ColorBars
Contents |
ColorBars ( [ int width, int height, string pixel_type ] )
ColorBars ( [ int width, int height, string pixel_type, bool staticframes ] )AVS+
Produces a video clip containing SMPTE color bars (Rec. ITU-R BT.801-1) scaled to any image size.
By default, a 640×480, RGB32, TV range, 29.97 fps, 1 hour long clip is produced.
- int width = 640
- int height = 480
- Set size of the returned clip.
- string pixel_type = "RGB32"
- Set color format of the returned clip.
- May be any of the following: "YUY2", "YV12", "YV24" (v2.60), or (default) "RGB32".
- AVS+ "RGB32", "RGB64", "YUY2", or any planar RGB, 4:2:0 or 4:4:4 format.
- bool staticframes = true
- AVS+If set to false, generate all frames. Default true (one static frame is served)
ColorBarsHD ( [ int width, int height, string pixel_type ] )
ColorBarsHD ( [ int width, int height, string pixel_type, bool staticframes ] )AVS+
Added in v2.60, 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 1288×720, YV24, TV range, 29.97 fps, 1 hour long clip is produced.
- int width = 1288
- int height = 720
- Set size of the returned clip.
- string pixel_type = "YV24"
- Set color format of the returned clip. Must be "YV24".
- AVS+ "YV24" or other 4:4:4 format.
- bool staticframes = true
- AVS+If set to false, generate all frames. Default true (one static frame is served)
TV range
For both filters, in all color formats, luminance levels are TV range, where black=16
and white=235, within a total possible range of 0-255.
The table below show the TV-range values ColorBarsHD generates, and those same values as they should be after converting to full range.
- Yfull = (Ytv-16) × 255/(235-16) // (for R, G, B, Y)
- Ufull = (Utv-128) × 255/(240-16) + 128 // (for U, V)
- Ytv = Yfull × (235-16)/255 + 16 // (for R, G, B, Y)
- Utv = (Ufull-128) × (240-16)/255 + 128 // (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 180 180 180 180 128 128 191 191 191 191 128 128 75% Yellow 180 180 16 168 44 136 191 191 0 177 32 137 75% Cyan 16 180 180 145 147 44 0 191 191 150 149 32 75% Green 16 180 16 134 63 52 0 191 0 137 54 41 75% Magenta 180 16 180 63 193 204 191 0 191 55 201 214 75% Red 180 16 16 51 109 212 191 0 0 41 106 223 75% Bue 16 16 180 28 212 120 0 0 191 14 223 118
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 58 98 16 158 95 -19 49 95 0 162 90 100% White 235 235 235 235 128 128 255 255 255 255 128 128 +Q 59 15 126 16 174 149 50 -1 128 0 180 151 Black 16 16 16 16 128 128 0 0 0 0 128 128 -4 IRE 7 7 7 7 128 128 -10 -10 -10 -10 128 128 Black 16 16 16 16 128 128 0 0 0 0 128 128 +4 IRE 25 25 25 25 128 128 10 10 10 10 128 128 Black 16 16 16 16 128 128 0 0 0 0 128 128 (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 (16-235) to full-range (0-255) 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 range in the -I and the -4 bars. These cannot be accurately converted to 0-255 range.
More information about the colorbars and the PLUGE can be found on the colorbars theory page.
High bit depth
AVS+For higher bit depths, the values given above are scaled appropriately – for example:
Color 8-bit 10-bit 16-bit Super-black 0 0 0 Black 16 64 4096 U, V null 128 512 32768 White 235 940 60160 Super-white 255 1023 65535
Audio
For both filters, an audio tone is also generated. The tone is a 440Hz sine at 48KHz sample rate, 16 bit, 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.
Miscellaneous
- Note, that for example
ColorBars(pixel_type="YUY2")
- ...is equivalent to
ColorBars(pixel_type="RGB32") ConvertToYUY2(matrix="PC.601") # "PC.601" / "PC.709" don't scale the luma range
- When directly generating YUV format data, the color transitions are arranged to occur on a chroma-aligned boundary.
Changes
v2.60 |
|
v2.56 | Added pixel_type="YUY2"/"YV12". |