Quick Mask is a most effective selection tool and one that's often overlooked. This may in part be due to its location at the vase of the Tool Bar and its less-than-obvious appearance.

Quick Mask is a selection method based upon painting over an area of the image that is to be either 'protected' (masked) or 'active' (with the 'outside area being the 'mask').

Quick Mask can be used as a tool to initially define the 'selection' required or to refine an already 'active selection' by adding and/or subtracting from that selection.

Quick Mask is particularly effective in helping to make a 'selection' where the area to be defined is difficult and fiddly. Quick mask also responds to the softness and hardness of the brush setting thus offering a ready 'feathered edge' if needed.

All will be revealed.

Taking the image of spanners below as our working example: The old 'Fordson' spanner is a difficult shape to select with speed using the lasso or polygon lasso tools. (Yes, the 'Pen / Path Tool' would be an alternative but this isn't the exercise).

For this demonstration, I'm going to concentrate on selecting the area immediately around the small snail motif and swapping the colour in this section to green, leaving the snail its original orange. Quick Mask is ideal for this as the difficult parts around the snail can easily be dealt with.

Begin by locating the Quick mask Tool. It will be at the base of the Tool Bar but depending upon which version of Photoshop you are running, it will be either two icons side-by-side or (as in later versions) a single icon. It really doesn't matter as they both do the same job.

The screen-grabs below illustrate the differences.

Above: Earlier versions, the Quick Mask icon near the base of the Tool Bar
(r.h. icon, Quick Mask 'On'; l.h. icon Quick mask 'Off')

Above: Later versions, the Quick Mask icon at the base of the Tool Bar