SMPTE color bars
SMPTE color bars are a
A precursor to the SMPTE test pattern was conceived by Norbert D. Larky (1927–2018)
An extended version of the SMPTE color bars, SMPTE RP 219:2002[15] was introduced to test HDTV signals (see subsection).[16]
Although color bars were originally designed to calibrate analog NTSC equipment, they remain widely used in transmission and within modern digital television facilities. In the current context color bars are used to maintain accurate chroma and luminance levels in CRT, LCD, LED, plasma, and other video displays, as well as duplication, satellite, fiber-optic and microwave transmission, and television and webcast equipment.
In a survey of the top standards of the organizations' first 100 years, SMPTE EG-1 was voted as the 5th-most important SMPTE standard.[17]
SMPTE ECR 1-1978 (SDTV)
In a SMPTE
Below the main set of seven bars is a strip of
The bottom section contains a square of 100% intensity white and a rectangle of 7.5% intensity black, for use in setting the luminance range. More modern versions of the pattern feature a
These bars give rise to the former portion of the casual term bars and tone. Typically, a
Analog NTSC
Values of 75% (75/7.5/75/7.5) SMPTE ECR 1-1978 color bars as analog NTSC signals:[19][20][21][22]
Color | Luma | Chrominance Range | Chrominance Phase | ||
---|---|---|---|---|---|
IRE | mV | IRE p-p | mV p-p | ° | |
Gray
|
76.9 | 549.1 | 0.0 | 0.0 | - |
Yellow | 69.0 | 492.6 | 62.1 | 443.3 | 167.1° |
Cyan | 56.1 | 400.9 | 87.7 | 626.6 | 283.7° |
Green | 48.2 | 344.5 | 81.9 | 585.2 | 241.3° |
Magenta | 36.2 | 258.2 | 81.9 | 585.2 | 61.3° |
Red | 28.2 | 201.7 | 87.7 | 626.6 | 103.7° |
Blue | 15.4 | 110.1 | 62.1 | 443.3 | 347.1° |
-I | 7.5 | 53.6 | 40.0 | 285.7 | 303.0° |
White | 100.0 | 714.3 | 0.0 | 0.0 | - |
+Q | 7.5 | 53.6 | 40.0 | 285.7 | 33.0° |
Super-black | 3.5 | 25.5 | 0.0 | 0.0 | - |
Black | 7.5 | 53.6 | 0.0 | 0.0 | - |
4% Above Black Level | 11.5 | 81.5 | 0.0 | 0.0 | - |
Note:
Values sourced from the Tektronix TSG95 test pattern generator manual[22]
Digital video
For digital video sources, the 10-bit YCbCr values for SD color bars[23] are based on the SMPTE formula for Y from the NTSC system (Y = 0.299R + 0.587G + 0.114B).[24] The following table show the expected digital values, for example when measured using a signal analyzer.[25]
10-bit YCbCr values for SD 75% color bars | |||
---|---|---|---|
Color | Y | Cb | Cr |
White | 940 | 512 | 512 |
Yellow | 646 | 176 | 567 |
Cyan | 525 | 625 | 176 |
Green | 450 | 289 | 231 |
Magenta | 335 | 735 | 793 |
Red | 260 | 399 | 848 |
Blue | 139 | 848 | 457 |
Black | 64 | 512 | 512 |
Note: Values sourced from "Leader Teleproduction Test Volume 3 Number 4 - Digital Video Levels"[24]
The colors below are presented using sRGB transfer of CSS. Since sRGB is the standard colorspace for webpages and computer screens, this gives only an idea of the intended colors. They are not completely representative of how they look on TV displays, since these follow the ITU-R BT.1886 standard, specifying a different gamma correction value, and thus colors below will look darker on such a display, and those darker colors will be the reference ones. The off-by-one errors (for example 254 instead of 255 and 1 instead of 0) happen because the 8 bit Y'PbPr values were used when decoding to R'G'B', if you use 10-bit Y'PbPr that does not happen.
COLOR | 8-bit Studio R'G'B' |
10-bit Studio R'G'B' |
8-bit Y'PbPr
|
10-bit Y'PbPr | 12-bit Y'PbPr |
---|---|---|---|---|---|
40% Gray | 104-104-104 | 414-414-414 | 104-128-128 | 414-512-512 | 1658-2048-2048 |
75% White | 180-180-180 | 721-721-721 | 180-128-128 | 721-512-512 | 2884-2048-2048 |
75% Yellow | 180-180-16 | 721-721-64 | 168-44-136 | 674-176-543 | 2694-704-2171 |
75% Cyan | 16-180-180 | 64-721-721 | 145-147-44 | 581-589-176 | 2325-2356-704 |
75% Green | 16-180-16 | 64-721-64 | 133-63-52 | 534-253-207 | 2136-1012-827 |
75% Magenta | 180-16-180 | 721-64-721 | 63-193-204 | 251-771-817 | 1004-3084-3269 |
75% Red | 180-16-16 | 721-64-64 | 51-109-212 | 204-435-848 | 815-1740-3392 |
75% Blue | 16-16-180 | 64-64-721 | 28-212-120 | 111-848-481 | 446-3392-1925 |
75% Black | 16-16-16 | 64-64-64 | 16-128-128 | 64-512-512 | 256-2048-2048 |
100% White | 235-235-235 | 940-940-940 | 235-128-128 | 940-512-512 | 3760-2048-2048 |
+Q | 72-16-118 | 288-64-472 | 35-174-152 | 141-697-606 | 564-2787-2425 |
+I | 106-52-16 | 424-208-64 | 61-103-157 | 245-412-629 | 982-1648-2516 |
-I | 16-70-106 | 64-280-424 | 61-153-99 | 244-612-395 | 976-2448-1580 |
The source data for 10-bit and 12-bit Y'PbPr is 8-bit Studio R'G'B', so 10-bit data is not just a bitshift operation (that means multiply by 4) from 8-bit Y'PbPr, as usually the case. For example, for 75% Blue 28-212-120 would be just 112-848-480, but it is actually 111-848-481.[27]
Per ITU-R BT.2111-2 TABLE 2
SMPTE RP 219:2002 (HDTV version)
An extended version of SMPTE Color Bars signal, developed by the Japanese
Digital test images generated following the RP 219:2002 specifications and adapted to perfectly fit 114 standard and non-standard resolutions for both 16bpp and 8bpp, are freely available in the COLOR dataset of the TESTIMAGES archive.[16]
Later RP 219:2002 became RP 219-1:2014, with RP 219-2:2016
Values
The values of 100% (100/0/100/0) SMPTE RP 219:2002 color bars (1.00 * 219 + 16 = 235) using BT.709 matrix coefficients (only white and black are the same using BT.601 matrix), taken from the standard:
COLOR | 8-bit Studio R'G'B'
|
8-bit Y'PbPr
|
10-bit Y'PbPr | 12-bit Y'PbPr |
---|---|---|---|---|
100% White | 235-235-235 | 235-128-128 | 940-512-512 | 3760-2048-2048 |
100% Yellow | 235-235-16 | 219-16-138 | 877-64-553 | 3507-256-2212 |
100% Cyan | 16-235-235 | 188-154-16 | 754-615-64 | 3015-2459-256 |
100% Red | 235-16-16 | 63-102-240 | 250-409-960 | 1001-1637-3840 |
100% Blue | 16-16-235 | 32-240-118 | 127-960-471 | 509-3840-1884 |
100% Black | 16-16-16 | 16-128-128 | 64-512-512 | 256-2048-2048 |
ITU-R Rec. BT.1729[32] specified the last two 100% colors, green and magenta. It also specified all 100% colors for BT.601 matrix, not only BT.709.[22]
See also
- Captain Midnight broadcast signal intrusion
- EBU color bars
- China Girl (filmmaking)
- Indian-head test pattern
- Test Card F
- 2-pop
- Philips PM5544
References
- ISBN 978-1-61482-000-0.
