InFocus TD61, User Manual

Page: 36 / 102

3.3 What Does Colorspace Mean?
34
3.3 What Does Colorspace Mean?
There are many ways to represent a color picture electronically.
RGB
and
YPbPr
are the two most com-
mon in analog and digital sources. The display will accept either.
What does colorspace mean?
There are two types—
RGB
and YPbPr —and they
carry the picture information on three conductors or
wires.
RGB
In
RGB
there are separate conductors (wires) for
red, green and blue. Full white is represented by a
100% signal level on all three conductors. Black is
represented by a 0% level on all three.
Dark red is represented by, say, a 30% level on the
red conductor and 0% on the blue and green.
RGB
signals need sync for horizontal and vertical.
This may be:
• separate sync on two additional conductors
(
RGB
HV ).
• composite sync—H & V sync mixed together—on
a separate conductor (
RGB
S ).
• sync on the green channel (
RGB
).
In this manual,
RGB
refers to all of these types, unless
one of them is specifically called out.
YPbPr
YPbPr also has three conductors.
• The Y conductor carries the luminance (bright-
ness) signal level as well as composite sync. This
luminance (brightness) signal is developed by
combining red, green, and blue in certain propor-
tions: 30% red, 59% green and 11% blue.
• The Pb line carries a signal that represents the
blue component of the picture minus the lumi-
nance component: B–Y.
• The Pr line carries a signal that represents the red
component of the picture minus the luminance
component: R–Y.
YPbPr is sometimes called YUV and sometimes
called component video. DVD players often have a set
of three component video connectors.This makes a
picture of substantially higher quality than the single
conductor Video Out–Video In connection.
Use the correct colorspace
• If the picture is coming from S-Video, Composite
or the Component outputs of a DVD player, the
TD61automatically sets the colorspace.
• For Analog and Digital inputs, colorspace must be
set by the user.
Note: For DVD players outputting component video,
you should use the component input (RCA
connectors). For interlaced signals this will give a better
picture than through the analog input. If the signal is
non-interlaced (or HDTV), you must use the analog
connector.
How does the YPbPr system make green?
At first glance, it may look like the YPbPr system
doesn’t have any way to render something green. But
look beyond first glance.
The Y part of the signal has a green component in
it. Y is made from 59% of the green of RGB, 30% of
the red, and 11% of the blue.
By combining the Y, the B-Y and the R-Y signals
algebraically, it is possible to convert the YPbPr signal
into RGB. This conversion is performed in the elec-
tronics module of the TD61.
When the Colorspace item in the Picture menu is
set for RGB, the electronics module sends the three
colors through to the optical engine without transla-
tion. It is only processed by the Input Level settings
and the Color Balance settings.
When the Colorspace is set to YPbPr, the input
signal is first translated to RGB before it is processed
by the Input Level and Color Balance settings and
sent to the optical engine.
Downloaded from www.Manualslib.com manuals search engine