Pixel and Planar Image Formats

Data storage for an image can be pixel-oriented or planar-oriented (planar). For images in pixel order, all channel values for each pixel are clustered and stored consecutively. Their layout depends on the color model and downsampling scheme.

Table “Pixel-Order Image Formats” lists all pixel-order image formats that are supported by the oneIPL color conversion functions and shows the corresponding channel values order (here, group of underlined symbols represents one pixel and symbol A denotes alpha-channel value). The last column of this table gives an example of an oneIPL color conversion function that uses the respective image format. oneIPL supports only 3- and 4-channel pixel formats. Gray-scale images are represented using pixel format with one component.

Format	Number of Channels	Channel Values Order
layouts::plane	1	P0 P1 P2 P3 P4 …
layouts::channel3 (RGB)	3	R0 G0 B0 R1 G1 B1 R2 G2 B2
layouts::channel4 (RGBA)	4	R0 G0 B0 A0 R1 G1 B1 A1
layouts::channel3 (BGR)	3	B0 G0 R0 B1 G1 R1 B2 G2 R2
layouts::channel4 (BGRA)	4	B0 G0 R0 A0 B1 G1 R1 A1

Planar image formats supported by the oneIPL color conversion functions are listed in Table “Planar Image Formats” along with examples of the oneIPL functions using that format. Planes layout and their relative sizes are shown in Figure “Plane Size and Layout: 3-planes Images” and Figure “Plane Size and Layout: 2-planes Images”. oneIPL supports only RGP and 4:2:0 subsampling formats in some functions.

Format	Number of Planes	Planes Layout 1	Planes Layout 2	Planes Layout 3	Further Explanation
layouts::plane3	3	R	G	B	see Figure below, a
layout::sub420	3	Y	U	V	see Figure below, d
layout::sub420i	2	Y	UV		see Figure below for 2-planes images, b