User`s manual

138 Reference Manual
In the previous equations, X
s
is the source data (Y or U or V), X
d
is
the result (Y or U or V),
α is the alpha blending level which is
defined in bit 2 to bit 0. C
0
is the background color and C
1
is the
foreground color. As there are three channels (YUV), C
0
and C
1
could be programmable from C-Bus for every channel.
So there are two ways to change the OSD color:
1. Change the YUV value in Fix_setting.txt
// osd setting
osdcfg.DoOSD = 1
osdcfg.OSDyc0 = 0
osdcfg.OSDyc1 = 255
osdcfg.OSDuc0 = 0
osdcfg.OSDuc1 = 128
osdcfg.OSDvc0 = 0
osdcfg.OSDvc1 = 128
2. Change the alpha blending level (a) as the above algorithm def-
inition.
Refer the following YUV to RGB converting algorithm for detail.
Y = 0.299R + 0.587G + 0.114B
U = - 0.147R- 0.289G + 0.436B
V = 0.615R - 0.515G - 0.100B