ColorBars / ColorBarsHD¶

The ColorBars and ColorBarsHD filters generate a video clip containing SMPTE color bars scaled to any image size. Both filters also generate audio, see the audio section for details.

ColorBars¶

ColorBars produces a video clip containing SMPTE color bars (Rec. ITU-R BT.801-1) scaled to any image size. By default, a 640x480, RGB32, TV range, 29.97 fps, 1 hour long clip is produced.

Syntax and Parameters

ColorBars (int "width", int "height", string "pixel_type", bool "staticframes")

width, height

Set size of the returned clip.

Default: 640, 480

pixel_type

Set color format of the returned clip. May be any of the following: "RGB24", "RGB32", "RGB48", "RGB64", "YUY2", "YV12", "YV16" "YV24", "YV411", or any planar RGBPx, RGBAPx, YUV4xxPx, YUVA4xxPx format.

Default: "RGB32"

staticframes

If set to false, generate all frames. Default true (one static frame is served).

Default: true

ColorBarsHD¶

ColorBarsHD produces a video clip containing SMPTE color bars (Rec. ITU-R BT.709 / ARIB STD-B28 v1.0) scaled to any image size. By default, a 1288x720, YV24, TV range, 29.97 fps, 1 hour long clip is produced.

Syntax and Parameters

ColorBarsHD (int "width", int "height", string "pixel_type", bool "staticframes")

width, height

Set size of the returned clip.

Default: 1288, 720

pixel_type

Set color format of the returned clip. Must be "YV24" or any YUV444Px / YUVA444Px format.

Default: "YV24" (identical to "YUV444P8")

staticframes

If set to false, generate all frames. Default true (one static frame is served).

Default: true

Audio¶

For both filters, an audio tone is also generated. The tone is a 440Hz sine at 48KHz sample rate, 32 bit (Float), stereo. The tone pulses in the right speaker, being turned on and off once every second. Level is 0 dBFS.

You can use Amplify to set a softer level (0dB can be a little deafening!)

ColorBarsHD
AmplifyDB(-20)

Broadcasting organizations usually specify an "alignment tone" accompanying colorbars at anywhere from -12 to -20 dBFS; if sending materials to another party, be sure to get their preferred alignment tone level. The exact level doesn't matter as long as all parties agree to it.

A note on notation¶

This page adopts the ITU style when discussing video levels which might be represented at different bit depths:

“ To avoid confusion between 8-bit and 10-bit representations, the eight most-significant bits are considered to be an integer part while the two additional bits, if present, are considered to be fractional part.

For example, the bit pattern 10010001 would be expressed as 145_d, whereas the pattern 1001000101 would be expressed as 145.25_d. ”

ITU-R BT.601-7 (page 4)

Video levels shown below with the subscript "d" are assumed to be scaled by 2^(bit depth-8). For example, 235_d at bit depth 10 becomes 235 × 2^(10-8) = 235 × 4 = 940.

see Deep Color
see AviSynthPlus color formats

TV range¶

For both filters, in all color formats, luminance levels are TV (limited) range, where black=16_d and white=235_d, within a total possible range of 0-255_d.

The table below shows the TV-range values ColorBarsHD generates, and those same values as they should be after converting to full range.

$\mathtt{Y_\text{full} = (Y_\text{tv}-16_\text{d}) × 255_\text{d}/(235_\text{d}-16_\text{d})}$ // (for R, G, B, Y)

$\mathtt{U_\text{full} = (U_\text{tv}-128_\text{d}) × 255_\text{d}/(240_\text{d}-16_\text{d}) + 128_\text{d}}$ // (for U, V)

$\mathtt{Y_\text{tv} = Y_\text{full} × (235_\text{d}-16_\text{d})/255_\text{d} + 16_\text{d}} \quad$ // (for R, G, B, Y)

$\mathtt{U_\text{tv} = (U_\text{full}-128_\text{d}) × (240_\text{d}-16_\text{d})/255_\text{d} + 128_\text{d}}$ // (for U, V)

Color bar	TV range output						(expanded to full range)
	R	G	B	Y	U	V	R	G	B	Y	U	V
75% White	180_d	180_d	180_d	180_d	128_d	128_d	191_d	191_d	191_d	191_d	128_d	128_d
75% Yellow	180_d	180_d	16_d	168_d	44_d	136_d	191_d	191_d	0_d	177_d	32_d	137_d
75% Cyan	16_d	180_d	180_d	145_d	147_d	44_d	0_d	191_d	191_d	150_d	149_d	32_d
75% Green	16_d	180_d	16_d	133_d	63_d	52_d	0_d	191_d	0_d	136_d	54_d	41_d
75% Magenta	180_d	16_d	180_d	63_d	193_d	204_d	191_d	0_d	191_d	55_d	201_d	214_d
75% Red	180_d	16_d	16_d	51_d	109_d	212_d	191_d	0_d	0_d	41_d	106_d	223_d
75% Blue	16_d	16_d	180_d	28_d	212_d	120_d	0_d	0_d	191_d	14_d	223_d	118_d

