The Pixel Rosetta Stone: Packings and Colorspaces

Assembled by Chris Pirazzi. Information provided by folks throughout the company, including Brian Beach, David Blythe, Nelson Bolyard, Terry Crane, Patricia Creek, Carolyn Curtis, Hilton Goldstein, Bent Hagemark, Angela Lai, Michael Minakami, Paul Ning, Michael Portuesi, Mark Segal, Paul Spencer, Mike Travis, Ashok Yerneni, and several mailing lists.

This document has two goals:

Describe all of the current VL packings.
Describe the current OpenGL, IRIS GL, DM, and CL packings which overlap with the VL packings or are otherwise useful to video developers.

This document makes no attempt at generality. As new packings and colorspaces are born, or otherwise become useful to video developers, we'll change our descriptive mechanism to fit them. The sections are:

Introduction:
- Tower of Babel?
- Packing vs. Colorspace
Packings:
Sampling Pattern Definitions:
How to Tell Which Colorspace You Have

Introduction

Tower of Babel?

Your first question is probably "Which of these zillions of packings are useful?" Each of these packings has some reason to exist, but the three most commonly used packings are:

Good ol' 4-byte-per-pixel OpenGL RGBA.
- Implemented on all VL and OpenGL devices.
2-byte-per-pixel 4:2:2 sampled YCrCb.
- Implemented on all VL devices (watch out for colorspace issues).
The older 4-byte-per-pixel IRIS GL ABGR.
- Implemented on all VL and IRIS GL devices up to IRIX 5.3.

Packing vs. Colorspace

In our model, all images have four components, numbered 1 through 4.

A packing

determines which of the four components are sampled.
determines the sampling pattern (4:4:4, 4:2:2, etc.), which specifies where and how often each component of the image is sampled. See Sampling Pattern Definitions for more information.
allocates a certain number of bits to represent the component samples, and positions those samples along with possible padding in memory.
determines the encoding of each component sample:
- 1-10 bit component samples are unsigned numbers.
  Numerical range is [0 to 2^nbits-1] where nbits is 1-10.
- 12-13 bit component samples are two's complement signed numbers.
  Numerical range is [-2^(nbits-1), 2^(nbits-1)-1] where nbits is 12-13.
The 1-10 bit unsigned representations provide different levels of precision for the same range of component levels. So value 0 and value 2^nbits-1 represent the same component level regardless of nbits.
The 12-13 bit signed representations provide precision equivalent to the 10 bit unsigned representation, over a wider range of component levels than the 10 bit unsigned representation. A 10 bit unsigned component with value V represents the same component level as a 12-13 bit signed component with value V. The 12-13 bit signed representation therefore can represent component levels outside the normal 10 bit range.

A colorspace

determines the color of each of the components. two choices:
- RGB ("rgba" in diagrams above): The familiar red, green, and blue, plus alpha.
  
  Our Component Number
  (meaningful only in this document) 1 2 3 4
  Interpretation r g b a
- YCrCb/YUV ("vyua" in diagrams above): Separate luma and chroma, plus alpha.
  
  Our Component Number
  (meaningful only in this document) 1 2 3 4
  Interpretation v / Cr y u / Cb a
  The most common representation of color from the video world, YCrCb or YUV represents each color by a luma component called Y and two components of chroma, called Cr (or V), and Cb (or U). The luma component is loosely related to "brightness" or "luminance," and the chroma components make up a quantity loosely related to "hue." These components are defined rigorously in ITU-R BT.601-4 (also known as Rec. 601 and formerly CCIR 601).
  When referring to the chroma components, it's probably better to use Cr and Cb than V and U, because the analog NTSC video specification ANSI/SMPTE 170M uses V and U with a slightly different meaning. This document uses the letters "v" and "u" in the diagrams above for typographical convenience.
What color is R, G, B, Y, Cr, or Cb? An excellent book for more information about colorspaces is "A Technical Introduction to Digital Video" by Charles A. Poynton (New York: Wiley, 1996).
The alpha channel is not a real color. For that channel, the canonical minimum value means "completely transparent," and the canonical maximum value means "completely opaque."
specifies a canonical minimum and maximum value for each component.
Normally, a component stays within the minimum and maximum values, inclusive. For example, for a luma signal such as Y, you can think of these limits as the "black" level and the "peak white" level. Given an unsigned component with n bits, there are two possibilities for [minimum value, maximum value]:
- full-range:
  - [0, (2^n)-1]
  - This range provides the maximum resolution for each component.
- headroom-range:
  - Cr and Cb: [(2^n)/16, 15*(2^n)/16]
  - Y, A, R, G, B: [(2^n)/16, 235*(2^n)/256]
  - This range is defined for 8 and 10 bits in ITU-R BT.601-4 (Rec. 601).
  - example: 8-bit components: Cr and Cb: [16, 240]. Y, A, R, G, B: [16, 235].
  - example: 10-bit components: Cr and Cb: [64, 960]. Y, A, R, G, B: [64, 940].
  - This range provides numerical headroom, which is often useful when processing video images.
  - Values in the range [0,(2^n)/256-1] and [255*(2^n)/256,(2^n)-1] are strictly forbidden. Input devices will strip out all such values. Output devices will substitute all such values with another nearby value.
As described above, 12-13 bit signed components have the same scale and offset as 10 bit unsigned components, but can represent additional values outside of the unsigned 10 bit range. Therefore, 12-13 bit signed components have the same canonical minimum and maximum value as 10 bit unsigned components.

Our Component Number (meaningful only in this document)	1	2	3	4
Interpretation	r	g	b	a

Our Component Number (meaningful only in this document)	1	2	3	4
Interpretation	v / Cr	y	u / Cb	a

In most SGI libraries, a single token encodes both colorspace and packing. Often, details of the colorspace are implicit. For the VL of divo and beyond, the two parameters are specified separately and explicitly, using VL_PACKING and VL_COLORSPACE. See How to Tell Which Colorspace You Have to understand which libraries use which colorspace when.

