layers

lay·er

L0078500 (lā′ər)n.1. a. One that lays: a tile layer.b. A hen kept for laying eggs.2. a. A single thickness of a material covering a surface or forming an overlying part or segment: a layer of dust on the windowsill; a cake with four layers.b. A usually horizontal deposit or expanse; a stratum: layers of sedimentary rock; a layer of warm air.c. A depth or level: a poem with several layers of meaning.3. Botany A stem that is covered with soil for rooting while still part of the living plant.4. An item of clothing worn over or under another.v. lay·ered, lay·er·ing, lay·ers v.tr.1. To divide or form into layers: layered gravel and charcoal to make a filter.2. To cut (hair) into different, usually overlapping lengths.3. Botany To propagate (a plant) by means of a layer.4. To wear (clothing) in layers.v.intr.1. To form or come apart as layers.2. Botany To take root as a result of layering.

layers

ply - From Latin plicare, "fold," a thickness or any of the layers of a multilayer material, such as plywood.
disk - The layers of cartilage and pulp between vertebrae.
Neapolitan ice cream - Gets its name from its layers resembling the Italian flag.
delaminate - To separate into layers.

layers

Separate "drawing boards" or "canvasses" in a drawing, CAD or image editing program that are overlaid one on top of the other to complete the picture. Layers provide greater control over the illustration or image and offer different functions depending on the application. For the differences in graphics applications, see graphics.

Drawing Programs (Vector Graphics)
Computer-aided design (CAD) programs were the first software to provide layers, and advanced illustration programs followed suit. Graphic objects can be placed in separate layers on top of or below other layers, enabling related objects to be worked on as a group without affecting the rest of the drawing. See graphics and CAD.

Imaging Programs (Bitmapped Graphics)
Layers are available only in advanced imaging programs such as Photoshop, otherwise all editing is done on a single plane. In single-layer paint and image editing software, when a graphic object is added, it replaces the pixels that occupied that same space. Consequently, if the object is removed, it leaves blank space in its stead.

However, in a layered imaging program, objects are placed in separate layers and can be freely moved under and over each other. Objects can always be added, and any object can be removed or changed without affecting the others. The final result is the composite of all layers, which can be "flattened" into one layer for conversion into a JPEG, BMP, GIF or other bitmapped file format. The original image can be maintained in its layered format for future modifications, such as in Photoshop's proprietary PSD format.

Layers in Photoshop

The bitmap image above is built in 23 layers plus a background layer, enabling the individual elements to be moved independently of the others. The Photoshop layer window (below) shows the layers. The red arrow is pointing to the view option (the "eye") in the chip shadow layer. Clicking the eye toggles the layer between visible and invisible.