USB Video Class study

Rec. 601 luma versus Rec. 709 luma coefficients

For digital formats following CCIR 601 (i.e. most digital standard definition formats), luma is calculated with the formula Y' = 0.299 R' + 0.587 G' + 0.114 B'. Formats following ITU-R Recommendation BT. 709 use the formula Y' = 0.2126 R' + 0.7152 G' + 0.0722 B'. Modern HDTV systems use the 709 coefficients, while transitional 1035i HDTV formats may use the SMPTE 240M coefficients (Y' = 0.212 R' + 0.701 G' + 0.087 B'). These coefficients correspond to the SMPTE RP 145 primaries (also known as "SMPTE C") in use at the time the standard was created.

Table in USB Video FAQ

Table 2-6 Matrix of Color Standards and Scenarios
Color Primary
Transfer Function
Luma Matrix
Example Scenario
709
709
709
DVB HDTV Standard Rec.
709
709
601
Typical webcam
240
709
601
NTSC tuner/video capture device
709
709
601
PAL tuner/video capture device
709
240
240
HDTV(1035/60)
170
170
170
DVB 30Hz SDTV
470
*
*
DVD’s
240
470(M)
601
NTSC SDTV
Revision 1.1 June 1, 2005 27
USB Device Class Definition for Video Devices - FAQ
709
470(B,G)
601
PAL SDTV
709
709
709
ATSC (1920/60)
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