If you were wondering, 12-13 bit signed components are useful for storing rgba components which have been converted from the vyua color set. For example, this happens when you transfer in-memory RGB pixels to or from an external Rec. 601 digital video signal. Because of the way the color sets are defined, there exist vyua values which map outside of the normal rgba color cube. The rgba values must either be clamped, in which case information is lost, or the rgba component representation must be allowed to exceed the normal values. This is fully described in the most excellent Appendix "Color-Space Conversions" of the DIVO (Digital Video Option) XIO Board Owner's Guide.

Packings

How to Read the Packing Diagrams

In the diagrams below,

As you move from left to right along the diagram,
- Each byte goes from the most significant bit to the least significant bit.
- The bytes increase in memory address by 1.
- Component samples go from most significant bit to least significant bit.
We show the smallest repeating spatial pattern of component samples that is a multiple of 8 bits wide.
No additional padding or alignment is to be inferred. For example, this 24-bit-per-pixel diagram indicates 3-byte quantities packed together in memory. The values are not padded out to 32 bit boundaries.
When an "x" ("don't care") appears in a bit of the diagram, it means:
- Readers may get any garbage in the bit.
- Writers may leave the bit as garbage.
When a "0" appears in a bit of the diagram, it means:
- Readers may assume the bit is zero.
- Writers must zero out the bit.
- Exception: writers in a memory-to-video VL path may leave the bit as garbage.
When an "s" appears in a bit of the diagram, the bit contains a sign extension (replication) of the next least significant bit.
When a "p" appears in a bit of the diagram, it means:
- This packing contains 10-, 12-, or 13-bit components left-justified in larger words. See VL_PACKING_R242_10_in_16_L for an example.
- The "p" bits constitue the padding of the least significant bits of the word.
- Readers may assume the bit is zero.
- Exception: Readers in a divo video-to-memory VL path may assume that the bits are replicated from the component found in the same word. Assume the component's bits are numbered with 0 as the least significant bit. Assume there are n contiguous "p" bits to the right of the component. Those "p" bits contain a copy of bits [9,9-n+1] of the component. This device dependency is unfortunate.
- Writers must zero out the bit.
- Exception: writers in a memory-to-video VL path may leave the bit as garbage.
The packing really defines a bit layout for the abstract components 1, 2, 3, 4, but for convenience we have filled the component slots with the "rgba" or "vyua" color set where appropriate. See Packing vs. Colorspace for more information.
For packings which use 4:2:2 or 4:2:0 sampling, we also show the spatial location of each component sample. We indicate "left" and "right" for 4:2:2, and "top left," "top right," "bottom left," "bottom right," and "center" for 4:2:0. Our diagrams assume row-major, left-to-right ordering of pixels in memory.
Following each packing diagram is a list of comments and library tokens which refer to that packing. We list the color set ("rgba" or "vyua") and the library ("VL," "OpenGL," "IRIS GL," "DM," or "CL") for each library token. "DM" refers to the tokens in /usr/lib/dmedia/dm_image.h, which are used by several libraries (libdmedia (dmParams, dmIC, dmColor), libmoviefile, libmovieplay, and others). See Packing vs. Colorspace for more information.
We indicate which packings are supported by which VL devices. "Supported by xxx hardware" means the xxx device natively transfers data of that packing in real-time. "Supported by xxx software" means the xxx device's VL software implementation will automatically convert pixels from a native device format into that packing, which may or may not happen in real time.

Pixel Packings, Sorted by Width

8 Bit Pixel Packings

Pixel 1
Byte 1
y	y	y	y	y	y	y	y

(vyua) Monochrome/luma-only signal
(vyua) Supported by vino hardware
(vyua) Supported by ev1 software
(vyua) Supported by ev3 software for single-link i/o
(vyua) Supported by divo hardware
(vyua) (DM) DM_IMAGE_PACKING_LUMINANCE
(vyua) (CL) CL_FORMAT_GRAYSCALE
(vyua) (VL) VL_PACKING_4_8 + VL_COLORSPACE_{CCIR,YUV}
(vyua) (VL) VL_PACKING_Y_8_P
(vyua) (OpenGL) GL_LUMINANCE GL_UNSIGNED_BYTE
(vyua) (IRIS GL) PM_LUMINANCE PM_UNSIGNED_BYTE on RealityEngine

Pixel 1
Byte 1
b b g g g r r r

Pixel 1
Byte 1
b	b	g	g	g	r	r	r

(rgba) Supported by vino hardware
(rgba) Supported by Newport (indy) graphics and XL graphics hardware
(rgba) Supported by ev1 software
(rgba) Supported by ev3 software for single-link i/o
(rgba) Supported by divo hardware
(rgba) (DM) DM_IMAGE_PACKING_BGR233
(rgba) (CL) CL_FORMAT_BGR233
(rgba) (VL) VL_PACKING_R444_332 + VL_COLORSPACE_{RGB,RP175}
(rgba) (VL) VL_PACKING_RGB_332_P
(rgba) (IRIS GL) PM_SIZE=9 on Newport, XL

Pixel 1
Byte 1
r r r b b g g g

Pixel 1
Byte 1
r	r	r	b	b	g	g	g

(rgba) Obsolete: used with Indigo Entry graphics and Starter Video.
(rgba) Pixmode man page incorrectly describes this packing.
(rgba) (DM) DM_IMAGE_PACKING_RBG323
(rgba) (CL) CL_FORMAT_RBG323
(rgba) (VL) VL_PACKING_X444_332 + VL_COLORSPACE_{RGB,RP175}
(rgba) (VL) VL_PACKING_RBG_323
(rgba) (IRIS GL) PM_SIZE=8 on Indigo Entry

