The first picture where masking was used is seen in the two pictures below. I basically utilized masks to take the original picture and make it nighttime. I created a mask over the original photo in the above portion and made it transparent and then selected the water and utilized a mask to give it a light gradient to give the impression that there was a reflection of nighttime. I then utilized the blur tool to subtly darken portions of the photograph including the rock and the trees.
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After:
The second picture where masking was used is seen in the two pictures below. I utilized a mask after selection to place an american flag in the background of a picture of me to simulate a picture that a presidential candidate might take.
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After: