Using the Mask feature of Photoshop for better exposure

Monarchs of Colchuck Lake

Marc Dilley of Marc Dilley Photography showed me a technique in Photoshop which is advanced for me, easy for him.  Here is how Marc uses the Mask feature.

(Marc) I am using this image of Colchuck Lake in the Cascade Mountains of Washington to discuss some basic elements of exposure, composition and how those two field skills relate to processing an exposure (or, in this case, two exposures).

Let's begin with exposure. Note that every element of this image is properly exposed: you can make out detail in the mid tones such as the boulders, trees and driftwood but also in the brightest parts of the sky and the shadowy areas. If you have shot much in the mountain environment, even with a top quality full-frame DSLR, you know that blocked shadows and clipped highlights are unavoidable. The dynamic range of the scene, that is, the brightness range from the darkest shadows to the brightest highlights, is too great for the sensor to record. If you expose to get detail in the shadows then the highlights will be hopelessly overexposed in a white, confused mass. You have all seen this - with their tiny sensors, phone cameras are quite susceptible to this (there is a direct correlation between sensor size, or more precisely pixel size, and image quality). Conversely, if your exposure is made for detail in the highlight areas of the scene, then the shadows and most likely the dark mid tones will be black or disturbingly dark.

Unlike the old film days, with digital photography there is a way to mitigate this issue. As above, make two exposures, one correctly exposing the highlights and one correctly exposing the shadows. Note that these two exposures absolutely must be shot with a tripod, or on a boulder. Now, here is where you need a good working knowledge of Adobe Photoshop. I am not aware of any other photo processing software that would allow a photographer to manipulate exposures in the following popular and well regarded technique, and that includes Adobe Lightroom.

One more digression before we move along. If your camera will output images in Raw, you should take advantage of this feature. I'll leave a talk on Raw for another time but suffice it to say that shooting in Raw will give you unmatched potential over jpeg, period. Another absolute: get on the website and sign up for Lightroom or Photoshop. It will cost you about $25/month and if you are serious about photography it will be the best $$ you will ever spend. There are good reasons why Photoshop is the gold standard for all photo artists - don't shop around for competing software. The learning curve is steep, but You Tube has hundreds of helpful videos; if you seek truly professional instruction look up

On to the technique:  Photoshop allows you to "stack" distinct exposures -one on top of another- in the same work file. Just like a stack of cards, only the exposure on the top can be seen. But... Photoshop provides a neat and incredibly powerful structure that rides along with each exposure - the Mask. The Mask controls how much of it's respective exposure will be visible. A pure white mask allows all the exposure to be seen; a pure black hides all the exposure; a neutral 50% gray mask makes the exposure ghostly half-transparent. After I stacked the cloud exposure (the darker shot where the bright highlights were exposed properly) on top of the land/water/cliff exposure, I took my paintbrush tool and carefully painted black pigment over the land portions of the cloud exposure mask, hiding all of it's darker areas and revealing the well exposed parts of the land/water/cliff exposure below. I then painted back and forth with various shades of gray to adjust the blend then moved on to contrast and color adjustments, finishing off with dust removal, some minor chroma and noise.

A final note: some of you may use or may have heard of the HDR technique. HDR, or High Dynamic Range photography, is to some degree or another an automated process whereby three or more exposures (in register) are shunted into HDR software and pops out a fully cooked image with good tonality in all areas of the scene. HDR images have a unique look to them and you either like it or you don't. They are distinct enough from traditionally made images that most photo forums place HDR images in their own category. HDR has it's place but for full creative control you must jump in and learn to use layers.