Pixel 1
Byte 1
r r r g g g b b

Pixel 1
Byte 1
r	r	r	g	g	g	b	b

(rgba) Supported by O2 (CRM) graphics
(rgba) Supported by divo hardware
(rgba) (DM) DM_IMAGE_PACKING_RGB332
(rgba) (VL) VL_PACKING_444_332 + VL_COLORSPACE_{RGB,RP175}
(rgba) (OpenGL) GL_RGB GL_UNSIGNED_BYTE_3_3_2_EXT

12 Bit Pixel Packings

Pixels 1-4
Byte 1								Byte 2								Byte 3								Byte 4								Byte 5								Byte 6
u	u	u	u	u	u	u	u	y	y	y	y	y	y	y	y	v	v	v	v	v	v	v	v	y	y	y	y	y	y	y	y	y	y	y	y	y	y	y	y	y	y	y	y	y	y	y	y
center								top left								center								top right								bottom left								bottom right

(vyua) 4:2:0 sampling as in MPEG and H.261
(vyua) (DM) DM_IMAGE_PACKING_CbYCrYYY - See the document CL_FORMAT_YCbCr422DC and DM_IMAGE_PACKING_CbYCrYYY for an example.
(vyua) the CL also has a 4:2:0 packing: check out CL_FORMAT_YCbCr422DC.

16 Bit Pixel Packings

Pixel 1
Byte 1								Byte 2
y	y	y	y	y	y	y	y	a	a	a	a	a	a	a	a

(vyua) Luminance/Alpha packing supported by colorspace library and GL
(vyua) (DM) DM_IMAGE_PACKING_LUMINANCE_ALPHA
(vyua) (OpenGL) GL_LUMINANCE_ALPHA GL_UNSIGNED_BYTE
(vyua) (IRIS GL) PM_LUMINANCEA PM_UNSIGNED_BYTE on RealityEngine

Pixels 1-2
Byte 1 Byte 2 Byte 3 Byte 4
v v v v v v v v y y y y y y y y u u u u u u u u y y y y y y y y
left right

Pixels 1-2
Byte 1	Byte 2	Byte 3	Byte 4
v	v	v	v	v	v	v	v	y	y	y	y	y	y	y	y	u	u	u	u	u	u	u	u	y	y	y	y	y	y	y	y
left	right

(vyua) Rarely used. 4:2:2 sampling.
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_242_8 + VL_COLORSPACE_{CCIR,YUV}

Pixels 1-2
Byte 1 Byte 2 Byte 3 Byte 4
u u u u u u u u y y y y y y y y v v v v v v v v y y y y y y y y
left right

Pixels 1-2
Byte 1	Byte 2	Byte 3	Byte 4
u	u	u	u	u	u	u	u	y	y	y	y	y	y	y	y	v	v	v	v	v	v	v	v	y	y	y	y	y	y	y	y
left	right

(vyua) Most commonly used 4:2:2 packing.
(vyua) Supported by vino hardware
(vyua) Supported by ev1 software
(vyua) Supported by ev3 hardware for single link i/o
(vyua) Supported by sirius hardware
(vyua) Supported by mvp hardware
(vyua) Supported by divo hardware
(vyua) Supported by O2 (CRM) graphics hardware. For OpenGL examples, check out Displaying In-Memory Video using OpenGL and Rendering graphics onto video.
(vyua) (DM) DM_IMAGE_PACKING_CbYCrY
(vyua) (CL) CL_FORMAT_YCbCr422
(vyua) (VL) VL_PACKING_R242_8 + VL_COLORSPACE_{CCIR,YUV}
(vyua) (VL) VL_PACKING_YVYU_422_8
(vyua) (CL) CL_FORMAT_YCbCr422DC: actually a 4:2:0 packing. See the document CL_FORMAT_YCbCr422DC and DM_IMAGE_PACKING_CbYCrYYY for info.
(vyua) (OpenGL) GL_YCRCB_422_SGIX GL_UNSIGNED_BYTE

Pixel 1
Byte 1 Byte 2
a r r r r r g g g g g b b b b b

Pixel 1
Byte 1	Byte 2
a	r	r	r	r	r	g	g	g	g	g	b	b	b	b	b

(rgba) Supported by O2 (CRM) graphics hardware for pbuffers and textures, but not glDrawPixels(). Even though the token DM_IMAGE_PACKING_XRGB1555 is used, the upper bit is really alpha.
(rgba) Supported by mvp hardware
(rgba) Supported by divo hardware
(rgba) Quicktime file 16-bit uncompressed format with alpha.
(rgba) (DM) DM_IMAGE_PACKING_XRGB1555
(rgba) (VL) VL_PACKING_X4444_5551 + VL_COLORSPACE_{RGB,RP175}
(rgba) (VL) VL_PACKING_ARGB_1555

Pixel 1
Byte 1 Byte 2
r r r r r g g g g g b b b b b a

Pixel 1
Byte 1	Byte 2
r	r	r	r	r	g	g	g	g	g	b	b	b	b	b	a

(rgba) Apparently Useless. Not supported by any graphics or video hardware.
(rgba) (DM) DM_IMAGE_PACKING_RGBA5551
(rgba) (OpenGL) GL_RGBA GL_UNSIGNED_SHORT_5_5_5_1_EXT

Pixel 1
Byte 1 Byte 2
r r r r r g g g g g g b b b b b

Pixel 1
Byte 1	Byte 2
r	r	r	r	r	g	g	g	g	g	g	b	b	b	b	b

(rgba) Supposedly common in the PC world.
(rgba) Supported by divo hardware
(rgba) (VL) VL_PACKING_444_5_6_5 + VL_COLORSPACE_{RGB,RP175}

20 Bit Pixel Packings

Pixels 1-2
Byte 1								Byte 2								Byte 3								Byte 4								Byte 5
u	u	u	u	u	u	u	u	u	u	y	y	y	y	y	y	y	y	y	y	v	v	v	v	v	v	v	v	v	v	y	y	y	y	y	y	y	y	y	y
left																														right

(vyua) 4:2:2 sampling
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_R242_10 + VL_COLORSPACE_{CCIR,YUV}