- ^ NTSC and NTSC/PAL/SECAM Test/Sync Generators (PDF). Leader.
- ^ Model 408NPS INSTRUCTION MANUAL (PDF). Leader. p. 5.2.
- ^ CG-931/2 - Color Pattern Generator (PDF). Kenwood. p. 16. Archived from the original (PDF) on 2022-07-27. Retrieved 2022-07-27.
- ^ "Norbert David Larky Obituary (1927 - 2018) Los Angeles Times". Legacy.com.
- ^ "The History of TV Color Bars, One of the First Electronic Graphics Ever Made". www.vice.com. 20 July 2020.
- ^ "David D. Holmes Obituary (2006) The Times, Trenton". Legacy.com.
- ^ "Email from The Inventor of Color Bars". March 30, 2009.
- ^ US patent 2742525, Norbert D. Larky, Somerville & David I. Holmes, New Brunswick, N.J., "Color Test Pattern Generator", issued April 27, 1956, assigned to Radio Corporation of America
- ^ "CTA - EIA-189 Encoded Color Bar Signal". Standards.globalspec.com.
- ^ Hank Mahler, developer of the SMPTE color bars, passes away, from TVTechnology.com, October 13, 2021
- ^ "Danbury CT Funeral Home and Cremation Center | Danbury Memorial Funeral Home and Cremation Service LLC".
- ^ Goldberg, A. A. (June 30, 1977). "A Monitor Alignment Color Bar Test Signal" (PDF). Proceedings, 31st Annual Broadcast Engineering Conference, National Association of Broadcasters. 31: 84–85.
- ^ "Outstanding Achievement in Technical/Engineering Development Awards" (PDF). National Academy of Television Arts and Sciences. 2009-03-26. Archived from the original (PDF) on March 26, 2009. Retrieved 2018-05-25.
- ^ ISBN 978-1-61482-230-1.
- ^ a b "TESTIMAGES". Testimages.org.
- ^ Howard Lukk. "Countdown to History – 100 Years of SMPTE Standards Development". Us9.campaign-archive.com.
- ISBN 978-1-61482-000-0.
- ^ "SMPTE 170M-2004 - Television - Composite Analog Video Signal - NTSC for Studio Applications". standards.globalspec.com. SMPTE. p. 18.
- ISBN 0-7506-7822-4.
- ^ "Kenwood CG-960, CG-950, and CG-930 Series Color Pattern Generators" (PDF). Kenwood. p. 171. Retrieved 28 February 2022.
- ^ a b c "Tektronix TSG95 Pathfinder PAL-NTSC Signal Generator" (PDF). p. 39. Retrieved 28 February 2022.
- ^ DIGITAL VIDEO LEVELS (PDF). Leader Instruments Corporation. Archived from the original (PDF) on 2022-02-22.
- ^ a b Teleproduction Test Volume 3 Number 4 - DIGITAL VIDEO LEVELS (PDF). Leader Instruments Corporation. p. 6. Archived from the original (PDF) on 2022-02-22.
- ^ "LV 5100D/LV 5100D - COMPONENT DIGITAL WAVEFORM MONITOR" (PDF).
- ^ "Color Calculator". Res18h39.netlify.app. Retrieved 2021-04-15.
- ^ a b "Color Bars – Reference Levels – VideoQ Tech Blog". Blog.videoq.com. 28 October 2018. Retrieved 2021-05-11.
- ISBN 978-1-68303-057-7.
- ^ "Overview of ARIB Standards (STD-B66)|Association of Radio Industries and Businesses". www.arib.or.jp. Retrieved 2023-07-21.
- ^ Recommendation ITU-R BT.2111-2 (PDF). ITU-R. 2020.
- ^ Colour Bar Test Pattern for Hybrid Log-Gamma (HLG) High Dynamic Range Television (HDR-TV) System - ARIB STD-B72 (PDF). ARIB. 2021.
- ^ Recommendation ITU-R BT.1729 - Common 16:9 or 4:3 aspect ratio digital television reference test pattern (PDF). ITU-R. 2005.