fbcbars — display standard color bars on a framebuffer
fbcbars [-e ] [-f ] [-s ] [-F framebuffer] [-S squarescrsize] [-W scr_width] [-N scr_height]
fbcbars displays a color bar scale on the currently selected framebuffer. The default pattern is the standard SMPTE color bars.
With the
-f
flag, FCC/EBU color bars are made.
The entire screen will contain 8 colors:
100% white, 75% yellow, 75% cyan, 75% green, 75% magenta, 75% red, 75% blue,
and black.
By specifying the
-e
flag, the standard EIA color bars are displayed,
arranged horizontally on screen.
The bottom quarter of the screen will be
-I, 100% white, Q, black.
The upper portion of the screen will be
seven colors at 75% intensity:
grey, yellow, cyan, green, magenta, red, blue.
By specifying the
-s
flag, SMPTE color bars are displayed. This is the EIA pattern
with the upper quarter of the bottom quarter of the screen containing
a reversed and shifted version of the upper pattern, which is very
useful for aligning color demodulators in monitors.
Using a dichroic blue filter,
observe the magenta and cyan bars on the NTSC monitor.
Adjust the phase of the chroma demodulator until they have visually
equal intensity.
At this point, all the other color bars will display the correct chroma.
The environment variable FB_FILE specifies
the current framebuffer; see
brlcad(1).
Alternatively, the framebuffer may be explicitly specified
by using the
-F
flag.
Ordinarily, the requested framebuffer size is the device default.
The
-W scr_width
option specifies the width of each output scanline, in pixels.
The
-N scr_height
option specifies the desired height in scanlines of the display device.
-S squarescrsize
sets both the height and width to the size given.