These colors are at "75%" of maximum, per common broadcast practice. You may occasionally see "100%" color bars.[1] They are rather useless, as you cannot detect gain or saturation that is too high on a signal that is already at maximum.

PLUGE¶

The lower part of the frame is called the PLUGE (also lowercase: "pluge") signal. From left to right it consists of: -I, white, +Q, then a series of black and near-black bars: 0, -4, 0, +4 and 0 IRE relative to black.

Note 'IRE' is used here to mean 'percent luminance', on a scale from 0 (black) to 100 (white), ignoring the varying broadcast standards where black might be 0 IRE or 7.5 IRE depending on the country.

This section documents the ColorBars pluge only; ColorBarsHD's pluge is similar, but dispenses with -I and +Q.

The table below show the TV-range values ColorBars generates, and those same values as they should be after converting to full range.

PLUGE Element	TV range output						(expanded to full range)
	R	G	B	Y	U	V	R	G	B	Y	U	V
-I	0_d	58_d	98_d	16_d	158_d	95_d	-19_d	49_d	95_d	0_d	162_d	90_d
100% White	235_d	235_d	235_d	235_d	128_d	128_d	255_d	255_d	255_d	255_d	128_d	128_d
+Q	59_d	15_d	126_d	16_d	174_d	149_d	50_d	-1_d	128_d	0_d	180_d	151_d
Black	16_d	16_d	16_d	16_d	128_d	128_d	0_d	0_d	0_d	0_d	128_d	128_d
-4 IRE	7_d	7_d	7_d	7_d	128_d	128_d	-10_d	-10_d	-10_d	-10_d	128_d	128_d
Black	16_d	16_d	16_d	16_d	128_d	128_d	0_d	0_d	0_d	0_d	128_d	128_d
+4 IRE	25_d	25_d	25_d	25_d	128_d	128_d	10_d	10_d	10_d	10_d	128_d	128_d
Black	16_d	16_d	16_d	16_d	128_d	128_d	0_d	0_d	0_d	0_d	128_d	128_d
							(negative values will be clipped to 0)

The -I and +Q bars are vestigial artifacts of NTSC analog TV and are not really used any more.

The -4, 0 and +4 IRE bars can be used to set your monitor brightness – assuming your playback chain expands TV range (16_d-235_d) to full-range (0-255_d) as shown in the images above. The -4 IRE and 0 IRE bars should have the same apparent brightness (they should be as dark as the monitor can display), and the +4 should be a little brighter. If you can see the -4 bar, your monitor brightness is set too high; if you cannot see the +4 bar, your monitor brightness is set too low.[2]

Note, the pluge signal goes out of 16-235_d range in the -I and the -4 bars. These cannot be accurately converted to 0-255_d range.

More information about the colorbars and the PLUGE can be found on the color bars theory page.

Miscellaneous¶

Note, that for example

ColorBars(pixel_type="YUV444P8")

...is equivalent to

ColorBars(pixel_type="RGB32")
ConvertToYUV444(matrix="PC.601")
# "PC.601" / "PC.709" / "PC.2020" don't scale the luma range

When directly generating YUV format data, the color transitions are arranged to occur on a chroma-aligned boundary.

Changelog¶

Version	Changes
AvsiSynth+ 3.4.0	ColorBars: add support for all YUV(A)422 formats and RGB24, RGB48, YV411.
AvsiSynth+ r2487	ColorBars: add support for all YUV(A)444/420, planar RGB(A) formats and RGB64. ColorBarsHD: add support for all YUV(A)444 formats.
AviSynth 2.6.0	Added pixel_type="YV24" to ColorBars. Initial release of ColorBarsHD.
AviSynth 2.5.6	Added `pixel_type` parameter. Added "YUY2" and "YV12" pixel types.
AviSynth 2.5.5	Width and height parameters are now named and optional.

$Date: 2022/04/17 03:58:18 $

ColorBars / ColorBarsHD¶

ColorBars¶

ColorBarsHD¶

Audio¶

A note on notation¶

TV range¶

PLUGE¶

Miscellaneous¶

Changelog¶

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