'm doing the drum scanning and
large format printing with. Here is his site:
<http://www.plateaulight.com>.
I'm off to visit with family for a week. Happy holidays!

The same to you and your family. And everyone else out there - Merry
Christmas and Happy New Year. :-)
--
Brian Lawson

Some feedback on the technique above
I also use a shadows masking technique Bob taught me to separate
different portions of the image. You duplicate the image then after
flattening the duplicate you look at the individual red, green & blue
channels. You look for the channel which is darkest in the area you
are interested in working on separately from the rest of the image.
With that channel selected you convert to grayscale, discarding the
other 2 channels.

The "After" is a great improvement. You'll be a retoucher yet, Brian!
;-)

Just a quick note, though, you can save a few steps by simply dragging
the color channel you want to use as a mask to the "create new channel"
button at the bottom of the layers palette. The new alpha will contain
all of the channel information from all currently visible layers. The
only reason to flatten first is if you have lots of adjustment layers
or unusual blending modes (sometimes the don't "preview" with 100%
correct pixel values).

And there is no need to shy away from the Shadow/ Highlight compression
tool - it's simply a local tonemapping operator. Kind of a Curves tool
mixed with the channel-masking technique, with a low % Unsharp Mask
thrown in for local contrast where you need it. Use small Amount
percentages and a wide Tonal Width and you will see "more natural"
range compression effects. I actually use it for localized saturation
increases by boosting the Color Correction way up, setting the Shadow
and Highlight Amounts to 1-5% and playing with the Tonal Widths. Fun
stuff!

-Mark

Posted: Thu - December 15, 2005 at 03:44 PM          

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