Pixels 1-2
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5
v v v v v v v v v v y y y y y y y y y y u u u u u u u u u u y y y y y y y y y y
left right

Pixels 1-2
Byte 1	Byte 2	Byte 3	Byte 4	Byte 5
v	v	v	v	v	v	v	v	v	v	y	y	y	y	y	y	y	y	y	y	u	u	u	u	u	u	u	u	u	u	y	y	y	y	y	y	y	y	y	y
left	right

(vyua) 4:2:2 sampling
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_242_10 + VL_COLORSPACE_{CCIR,YUV}

24 Bit Pixel Packings

Pixel 1
Byte 1								Byte 2								Byte 3
r	r	r	r	r	r	r	r	g	g	g	g	g	g	g	g	b	b	b	b	b	b	b	b
v	v	v	v	v	v	v	v	y	y	y	y	y	y	y	y	u	u	u	u	u	u	u	u

(rgba) Supported by divo hardware
(rgba) Supported by Octane ev3 hardware for dual-link RGB i/o
(rgba) (DM) DM_IMAGE_PACKING_RGB
(rgba) (VL) VL_PACKING_444_8 + VL_COLORSPACE_{RGB,RP175}
(rgba) (VL) VL_PACKING_BGR_8_P
(rgba) (OpenGL) GL_RGB GL_UNSIGNED_BYTE
(rgba) (IRIS GL) PM_RGB PM_UNSIGNED_BYTE on RealityEngine
(vyua) Supported by ev3 hardware for dual-link YCrCb i/o
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_444_8 + VL_COLORSPACE_{CCIR,YUV}
(vyua) (VL) VL_PACKING_UYV_8_P

Pixel 1
Byte 1 Byte 2 Byte 3
b b b b b b b b g g g g g g g g r r r r r r r r
u u u u u u u u y y y y y y y y v v v v v v v v

Pixel 1
Byte 1	Byte 2	Byte 3
b	b	b	b	b	b	b	b	g	g	g	g	g	g	g	g	r	r	r	r	r	r	r	r
u	u	u	u	u	u	u	u	y	y	y	y	y	y	y	y	v	v	v	v	v	v	v	v

(rgba) Supported by divo hardware
(rgba) (DM) DM_IMAGE_PACKING_BGR
(rgba) (CL) CL_FORMAT_BGR
(rgba) (VL) VL_PACKING_R444_8 + VL_COLORSPACE_{RGB,RP175}
(rgba) (VL) VL_PACKING_RGB_8_P
(rgba) (IRIS GL) PM_BGR PM_UNSIGNED_BYTE on RealityEngine
(vyua) Supported by divo hardware
(vyua) (DM) DM_IMAGE_PACKING_CbYCr
(vyua) (CL) CL_FORMAT_YCbCr
(vyua) (VL) VL_PACKING_R444_8 + VL_COLORSPACE_{CCIR,YUV}

Pixel 1
Byte 1 Byte 2 Byte 3
r r r r r r g g g g g g b b b b b b a a a a a a
v v v v v v y y y y y y u u u u u u a a a a a a

Pixel 1
Byte 1	Byte 2	Byte 3
r	r	r	r	r	r	g	g	g	g	g	g	b	b	b	b	b	b	a	a	a	a	a	a
v	v	v	v	v	v	y	y	y	y	y	y	u	u	u	u	u	u	a	a	a	a	a	a

(rgba) 6 bits per pixel
(rgba) Supported by divo hardware
(rgba) (VL) VL_PACKING_4444_6 + VL_COLORSPACE_{RGB,RP175}
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_4444_6 + VL_COLORSPACE_{CCIR,YUV}

OpenGL-Like 32-bit Packings:

Pixel 1
Byte 1								Byte 2								Byte 3								Byte 4
r	r	r	r	r	r	r	r	g	g	g	g	g	g	g	g	b	b	b	b	b	b	b	b	a	a	a	a	a	a	a	a
v	v	v	v	v	v	v	v	y	y	y	y	y	y	y	y	u	u	u	u	u	u	u	u	a	a	a	a	a	a	a	a

(rgba) Most commonly used OpenGL Packing
(rgba) Supported by ev1 software (A is 0)
(rgba) Supported by ev3 software for single-link i/o (A is 0)
(rgba) Supported by ev3 hardware for dual-link RGBA i/o
(rgba) Supported by sirius hardware
(rgba) Supported by mvp hardware (A is a settable constant)
(rgba) Supported by divo hardware
(rgba) (DM) DM_IMAGE_PACKING_RGBA
(rgba) (VL) VL_PACKING_4444_8 + VL_COLORSPACE_{RGB,RP175}
(rgba) (VL) VL_PACKING_ABGR_8
(rgba) (OpenGL) GL_RGBA GL_UNSIGNED_BYTE (most commonly used OpenGL packing)
(rgba) (IRIS GL) PM_RGBA PM_UNSIGNED_BYTE on RealityEngine
(vyua) Supported by ev3 hardware for dual-link YCrCbA i/o
(vyua) Supported by sirius hardware
(vyua) Supported by mvp hardware (A is a settable constant)
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_4444_8 + VL_COLORSPACE_{CCIR,YUV}
(vyua) (VL) VL_PACKING_AUYV_4444_8 or VL_PACKING_AUYV_8

Pixel 1
Byte 1 Byte 2 Byte 3 Byte 4
r r r r r r r r g g g g g g g g b b b b b b b b x x x x x x x x

Pixel 1
Byte 1	Byte 2	Byte 3	Byte 4
r	r	r	r	r	r	r	r	g	g	g	g	g	g	g	g	b	b	b	b	b	b	b	b	x	x	x	x	x	x	x	x

(rgba) Use DM_IMAGE_PACKING_RGBA instead of DM_IMAGE_PACKING_RGBX unless you specifically want to inform a piece of software (such as dmColor) not to spend processing time on the alpha channel.
(rgba) (DM) DM_IMAGE_PACKING_RGBX

IRIS GL-Like 32-bit Packings:

Pixel 1
Byte 1								Byte 2								Byte 3								Byte 4
a	a	a	a	a	a	a	a	b	b	b	b	b	b	b	b	g	g	g	g	g	g	g	g	r	r	r	r	r	r	r	r
a	a	a	a	a	a	a	a	u	u	u	u	u	u	u	u	y	y	y	y	y	y	y	y	v	v	v	v	v	v	v	v

(rgba) Default IRIS GL Packing
(rgba) Supported by vino hardware (A is a settable constant)
(rgba) Supported by ev1 software (A is 0)
(rgba) Supported by ev3 software for single-link i/o (A is 0)
(rgba) Supported by ev3 hardware for dual-link RGBA i/o
(rgba) Supported by sirius hardware
(rgba) Supported by mvp hardware (A is a settable constant)
(rgba) Supported by divo hardware
(rgba) (DM) DM_IMAGE_PACKING_ABGR
(rgba) (CL) CL_FORMAT_ABGR
(rgba) (VL) VL_PACKING_R4444_8 + VL_COLORSPACE_{RGB,RP175}
(rgba) (VL) VL_PACKING_RGBA_8
(rgba) (OpenGL) GL_ABGR_EXT GL_UNSIGNED_BYTE
(rgba) (IRIS GL) PM_ABGR PM_UNSIGNED_BYTE (the default IRIS GL packing)
(vyua) Supported by ev3 hardware for dual-link YCrCbA i/o. Non-full-size (cropped or zoomed) output may have green padding on some Octane ev3 models.
(vyua) Supported by sirius hardware
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_R4444_8 + VL_COLORSPACE_{CCIR,YUV}
(vyua) (VL) VL_PACKING_YUVA_4444_8

Pixel 1
Byte 1 Byte 2 Byte 3 Byte 4
x x x x x x x x b b b b b b b b g g g g g g g g r r r r r r r r
x x x x x x x x u u u u u u u u y y y y y y y y v v v v v v v v

Pixel 1
Byte 1	Byte 2	Byte 3	Byte 4
x	x	x	x	x	x	x	x	b	b	b	b	b	b	b	b	g	g	g	g	g	g	g	g	r	r	r	r	r	r	r	r
x	x	x	x	x	x	x	x	u	u	u	u	u	u	u	u	y	y	y	y	y	y	y	y	v	v	v	v	v	v	v	v

(rgba) Use DM_IMAGE_PACKING_ABGR instead of DM_IMAGE_PACKING_XBGR unless you specifically want to inform a piece of software (such as dmColor) not to spend processing time on the alpha channel.
(rgba) Often interchangeable with Default IRIS GL Packing
(rgba) Supported by ev1 software
(rgba) Supported by ev3 software for single-link i/o
(rgba) Supported by ev3 hardware for dual-link RGBA i/o
(rgba) Supported by sirius hardware
(rgba) Supported by divo hardware
(rgba) (DM) DM_IMAGE_PACKING_XBGR
(rgba) (CL) CL_FORMAT_XBGR
(rgba) (VL) VL_PACKING_R0444_8 + VL_COLORSPACE_{RGB,RP175}
(rgba) (VL) VL_PACKING_RGB_8
(vyua) Supported by ev3 hardware for dual-link YCrCbA i/o
(vyua) Supported by sirius hardware
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_R0444_8 + VL_COLORSPACE_{CCIR,YUV}
(vyua) (VL) VL_PACKING_YUV_444_8

Unusual 32-bit Packings:

Pixel 1
Byte 1								Byte 2								Byte 3								Byte 4
a	a	a	a	a	a	a	a	r	r	r	r	r	r	r	r	g	g	g	g	g	g	g	g	b	b	b	b	b	b	b	b

(rgba) Quicktime 32-bit uncompressed format with alpha.
(rgba) (DM) DM_IMAGE_PACKING_ARGB

Pixel 1
Byte 1 Byte 2 Byte 3 Byte 4
x x x x x x x x r r r r r r r r g g g g g g g g b b b b b b b b
x x x x x x x x v v v v v v v v y y y y y y y y u u u u u u u u

Pixel 1
Byte 1	Byte 2	Byte 3	Byte 4
x	x	x	x	x	x	x	x	r	r	r	r	r	r	r	r	g	g	g	g	g	g	g	g	b	b	b	b	b	b	b	b
x	x	x	x	x	x	x	x	v	v	v	v	v	v	v	v	y	y	y	y	y	y	y	y	u	u	u	u	u	u	u	u

(rgba) Quicktime file 32-bit uncompressed format without alpha
(rgba) Supported by divo hardware
(rgba) (DM) DM_IMAGE_PACKING_XRGB
(rgba) (VL) VL_PACKING_0444_8 + VL_COLORSPACE_{RGB,RP175}
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_0444_8 + VL_COLORSPACE_{CCIR,YUV}

Pixel 1
Byte 1 Byte 2 Byte 3 Byte 4
u u u u u u u u y y y y y y y y v v v v v v v v a a a a a a a a

Pixel 1
Byte 1	Byte 2	Byte 3	Byte 4
u	u	u	u	u	u	u	u	y	y	y	y	y	y	y	y	v	v	v	v	v	v	v	v	a	a	a	a	a	a	a	a

(vyua) Rarely Used. Component order not compatible with any hardware.
4:4:4:4 sampled YCrCb with alpha.
(vyua) (DM) DM_IMAGE_PACKING_CbYCrA

4:4:4:4 10_10_10_2 32-bit Packings:

Pixel 1
Byte 1								Byte 2								Byte 3								Byte 4
r	r	r	r	r	r	r	r	r	r	g	g	g	g	g	g	g	g	g	g	b	b	b	b	b	b	b	b	b	b	a	a
v	v	v	v	v	v	v	v	v	v	y	y	y	y	y	y	y	y	y	y	u	u	u	u	u	u	u	u	u	u	a	a

