Pixelation

Reducing an image in size can be done very effectively but the same cannot be said when attempting to enlarge an image. This is because as an image is enlarged the square edges of the pixels become more noticeable.

As a result the image loses clarity and the divers look more like Lego figures.

This loss of quality and squarish tone to the image is known as pixelation and should always be avoided.

Taking your shots on the highest quality image size will always allow you more latitude for later manipulation of the shot.