 Component plane

A component plane stores samples of one component of an image separately from its other components. A three-plane RGB color model layout can hold a red array, a green array and a blue array, each indexed by image location. Intel's planar-format table records this arrangement explicitly.^[ref] A component plane stores component samples, which can occupy several bits; a bit plane stores only one bit position from each sample.

For an original $2\times 2$ image, takeAt row one, column zero, using zero-based indices, the pixel is $(70,80,90)$. If each component uses one byte and row-major order, the active red bytes are 10 40 70 100. A routine that changes the red component plane can leave the green and blue arrays untouched.

The three active arrays contain $3\cdot 2\cdot 2=12$ bytes. With a separately declared four-byte framebuffer stride for each plane's row, storage instead occupies $3\cdot 2\cdot 4=24$ bytes, including padding. The image values are unchanged. A plane's dimensions, base address and row stride are therefore distinct parts of its layout description.

Other colour representations need not have three equal-sized, separate component arrays. Intel's table includes formats with differently sized planes and formats that interleave two colour components in one plane.^[ref] A semiplanar pixel format combines a separate plane with such an interleaved plane. Thus an API's memory-plane count alone need not equal the number of colour components. A component plane is a statement about data organization, separate from the color space that interprets its numerical samples.