2.5. RGB Formats¶

2.5.1. Description¶

These formats are designed to match the pixel formats of typical PC graphics frame buffers. They occupy 8, 16, 24 or 32 bits per pixel. These are all packed-pixel formats, meaning all the data for a pixel lie next to each other in memory.

RGB Image Formats¶
Identifier	Code	Byte 0 in memory								Byte 1								Byte 2								Byte 3
		7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
`V4L2_PIX_FMT_RGB332`	'RGB1'	r₂	r₁	r₀	g₂	g₁	g₀	b₁	b₀
`V4L2_PIX_FMT_ARGB444`	'AR12'	g₃	g₂	g₁	g₀	b₃	b₂	b₁	b₀	a₃	a₂	a₁	a₀	r₃	r₂	r₁	r₀
`V4L2_PIX_FMT_XRGB444`	'XR12'	g₃	g₂	g₁	g₀	b₃	b₂	b₁	b₀					r₃	r₂	r₁	r₀
`V4L2_PIX_FMT_RGBA444`	'RA12'	b₃	b₂	b₁	b₀	a₃	a₂	a₁	a₀	r₃	r₂	r₁	r₀	g₃	g₂	g₁	g₀
`V4L2_PIX_FMT_RGBX444`	'RX12'	b₃	b₂	b₁	b₀					r₃	r₂	r₁	r₀	g₃	g₂	g₁	g₀
`V4L2_PIX_FMT_ABGR444`	'AB12'	g₃	g₂	g₁	g₀	r₃	r₂	r₁	r₀	a₃	a₂	a₁	a₀	b₃	b₂	b₁	b₀
`V4L2_PIX_FMT_XBGR444`	'XB12'	g₃	g₂	g₁	g₀	r₃	r₂	r₁	r₀					b₃	b₂	b₁	b₀
`V4L2_PIX_FMT_BGRA444`	'BA12'	r₃	r₂	r₁	r₀	a₃	a₂	a₁	a₀	b₃	b₂	b₁	b₀	g₃	g₂	g₁	g₀
`V4L2_PIX_FMT_BGRX444`	'BX12'	r₃	r₂	r₁	r₀					b₃	b₂	b₁	b₀	g₃	g₂	g₁	g₀
`V4L2_PIX_FMT_ARGB555`	'AR15'	g₂	g₁	g₀	b₄	b₃	b₂	b₁	b₀	a	r₄	r₃	r₂	r₁	r₀	g₄	g₃
`V4L2_PIX_FMT_XRGB555`	'XR15'	g₂	g₁	g₀	b₄	b₃	b₂	b₁	b₀		r₄	r₃	r₂	r₁	r₀	g₄	g₃
`V4L2_PIX_FMT_RGBA555`	'RA15'	g₁	g₀	b₄	b₃	b₂	b₁	b₀	a	r₄	r₃	r₂	r₁	r₀	g₄	g₃	g₂
`V4L2_PIX_FMT_RGBX555`	'RX15'	g₁	g₀	b₄	b₃	b₂	b₁	b₀		r₄	r₃	r₂	r₁	r₀	g₄	g₃	g₂
`V4L2_PIX_FMT_ABGR555`	'AB15'	g₂	g₁	g₀	r₄	r₃	r₂	r₁	r₀	a	b₄	b₃	b₂	b₁	b₀	g₄	g₃
`V4L2_PIX_FMT_XBGR555`	'XB15'	g₂	g₁	g₀	r₄	r₃	r₂	r₁	r₀		b₄	b₃	b₂	b₁	b₀	g₄	g₃
`V4L2_PIX_FMT_BGRA555`	'BA15'	g₁	g₀	r₄	r₃	r₂	r₁	r₀	a	b₄	b₃	b₂	b₁	b₀	g₄	g₃	g₂
