The Basics of Masks in an Image - Part I
Masks allow you to isolate areas of an image from colour changes or filter effects applied to the rest of the image.
Unlike real-life masks, digital types are very versatile: you can, for example, alter a mask's opacity so that its effects taper off allowing you to see more or less clearly through it.
Using image-manipulation software you can alter a mask until you are satisfied with it and then save it for reuse.
When you do so, you create what are known as "alpha channels", which can be converted back to selections.
Technically, masks are 8-bit greyscale channels - just like the channels representing the colours - so you can edit them using the usual array of painting and editing tools.
If your software does not offer masks, do not worry - it is possible to carry out a good deal of work by the use of selections.
But remember that selections are inclusive - they show what will be included in a change; masks work the opposite way, by excluding pixels from an applied effect.
Software takes two approaches to creating masks.
First is Photoshop's Quick-mask, which gives direct control and allows you to see the effect of any transitional zones.
Or, you can create a selection that is turned into a mask.
This is quick, but transitional zones cannot be assessed.
In Photoshop and Photoshop Elements you hit the Q key to enter Quick-mask mode.
You then paint on the layer and hit Q again to exit, but in the process, you turn the painted area into a selection.
You can also invert your selection (select the pixels you did not first select) - sometimes it is easier to select an area such as bright sky behind a silhouette by selecting the silhouette and then inverting the selection.
You then turn the selection into a mask by adding a layer mask.
Unlike real-life masks, digital types are very versatile: you can, for example, alter a mask's opacity so that its effects taper off allowing you to see more or less clearly through it.
Using image-manipulation software you can alter a mask until you are satisfied with it and then save it for reuse.
When you do so, you create what are known as "alpha channels", which can be converted back to selections.
Technically, masks are 8-bit greyscale channels - just like the channels representing the colours - so you can edit them using the usual array of painting and editing tools.
If your software does not offer masks, do not worry - it is possible to carry out a good deal of work by the use of selections.
But remember that selections are inclusive - they show what will be included in a change; masks work the opposite way, by excluding pixels from an applied effect.
Software takes two approaches to creating masks.
First is Photoshop's Quick-mask, which gives direct control and allows you to see the effect of any transitional zones.
Or, you can create a selection that is turned into a mask.
This is quick, but transitional zones cannot be assessed.
In Photoshop and Photoshop Elements you hit the Q key to enter Quick-mask mode.
You then paint on the layer and hit Q again to exit, but in the process, you turn the painted area into a selection.
You can also invert your selection (select the pixels you did not first select) - sometimes it is easier to select an area such as bright sky behind a silhouette by selecting the silhouette and then inverting the selection.
You then turn the selection into a mask by adding a layer mask.
