The Shadow/highlight tool was introduced with Photoshop CS,
and I consider it to be one of the most valuable tools to use
if you want to get the best out of your images. It gives you the
ability to bring out details in the shadows and highlights in
a very controllable way.
Although it does not replace the need for fill-in flash, it does
go some way in that direction, as it can lighten and bring out
shadow detail - such as when shooting against the light without
It can be used to help rescue a badly under-exposed image, can
retrieve highlight detail in an over-exposed or over-flashed image,
but more importantly, it can actually improve a properly exposed
image by lightening up very dark areas of the image and toning-down
very bright areas.
I could have given a spectacular demonstration of what it can
do on improving a really bad image, but instead I have chosen
to give you a more subtle, real-world example below with this
After shadow/highlight adjustment
Look at the barn owl's eyes - see how the dark areas have been
lightened and give more life to them ? Now look at the detail
around the beak and breast feathers - the highlights have been
toned down to reveal more highlight detail. Although both images
have been sharpened identically, the adjusted image looks sharper
- as there is more apparent detail for the USM filter to work
with. Finally, notice that the wing of the bird (with no important
shadow or highlight detail) remains totally unchanged - a good
How to use the Shadow/Highlight tool
I have read many technical descriptions on how to use this tool,
but my eyes soon glazed over, and I still struggle to understand
what the experts will tell you the various sliders are doing with
the pixels. What I can offer instead, is a foolproof procedure
for adjusting any image, with a demonstration of what each slider
does in a practical worked example. So here goes....
Open up an image to work on. To practice using the sliders, I
recommend using a picture of something pretty black (a jackdaw
in my first example) and another containing a lot of white (a
spotted flycatcher with white breast feathers on my second example).
I like to work on a 16bit TIFF image which has been converted
from a RAW file, and has already had level adjustments made, but
no sharpening, resizing etc.
To access the Shadow/highlight tool, click on Image>adjustments>shadow/highlight.
When you open the tool for the first time, the image will change
radically according to Photoshop's default settings - which will
probably be totally inappropriate for your image. Ensure that
the "Preview" box is checked - so you will see the changes
you make actually happen in real-time. Also tick the "Show
more options" button - as we need to gain access to the "Amount,
Tonal Width and Radius" sliders for both highlight and shadows.
1.0 Working on the shadow areas
There are a lot of sliders, and they are all inter-dependant.
Move one and it effects all the others seemingly. What we need
is a way through this jungle - a foolproof method - and here it
is... read on !
We are first going to see what the effect of moving the shadow
sliders is, so we need to turn off the effect of the others. To
Set both amount sliders to 0
Set both Tonal Width sliders to 0
Set both radius sliders to 50%. I will explain more later - but
trust me on this for now.
Here is the image of the jackdaw viewed on the screen at 100%
(click on the magnifying glass tool and select actual pixels from
the top toolbar). All the sliders have been set as described above.
In the next screenshot, I have increased the Shadows "Amount"
slider to around 45%. Notice how the shadows have lightened considerably
- revealing more detail, but have not affected the light blue
background behind the bird ?
|If I slide the slider way over to 100% , the darkest feathers
have lightened to a grey tone! The amount slider is pretty
self-explanatory then. When we come to the highlight amount
slider later on, it works in the same way but in reverse -
as it darkens the highlights as the Amount is increased.
I got bored looking at our jackdaw's front, so lets move up to
his head. I set all the sliders back to my starting values again.
Incidentally, you can save these as your default settings by clicking
the "Save as default" button - to prevent having to
reset them each time.
|Next, I have moved the amount slider to 75%. Notice that
the darkest parts of the bird between
the base of the bill and the eye have lightened and the ruff
of feathers at it's throat look far more detailed now ? Now,
this is much as before, so now we will turn our attention
to the dreaded "Tonal Width" slider.
|In simple terms, if the slider is set to zero then only
the very darkest pixels will be lightened. As the slider is
moved to the right, slightly lighter pixels than the very
darkest ones are also lightened - and so on, until midtone
pixels are being selected and lightened too. To put it another
way - a low Tonal Width value selects the darker pixels only,
a high Tonal Width value will include progressively more lighter-toned
pixels in the selection to be adjusted by the Amount slider.
In the example below, I have kept the same Amount settings
as used in the previous image, but increased the Tonal Width
to 24%. Notice how far more midtone grey areas have now been
lightened too? I have overdone things intentionally a little
to illustrate my point.
|Finally we come to the mysterious Radius slider.You will
remember that we preset this to a value of 50 pixels, which
is in the right ballpark for most camera images of around
6-10 megapixels - as it is image size dependant. The slider
should be tweaked for each image, and you will find that if
you set it too low (try it at zero) you will notice a blurring
of detail. The slider needs to be set according to how large
the dark (or light) areas are. As you move it around, you
will notice a definite "sweet spot" where image
detail is maximised, and the midtone contrast remains unaffected
In the screenshot below, I have reduced the "Amount"
to a more sensible 26%. adjusted the "Tonal Width"
to 5% to select the darker tones only, and tweaked the Radius
to the sweet spot - which came out at about 33 pixels. A subtle,
but definite improvement on the starting image I think.
|Finally below, I have demonstrated what happens if you set
the Radius slider too low.
Compare it to the (good) screenshot above, and you will notice
how the feathers on the throat
and the back of the head are far less sharply defined and
the image has gone "flat" due to lack of
2.0 Working on the highlight areas
Once you are satisfied with your shadow settings, you
can move on to the highlights. If you only want
to address the highlights, set the shadows amount slider to zero.
Here is the picture of a spotted flycatcher. It
should be said that the tool can not retrieve details in pixels
that have completely burnt out to white, but it can often retrieve
more detail than you would have probably believed possible.
The procedure is just the same as for the shadows, so starting
at the same settings as for the shadows, set the Highlight sliders
to: Amount 0%, Tonal Width 0%, Radius 50px settings.
Now move the amount slider to the right. As the Tonal width is
set to zero, only the brightest pixels will be selected this time.
Watch the white breast feathers darken and gain in highlight detail.
In the image below, I went on to adjust the Tonal Width to just
3% ( to select just the very lightest pixels that I wanted to
darken) and finally tweaked the Radius to the "hotspot"
of 50 pixels.
|I realise that it is difficult to see these differences
on these very low low-resolution screenshot examples,
so here are a couple of 100% crops which better demonstrate
the kind of improvements that I am seeing on my computer
After highlight adjustment
Finally, you may have noticed a couple more sliders called "Color
Correction" and "Midtone Contrast." These may be
used if you feel that the colour or midtone has shifted a little
as a result of making your adjustments. I rarely use the Color
slider, but sometimes images benefit from a bit more contrast,
as by lightening shadows and darkening highlights simultaneously,
you are effectively lowering the overall contrast. Conversely
I have also been known to intentionally lower contrast in some
images in this way that were taken in harsh light.
I strongly recommend you try using the shadow/highlight tool -
I think you will be amazed at how effective it can be.