`V4L2_PIX_FMT_BGRX555`	'BX15'	g₁	g₀	r₄	r₃	r₂	r₁	r₀		b₄	b₃	b₂	b₁	b₀	g₄	g₃	g₂
`V4L2_PIX_FMT_RGB565`	'RGBP'	g₂	g₁	g₀	b₄	b₃	b₂	b₁	b₀	r₄	r₃	r₂	r₁	r₀	g₅	g₄	g₃
`V4L2_PIX_FMT_ARGB555X`	'AR15' \| (1 << 31)	a	r₄	r₃	r₂	r₁	r₀	g₄	g₃	g₂	g₁	g₀	b₄	b₃	b₂	b₁	b₀
`V4L2_PIX_FMT_XRGB555X`	'XR15' \| (1 << 31)		r₄	r₃	r₂	r₁	r₀	g₄	g₃	g₂	g₁	g₀	b₄	b₃	b₂	b₁	b₀
`V4L2_PIX_FMT_RGB565X`	'RGBR'	r₄	r₃	r₂	r₁	r₀	g₅	g₄	g₃	g₂	g₁	g₀	b₄	b₃	b₂	b₁	b₀
`V4L2_PIX_FMT_BGR24`	'BGR3'	b₇	b₆	b₅	b₄	b₃	b₂	b₁	b₀	g₇	g₆	g₅	g₄	g₃	g₂	g₁	g₀	r₇	r₆	r₅	r₄	r₃	r₂	r₁	r₀
`V4L2_PIX_FMT_RGB24`	'RGB3'	r₇	r₆	r₅	r₄	r₃	r₂	r₁	r₀	g₇	g₆	g₅	g₄	g₃	g₂	g₁	g₀	b₇	b₆	b₅	b₄	b₃	b₂	b₁	b₀
`V4L2_PIX_FMT_BGR666`	'BGRH'	b₅	b₄	b₃	b₂	b₁	b₀	g₅	g₄	g₃	g₂	g₁	g₀	r₅	r₄	r₃	r₂	r₁	r₀
`V4L2_PIX_FMT_ABGR32`	'AR24'	b₇	b₆	b₅	b₄	b₃	b₂	b₁	b₀	g₇	g₆	g₅	g₄	g₃	g₂	g₁	g₀	r₇	r₆	r₅	r₄	r₃	r₂	r₁	r₀	a₇	a₆	a₅	a₄	a₃	a₂	a₁	a₀
`V4L2_PIX_FMT_XBGR32`	'XR24'	b₇	b₆	b₅	b₄	b₃	b₂	b₁	b₀	g₇	g₆	g₅	g₄	g₃	g₂	g₁	g₀	r₇	r₆	r₅	r₄	r₃	r₂	r₁	r₀
`V4L2_PIX_FMT_BGRA32`	'RA24'	a₇	a₆	a₅	a₄	a₃	a₂	a₁	a₀	b₇	b₆	b₅	b₄	b₃	b₂	b₁	b₀	g₇	g₆	g₅	g₄	g₃	g₂	g₁	g₀	r₇	r₆	r₅	r₄	r₃	r₂	r₁	r₀
`V4L2_PIX_FMT_BGRX32`	'RX24'									b₇	b₆	b₅	b₄	b₃	b₂	b₁	b₀	g₇	g₆	g₅	g₄	g₃	g₂	g₁	g₀	r₇	r₆	r₅	r₄	r₃	r₂	r₁	r₀
`V4L2_PIX_FMT_RGBA32`	'AB24'	r₇	r₆	r₅	r₄	r₃	r₂	r₁	r₀	g₇	g₆	g₅	g₄	g₃	g₂	g₁	g₀	b₇	b₆	b₅	b₄	b₃	b₂	b₁	b₀	a₇	a₆	a₅	a₄	a₃	a₂	a₁	a₀
`V4L2_PIX_FMT_RGBX32`	'XB24'	r₇	r₆	r₅	r₄	r₃	r₂	r₁	r₀	g₇	g₆	g₅	g₄	g₃	g₂	g₁	g₀	b₇	b₆	b₅	b₄	b₃	b₂	b₁	b₀
`V4L2_PIX_FMT_ARGB32`	'BA24'	a₇	a₆	a₅	a₄	a₃	a₂	a₁	a₀	r₇	r₆	r₅	r₄	r₃	r₂	r₁	r₀	g₇	g₆	g₅	g₄	g₃	g₂	g₁	g₀	b₇	b₆	b₅	b₄	b₃	b₂	b₁	b₀
`V4L2_PIX_FMT_XRGB32`	'BX24'									r₇	r₆	r₅	r₄	r₃	r₂	r₁	r₀	g₇	g₆	g₅	g₄	g₃	g₂	g₁	g₀	b₇	b₆	b₅	b₄	b₃	b₂	b₁	b₀

Note

Bit 7 is the most significant bit.

