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Dive Photo Guide

Correcting Tonal Problems

By Doug Sloss

Getting the light right when shooting underwater can be quite a challenge.  Luckily, Photoshop offers numerous ways to fine tune minor exposure problems and correct tonal variations in a subject when needed.  Let's look at one method now. Here's a photo of a solitary sea fan taken during the Digital Shootout this past June in Little Cayman.

The image before tonal correction


While the fan is reasonably exposed, too much strobe power overexposed the subject.  As a result, the fan loses detail lacks the degree of density I remembered it having at the moment of capture. No problem.  With a few minor adjustments in post, we can make this sea fan (and many other marine subjects) look much better on screen and in print. Instead of using the Dodge and Burn tools, which offer limited flexibility and can destroy detail in your image, try using this simple and quick way to improve a photo with similar issues.


The image after tonal correction


Start by creating a digital canvas to non-destructively work on your shots.  Use it to fix exposure problems , bring out detail in an image, create density, and emphasize features that sometimes lay hidden. This is definitely a technique shooters of all levels can use to create the best image possible.

Here's how to set it up.

Navigate to the Layers panel, hold down the Alt/Option key and click on the New Layer icon at the bottom.  In the New Layer dialog name the layer Dodge and Burn, choose Soft Light from the Mode menu and check the "Fill with Soft-Light-neutral color option to fill the layer with 50% gray and click OK.  This creates a new layer inside the Layers panel and assigns a descriptive name to it, to help keep you organized when working on a multi-layered document.  Notice the layer's thumbnail is filled with gray but because the blend mode is set to Soft Light, Photoshop ignores this neutral 50% gray keeping your image looking the same for the moment.  With this new layer you now have a digital canvas that will allow you to non-destructively change the tonal values in your photo and "tweak the light" in your favor.



Next, press "D" on the keyboard to quickly reset Photoshop's toolbox colors to black and white then tap "B" to access the Brush tool.

In the Options bar leave the Mode set to Normal, the Flow at 100%, and make sure you are working with a soft-edge brush (50% or lower.)  Brush hardness will vary depending on what you are trying to enhance but for many underwater (and topside) images you'll find a hardness setting of 0% will help painting edits blend in easier and makes enhancements look more believable and realistic.

Finally, lower the Brush Opacity before you begin painting.  Bring it way down, somewhere between 5-20%.  This allows you to apply tonal corrections a little at a time building up the effects using subsequent brush strokes.  A lowered opacity will also give you more control as you lay down your edits.  For this image the brush opacity was initially set at 10%.  With Photoshop properly set to dodge and/or burn areas in your image, simply decide what you need to work on.




In this photo, while the sea fan is exposed fairly well, I want to darken (burn) it in order to bring out some hidden detail and add depth back into this subject. To do that, I paint over it with a black brush. If I had to lighten (dodge) some areas, I would paint using a white brush. By lowering the brush opacity I was able to darken the image little by little and build up the desired effects over time allowing precise control over the enhancement process.





Here are a few brush tips to help you along while you dodge and burn your own images.

  • Use the right and left bracket keys to increase or decrease the size of the brush respectively.
  • Use the number keys to quickly change brush opacity. 1-9 = 10%-90% 0 = 100%  Quickly tap two numbers in succession for additional opacities (e.g. 2,5, for 25%)
  • To cover areas in a photo evenly, use a single brush stroke to darken or lighten the region by pressing and holding down the mouse while you paint. Paint over areas more than once to increase the effect and vary the brush opacity if needed to achieve your desired results.
  • Press the letter "X" to quickly switch between the black and white brush
  • To correct mistakes, use the History panel to revert to an earlier image state, or set your Foreground color to 50% gray, raise the brush opacity to 100% and paint over any area you would like to erase and start again using a black or white brush.
  • Lowering the actual Layer opacity can also fine-tune the overall effect of your brush work too.

While there are a handful of other ways to effectively dodge and burn regions in a photo, a single Soft Light layer is flexible and quick enough for most of the dodging/burning effects you typically want to create in your underwater images.  And remember, exposure correction with a digital canvas gives you plenty of control, protects your original file and allows you to go back and revisit your edits in the future if needed.  So get creative and regain control over your tonal adjustments.  Great photos are just a few brushstrokes away.
About the author

Doug Sloss is an internationally published photographer and writer specializing in the marine environment. He is also producer of a handful of educational DVDs, including his latest release Adobe Photoshop CS4 for the Underwater Photographer. Learn more at www.underwaterphotoshop.com



Khaled Al-habib
Nov 30, 2011 4:32 AM
Khaled Al-habib wrote:
many thanks
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