Layer
An image can have just one layer or it can have multiple layers. Only the current active layer can be edited. Individual layers can contain layer effects. They can be restacked, moved, and renamed. You can also choose blending options and masks for them. A layer can be transparent when it has no pixels.
Adjustment Layer
Modifications to an adjustment layer do not alter the actual pixels until the layers are merged. This is useful for adjusting hue, saturation, color balance, levels, etc. You can have many adjustment layers and turn them on and off as needed.
Pixels
Pixels are dots that are used to display a bitmapped image on a computer screen.
Vector
Vector elements are point based and mathematically calculated lines. They are scalable without losing quality, unlike pixel/raster based images. Photoshop has the ability to create vector paths, shapes, and type.
Foreground and background colors
The foreground color is applied when you are using a painting tool, creating type, or a stroke. Selections can be filled with either foreground or background color. These are also used in the process of creating quick Masks and additional Photoshop tasks.
Selection
An area of an image that is isolated with ³marching ants² marquee. The unselected area is protected from editing. A selection can be made with: the lasso, the marquee, converting a path to a selection, or loading an alpha channel as a selection.
Masking
Protects part of an image, while enabling the rest of the image to disappear. It acts as a cookie cutter, cutting out a shape from an image. Masks are saved to the channels palette as alpha channels. They can then be loaded as selections, saved as paths, and reused to cut out with the selection shape again and again.
Preset
Saved type, gradient, pattern, shape, style, or tool setting
History
Every change that
is made to an image is saved on the History Palette as a separate state. While
an image is still open, it can be reverted back to a prior state with this
palette.
Layer Effects
Ten effects that can be applied to any layer and are fully editable and removable. A style is a saved effect or combination of multiple effects. Ex. Drop shadow, inner glow, Gradient overlay, stroke, etc.
Pixel dimensions, resolution
The pixel dimension value is the number of pixels and image contains. The resolution is the density of pixels per unit of measure (usually per inch). The two are integrally related.
Brightness, hue, saturation
Brightness is a colorıs lightness. Hue is the wavelength of light that gives the color its name. ex. Red. . Saturation is the degree of purity, or amount of gray in a color.