The usage and value of the alpha bits (a) in the ARGB and ABGR formats (collectively referred to as alpha formats) depend on the device type and hardware operation. Capture devices (including capture queues of mem-to-mem devices) fill the alpha component in memory. When the device outputs an alpha channel the alpha component will have a meaningful value. Otherwise, when the device doesn't output an alpha channel but can set the alpha bit to a user-configurable value, the V4L2_CID_ALPHA_COMPONENT control is used to specify that alpha value, and the alpha component of all pixels will be set to the value specified by that control. Otherwise a corresponding format without an alpha component (XRGB or XBGR) must be used instead of an alpha format.

Output devices (including output queues of mem-to-mem devices and video output overlay devices) read the alpha component from memory. When the device processes the alpha channel the alpha component must be filled with meaningful values by applications. Otherwise a corresponding format without an alpha component (XRGB or XBGR) must be used instead of an alpha format.

The XRGB and XBGR formats contain undefined bits (-). Applications, devices and drivers must ignore those bits, for both Video Capture Interface and Video Output Interface devices.

Byte Order. Each cell is one byte.

RGB byte order¶
start + 0:	B₀₀	G₀₀	R₀₀	B₀₁	G₀₁	R₀₁	B₀₂	G₀₂	R₀₂	B₀₃	G₀₃	R₀₃
start + 12:	B₁₀	G₁₀	R₁₀	B₁₁	G₁₁	R₁₁	B₁₂	G₁₂	R₁₂	B₁₃	G₁₃	R₁₃
start + 24:	B₂₀	G₂₀	R₂₀	B₂₁	G₂₁	R₂₁	B₂₂	G₂₂	R₂₂	B₂₃	G₂₃	R₂₃
start + 36:	B₃₀	G₃₀	R₃₀	B₃₁	G₃₁	R₃₁	B₃₂	G₃₂	R₃₂	B₃₃	G₃₃	R₃₃

Formats defined in Deprecated Packed RGB Image Formats are deprecated and must not be used by new drivers. They are documented here for reference. The meaning of their alpha bits (a) are ill-defined and interpreted as in either the corresponding ARGB or XRGB format, depending on the driver.

Deprecated Packed RGB Image Formats¶
Identifier	Code	Byte 0 in memory								Byte 1								Byte 2								Byte 3
		7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
`V4L2_PIX_FMT_RGB444`	'R444'	g₃	g₂	g₁	g₀	b₃	b₂	b₁	b₀	a₃	a₂	a₁	a₀	r₃	r₂	r₁	r₀
`V4L2_PIX_FMT_RGB555`	'RGBO'	g₂	g₁	g₀	b₄	b₃	b₂	b₁	b₀	a	r₄	r₃	r₂	r₁	r₀	g₄	g₃
`V4L2_PIX_FMT_RGB555X`	'RGBQ'	a	r₄	r₃	r₂	r₁	r₀	g₄	g₃	g₂	g₁	g₀	b₄	b₃	b₂	b₁	b₀
`V4L2_PIX_FMT_BGR32`	'BGR4'	b₇	b₆	b₅	b₄	b₃	b₂	b₁	b₀	g₇	g₆	g₅	g₄	g₃	g₂	g₁	g₀	r₇	r₆	r₅	r₄	r₃	r₂	r₁	r₀	a₇	a₆	a₅	a₄	a₃	a₂	a₁	a₀
`V4L2_PIX_FMT_RGB32`	'RGB4'	a₇	a₆	a₅	a₄	a₃	a₂	a₁	a₀	r₇	r₆	r₅	r₄	r₃	r₂	r₁	r₀	g₇	g₆	g₅	g₄	g₃	g₂	g₁	g₀	b₇	b₆	b₅	b₄	b₃	b₂	b₁	b₀

A test utility to determine which RGB formats a driver actually supports is available from the LinuxTV v4l-dvb repository. See https://linuxtv.org/repo/ for access instructions.