(rgba) Supported by sirius hardware
(rgba) Supported by divo hardware
(rgba) Supported by Octane ev3 hardware for dual-link RGBA i/o
(rgba) (VL) VL_PACKING_4444_10_10_10_2 + VL_COLORSPACE_{RGB,RP175}
(rgba) (VL) VL_PACKING_A_2_BGR_10
(rgba) (OpenGL) GL_RGBA GL_UNSIGNED_INT_10_10_10_2_EXT
(vyua) Supported by sirius hardware
(vyua) Supported by divo hardware
(vyua) Supported by Octane ev3 hardware for dual-link YCrCbA i/o
(vyua) (VL) VL_PACKING_4444_10_10_10_2 + VL_COLORSPACE_{CCIR,YUV}
(vyua) (VL) VL_PACKING_A_2_UYV_10

Pixel 1
Byte 1 Byte 2 Byte 3 Byte 4
a a b b b b b b b b b b g g g g g g g g g g r r r r r r r r r r
a a u u u u u u u u u u y y y y y y y y y y v v v v v v v v v v

Pixel 1
Byte 1	Byte 2	Byte 3	Byte 4
a	a	b	b	b	b	b	b	b	b	b	b	g	g	g	g	g	g	g	g	g	g	r	r	r	r	r	r	r	r	r	r
a	a	u	u	u	u	u	u	u	u	u	u	y	y	y	y	y	y	y	y	y	y	v	v	v	v	v	v	v	v	v	v

(rgba) Not currently supported by any VL device
(rgba) (VL) VL_PACKING_R4444_10_10_10_2 + VL_COLORSPACE_{RGB,RP175}
(rgba) (OpenGL) GL_ABGR_EXT GL_UNSIGNED_INT_10_10_10_2_EXT
(vyua) Not currently supported by any VL device
(vyua) (VL) VL_PACKING_R4444_10_10_10_2 + VL_COLORSPACE_{CCIR,YUV}

4:2:2:4 10_10_10_2 32-bit Packings:

Pixels 1-2
Byte 1								Byte 2								Byte 3								Byte 4								Byte 5								Byte 6								Byte 7								Byte 8
v	v	v	v	v	v	v	v	v	v	y	y	y	y	y	y	y	y	y	y	a	a	a	a	a	a	a	a	a	a	0	0	u	u	u	u	u	u	u	u	u	u	y	y	y	y	y	y	y	y	y	y	a	a	a	a	a	a	a	a	a	a	0	0
left																														0	0	left										right																				0	0

(vyua) 4:2:2:4 sampling (2 bits of A)
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_2424_10_10_10_2Z + VL_COLORSPACE_{CCIR,YUV}

Pixels 1-2
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8
u u u u u u u u u u y y y y y y y y y y a a a a a a a a a a 0 0 v v v v v v v v v v y y y y y y y y y y a a a a a a a a a a 0 0
left 0 0 left right 0 0

Pixels 1-2
Byte 1	Byte 2	Byte 3	Byte 4	Byte 5	Byte 6	Byte 7	Byte 8
u	u	u	u	u	u	u	u	u	u	y	y	y	y	y	y	y	y	y	y	a	a	a	a	a	a	a	a	a	a	0	0	v	v	v	v	v	v	v	v	v	v	y	y	y	y	y	y	y	y	y	y	a	a	a	a	a	a	a	a	a	a	0	0
left	0	0	left	right	0	0

(vyua) 4:2:2:4 sampling (2 bits of A)
(vyua) Supported by ev3 hardware for dual-link YCrCbA i/o. Note YCrCb data is 4:2:2---only alpha is extracted from second link.
(vyua) Supported by sirius hardware
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_R2424_10_10_10_2Z + VL_COLORSPACE_{CCIR,YUV}
(vyua) (VL) VL_PACKING_AYU_AYV_10

4:2:2 10_in_16 32-bit Packings:

Pixels 1-2
Byte 1								Byte 2								Byte 3								Byte 4								Byte 5								Byte 6								Byte 7								Byte 8
v	v	v	v	v	v	v	v	v	v	p	p	p	p	p	p	y	y	y	y	y	y	y	y	y	y	p	p	p	p	p	p	u	u	u	u	u	u	u	u	u	u	p	p	p	p	p	p	y	y	y	y	y	y	y	y	y	y	p	p	p	p	p	p
left										p	p	p	p	p	p	left										p	p	p	p	p	p	left										p	p	p	p	p	p	right										p	p	p	p	p	p

(vyua) 4:2:2 sampling
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_242_10_in_16_L + VL_COLORSPACE_{CCIR,YUV}

Pixels 1-2
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8
0 0 0 0 0 0 v v v v v v v v v v 0 0 0 0 0 0 y y y y y y y y y y 0 0 0 0 0 0 u u u u u u u u u u 0 0 0 0 0 0 y y y y y y y y y y
0 0 0 0 0 0 left 0 0 0 0 0 0 left 0 0 0 0 0 0 left 0 0 0 0 0 0 right

Pixels 1-2
Byte 1	Byte 2	Byte 3	Byte 4	Byte 5	Byte 6	Byte 7	Byte 8
0	0	0	0	0	0	v	v	v	v	v	v	v	v	v	v	0	0	0	0	0	0	y	y	y	y	y	y	y	y	y	y	0	0	0	0	0	0	u	u	u	u	u	u	u	u	u	u	0	0	0	0	0	0	y	y	y	y	y	y	y	y	y	y
0	0	0	0	0	0	left	0	0	0	0	0	0	left	0	0	0	0	0	0	left	0	0	0	0	0	0	right

(vyua) 4:2:2 sampling
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_242_10_in_16_R + VL_COLORSPACE_{CCIR,YUV}

Pixels 1-2
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8
u u u u u u u u u u p p p p p p y y y y y y y y y y p p p p p p v v v v v v v v v v p p p p p p y y y y y y y y y y p p p p p p
left p p p p p p left p p p p p p left p p p p p p right p p p p p p

