Understanding Layers and Channels in Digital Photography
The "layers" metaphor is fundamental to many software applications, such as desktop publishing, video animation, and digital photography.
The idea is that images are "laid" on top of each other, though the order is interchangeable.
Think of layers as a stack of acetate sheets with images; where the layer is transparent, you see through to the one below.
However, not all software layers have the same resolution, start with the same number of channels, or have the same image mode.
The final image depends on how layers blend or merge when they are "flattened", or combined, for final output.
Before then, however, they allow you to make changes without altering the original data, while each remains independent of the others.
Colour as layers A point to grasp is that the basic colour image is comprised of red, green, and blue layers - normally called channels.
In essence, the terms "layers" and "channels" are interchangeable.
Masks, too, are channels, as they work with a layer to affect the appearance of an underlying layer.
By analogy, if you see a face through a layer of misted glass it looks soft or diffused.
Now, if you polish part of the layer, the portion of face lying directly under the polished area becomes clear, without the distortions caused by other parts of the glass.
So the glass is a layer over the underlying layer - the face - and by doing something to part _ of it, but not the whole, you have applied a mask, which is in effect another layer.
Using layers The main use for layers (also known as "objects" or "floaters" in some applications) is to arrange composite images - those made up of two or more separately obtained images.
You can place images on top of one another - varying the order in which they he; duplicate smaller images and place them around the canvas to create a new image; or change the size of the individual components or distort them at will.
At the same time, the ways in which one layer interacts or blends with the underlying layer - known as the blend modes - can also be altered.
Finally, you can control the transparency or opacity of the layers, too - from high opacity for full effect (or low transparency), to barely visible, when you set a high transparency.
The idea is that images are "laid" on top of each other, though the order is interchangeable.
Think of layers as a stack of acetate sheets with images; where the layer is transparent, you see through to the one below.
However, not all software layers have the same resolution, start with the same number of channels, or have the same image mode.
The final image depends on how layers blend or merge when they are "flattened", or combined, for final output.
Before then, however, they allow you to make changes without altering the original data, while each remains independent of the others.
Colour as layers A point to grasp is that the basic colour image is comprised of red, green, and blue layers - normally called channels.
In essence, the terms "layers" and "channels" are interchangeable.
Masks, too, are channels, as they work with a layer to affect the appearance of an underlying layer.
By analogy, if you see a face through a layer of misted glass it looks soft or diffused.
Now, if you polish part of the layer, the portion of face lying directly under the polished area becomes clear, without the distortions caused by other parts of the glass.
So the glass is a layer over the underlying layer - the face - and by doing something to part _ of it, but not the whole, you have applied a mask, which is in effect another layer.
Using layers The main use for layers (also known as "objects" or "floaters" in some applications) is to arrange composite images - those made up of two or more separately obtained images.
You can place images on top of one another - varying the order in which they he; duplicate smaller images and place them around the canvas to create a new image; or change the size of the individual components or distort them at will.
At the same time, the ways in which one layer interacts or blends with the underlying layer - known as the blend modes - can also be altered.
Finally, you can control the transparency or opacity of the layers, too - from high opacity for full effect (or low transparency), to barely visible, when you set a high transparency.
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