Image Masking, 1

A Key Element of Effective Post-processing

This is the first of a series on using masks in post-processing. The masks are created in Capture NX2 which is my image editing software of choice – and the ease of creating masks is a large part of the reason why it’s my choice. Photoshop users might be interested in the relative ease of creating and using masks in NX2 as compared to Photoshop (full Photoshop is required as masks aren’t available in Elements).
What is an image editing mask?
No, not this¬† kind (my “Gravatar” – globally recognized avatar), but the following type (made in 1 second; Photoshop would take how long??)
( Click any image to enlarge)
which is a gray scale image

used to control where and how strongly various image editing adjustments are applied.

The above mask was made for (from) the following image by selecting the trees in the upper center. The selection was done simply by clicking in the trees (enlarge the mask to see the “control point” that was created where I clicked).

In a typical mask, the editing adjustment is applied in full to white areas and not at all to black (and, you guessed it, to varying degrees to other areas depending on their gray tone). So in this case the trees which I selected (actually I selected them in an inverse sense – I asked that they NOT be affected by the adjustment) will remain untouched by the change I’m about to make. For illustration – here’s the corresponding mask if I had want the trees to be impacted but NOT the other parts of the image. Remember – white parts of the mask allow the full force of the adjustment to be applied.

Let’s take a look at how the target image is affected by using these masks. The adjustment I’ll use is one that converts a color image to black and white (done to show clearly what is changed and how much).
Applying the first mask yields this image, which is a “selective coloring” effect

Applying the second mask gives us this image with B&W trees

I’ll wrap up this first masking post with a more sophisticated version of the first mask. This one brings in more of the tree reflections than we saw in the first one, adds the foreground golden grasses to the “selective coloring” along with the green trees. If you have experience with masking, imagine the effort to mask the grass – piece of cake here with a few clicks.

One more time – the dark areas of the mask “hold back” the adjustment. The adjustment in this case is a conversion to B&W. We see that the trees and foreground grasses were not “adjusted”.
For the 2nd installment of this masking series go here.

0 thoughts on “Image Masking, 1”

  1. Thanks, Ed.
    ‘Bout time I rolled up my sleeves and learned this useful post-processing technique! Sort of been afraid to tackle masking — seemed somewhat arcane, but your explaination makes sense.
    Keep it up.

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