Pixels 1-2
Byte 1	Byte 2	Byte 3	Byte 4	Byte 5	Byte 6	Byte 7	Byte 8
u	u	u	u	u	u	u	u	u	u	p	p	p	p	p	p	y	y	y	y	y	y	y	y	y	y	p	p	p	p	p	p	v	v	v	v	v	v	v	v	v	v	p	p	p	p	p	p	y	y	y	y	y	y	y	y	y	y	p	p	p	p	p	p
left	p	p	p	p	p	p	left	p	p	p	p	p	p	left	p	p	p	p	p	p	right	p	p	p	p	p	p

(vyua) 4:2:2 sampling
(vyua) Supported by ev3 hardware for single-link i/o
(vyua) Supported by mvp hardware
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_R242_10_in_16_L + VL_COLORSPACE_{CCIR,YUV}
(vyua) (VL) VL_PACKING_YVYU_422_10

Pixels 1-2
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8
0 0 0 0 0 0 u u u u u u u u u u 0 0 0 0 0 0 y y y y y y y y y y 0 0 0 0 0 0 v v v v v v v v v v 0 0 0 0 0 0 y y y y y y y y y y
0 0 0 0 0 0 left 0 0 0 0 0 0 left 0 0 0 0 0 0 left 0 0 0 0 0 0 right

Pixels 1-2
Byte 1	Byte 2	Byte 3	Byte 4	Byte 5	Byte 6	Byte 7	Byte 8
0	0	0	0	0	0	u	u	u	u	u	u	u	u	u	u	0	0	0	0	0	0	y	y	y	y	y	y	y	y	y	y	0	0	0	0	0	0	v	v	v	v	v	v	v	v	v	v	0	0	0	0	0	0	y	y	y	y	y	y	y	y	y	y
0	0	0	0	0	0	left	0	0	0	0	0	0	left	0	0	0	0	0	0	left	0	0	0	0	0	0	right

(vyua) 4:2:2 sampling
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_R242_10_in_16_R + VL_COLORSPACE_{CCIR,YUV}

36 Bit Pixel Packings

Pixel 1																																				Pixel 2
Byte 1								Byte 2								Byte 3								Byte 4								Byte 5								Byte 6								Byte 7								Byte 8								Byte 9
r	r	r	r	r	r	r	r	r	r	r	r	g	g	g	g	g	g	g	g	g	g	g	g	b	b	b	b	b	b	b	b	b	b	b	b	r	r	r	r	r	r	r	r	r	r	r	r	g	g	g	g	g	g	g	g	g	g	g	g	b	b	b	b	b	b	b	b	b	b	b	b
v	v	v	v	v	v	v	v	v	v	v	v	y	y	y	y	y	y	y	y	y	y	y	y	u	u	u	u	u	u	u	u	u	u	u	u	v	v	v	v	v	v	v	v	v	v	v	v	y	y	y	y	y	y	y	y	y	y	y	y	u	u	u	u	u	u	u	u	u	u	u	u

(rgba) Note: components are two's complement signed integers
(rgba) Supported by divo hardware
(rgba) (VL) VL_PACKING_444_12 + VL_COLORSPACE_{RGB,RP175}
(vyua) Note: components are two's complement signed integers
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_444_12 + VL_COLORSPACE_{CCIR,YUV}

48 Bit Pixel Packings

Pixel 1
Byte 1								Byte 2								Byte 3								Byte 4								Byte 5								Byte 6
r	r	r	r	r	r	r	r	r	r	p	p	p	p	p	p	g	g	g	g	g	g	g	g	g	g	p	p	p	p	p	p	b	b	b	b	b	b	b	b	b	b	p	p	p	p	p	p
v	v	v	v	v	v	v	v	v	v	p	p	p	p	p	p	y	y	y	y	y	y	y	y	y	y	p	p	p	p	p	p	u	u	u	u	u	u	u	u	u	u	p	p	p	p	p	p

(rgba) Supported by divo hardware
(rgba) (VL) VL_PACKING_444_10_in_16_L + VL_COLORSPACE_{RGB,RP175}
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_444_10_in_16_L + VL_COLORSPACE_{CCIR,YUV}

Pixel 1
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6
r r r r r r r r r r r r g g g g g g g g g g g g b b b b b b b b b b b b a a a a a a a a a a a a
v v v v v v v v v v v v y y y y y y y y y y y y u u u u u u u u u u u u a a a a a a a a a a a a

Pixel 1
Byte 1	Byte 2	Byte 3	Byte 4	Byte 5	Byte 6
r	r	r	r	r	r	r	r	r	r	r	r	g	g	g	g	g	g	g	g	g	g	g	g	b	b	b	b	b	b	b	b	b	b	b	b	a	a	a	a	a	a	a	a	a	a	a	a
v	v	v	v	v	v	v	v	v	v	v	v	y	y	y	y	y	y	y	y	y	y	y	y	u	u	u	u	u	u	u	u	u	u	u	u	a	a	a	a	a	a	a	a	a	a	a	a

(rgba) Note: components are two's complement signed integers
(rgba) Supported by divo hardware
(rgba) (VL) VL_PACKING_4444_12 + VL_COLORSPACE_{RGB,RP175}
(vyua) Note: components are two's complement signed integers
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_4444_12 + VL_COLORSPACE_{CCIR,YUV}

64 Bit Pixel Packings

Pixel 1
Byte 1								Byte 2								Byte 3								Byte 4								Byte 5								Byte 6								Byte 7								Byte 8
r	r	r	r	r	r	r	r	r	r	p	p	p	p	p	p	g	g	g	g	g	g	g	g	g	g	p	p	p	p	p	p	b	b	b	b	b	b	b	b	b	b	p	p	p	p	p	p	a	a	a	a	a	a	a	a	a	a	p	p	p	p	p	p
v	v	v	v	v	v	v	v	v	v	p	p	p	p	p	p	y	y	y	y	y	y	y	y	y	y	p	p	p	p	p	p	u	u	u	u	u	u	u	u	u	u	p	p	p	p	p	p	a	a	a	a	a	a	a	a	a	a	p	p	p	p	p	p

(rgba) Supported by ev3 hardware for dual-link RGBA i/o
(rgba) Supported by divo hardware
(rgba) (VL) VL_PACKING_4444_10_in_16_L + VL_COLORSPACE_{RGB,RP175}
(rgba) (VL) VL_PACKING_ABGR_10
(vyua) Supported by ev3 hardware for dual-link YCrCb i/o
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_4444_10_in_16_L + VL_COLORSPACE_{CCIR,YUV}
(vyua) (VL) VL_PACKING_AUYV_4444_10

Pixel 1
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8
0 0 0 0 0 0 r r r r r r r r r r 0 0 0 0 0 0 g g g g g g g g g g 0 0 0 0 0 0 b b b b b b b b b b 0 0 0 0 0 0 a a a a a a a a a a
0 0 0 0 0 0 v v v v v v v v v v 0 0 0 0 0 0 y y y y y y y y y y 0 0 0 0 0 0 u u u u u u u u u u 0 0 0 0 0 0 a a a a a a a a a a

Pixel 1
Byte 1	Byte 2	Byte 3	Byte 4	Byte 5	Byte 6	Byte 7	Byte 8
0	0	0	0	0	0	r	r	r	r	r	r	r	r	r	r	0	0	0	0	0	0	g	g	g	g	g	g	g	g	g	g	0	0	0	0	0	0	b	b	b	b	b	b	b	b	b	b	0	0	0	0	0	0	a	a	a	a	a	a	a	a	a	a
0	0	0	0	0	0	v	v	v	v	v	v	v	v	v	v	0	0	0	0	0	0	y	y	y	y	y	y	y	y	y	y	0	0	0	0	0	0	u	u	u	u	u	u	u	u	u	u	0	0	0	0	0	0	a	a	a	a	a	a	a	a	a	a

(rgba) Supported by divo hardware
(rgba) (VL) VL_PACKING_4444_10_in_16_R + VL_COLORSPACE_{RGB,RP175}
(vyua) Supported by divo hardware
(vyua) (VL) VL_PACKING_4444_10_in_16_R + VL_COLORSPACE_{CCIR,YUV}

Pixel 1
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8
a a a a a a a a a a p p p p p p b b b b b b b b b b p p p p p p g g g g g g g g g g p p p p p p r r r r r r r r r r p p p p p p
a a a a a a a a a a p p p p p p u u u u u u u u u u p p p p p p y y y y y y y y y y p p p p p p v v v v v v v v v v p p p p p p

Pixel 1
Byte 1	Byte 2	Byte 3	Byte 4	Byte 5	Byte 6	Byte 7	Byte 8
a	a	a	a	a	a	a	a	a	a	p	p	p	p	p	p	b	b	b	b	b	b	b	b	b	b	p	p	p	p	p	p	g	g	g	g	g	g	g	g	g	g	p	p	p	p	p	p	r	r	r	r	r	r	r	r	r	r	p	p	p	p	p	p
a	a	a	a	a	a	a	a	a	a	p	p	p	p	p	p	u	u	u	u	u	u	u	u	u	u	p	p	p	p	p	p	y	y	y	y	y	y	y	y	y	y	p	p	p	p	p	p	v	v	v	v	v	v	v	v	v	v	p	p	p	p	p	p

(rgba) Supported by ev3 hardware for dual-link RGBA i/o
(rgba) (VL) VL_PACKING_R4444_10_in_16_L + VL_COLORSPACE_{RGB,RP175}
(rgba) (VL) VL_PACKING_RGBA_10
(vyua) Supported by ev3 hardware for dual-link YCrCbA i/o. Non-full-size (cropped or zoomed) output may have green padding on some Octane ev3 models.
(vyua) (VL) VL_PACKING_R4444_10_in_16_L + VL_COLORSPACE_{CCIR,YUV}
(vyua) (VL) VL_PACKING_YUVA_4444_10

Pixel 1
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8
x x x x x x x x x x p p p p p p b b b b b b b b b b p p p p p p g g g g g g g g g g p p p p p p r r r r r r r r r r p p p p p p

Pixel 1
Byte 1	Byte 2	Byte 3	Byte 4	Byte 5	Byte 6	Byte 7	Byte 8
x	x	x	x	x	x	x	x	x	x	p	p	p	p	p	p	b	b	b	b	b	b	b	b	b	b	p	p	p	p	p	p	g	g	g	g	g	g	g	g	g	g	p	p	p	p	p	p	r	r	r	r	r	r	r	r	r	r	p	p	p	p	p	p

(rgba) Supported by ev3 hardware for dual-link RGBA i/o
(rgba) (VL) VL_PACKING_R4440_10_in_16_L + VL_COLORSPACE_{RGB,RP175}
(rgba) (VL) VL_PACKING_RGB_10

Pixel 1
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8
r r r r r r r r r r r r p p p p g g g g g g g g g g g g p p p p b b b b b b b b b b b b p p p p a a a a a a a a a a a a p p p p

Pixel 1
Byte 1	Byte 2	Byte 3	Byte 4	Byte 5	Byte 6	Byte 7	Byte 8
r	r	r	r	r	r	r	r	r	r	r	r	p	p	p	p	g	g	g	g	g	g	g	g	g	g	g	g	p	p	p	p	b	b	b	b	b	b	b	b	b	b	b	b	p	p	p	p	a	a	a	a	a	a	a	a	a	a	a	a	p	p	p	p

(rgba) Note: components are two's complement signed integers
(rgba) Supported by divo hardware
(rgba) (VL) VL_PACKING_4444_12_in_16_L + VL_COLORSPACE_{RGB,RP175}
(rgba) (IRIS GL) PM_SIZE=64 on RealityEngine

Pixel 1
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5