Yamaha DPX-1100 User Manual download pdf (Page 4)

contrast performance.

My modified “ANSI”

method is designed to

minimize the influence of

room reflections and

other variables that

would affect measure-

ment accuracy. The

modified “ANSI” contrast

ratio of the DPX-1100

measured 390:1, which

is better than CRT projectors, but somewhat

lower than the other HD2+ DLP projectors

I’ve measured (which measured about 600

and 730).

White Field Uniformity

Brightness uniformity on a white-field

test pattern was exceptional. In the highest

contrast, minimum iris aperture mode, the

brightness varied by 10 percent or less at

the sides, top or bottom of the screen, and

12 percent or less in the maximum aperture

mode. The color temperature uniformity var-

ied by 420K in the minimum aperture mode,

and 245K in the maximum aperture mode.

The exceptionally wide range zoom lens

exhibited a small amount of chromatic aber-

ration. Sub-pixel color fringing on white

lines at the edge of the picture was visible

when standing near the screen but wasn’t

noticeable from normal viewing distances.

Color Adjustment

System

The DPX-1100 includes a sophisticated

color management system that permits the

user to individually adjust the chromaticity

of the white reference and each of the pri-

mary (red, green and blue) and comple-

m e n t a ry (yellow, cyan, and magenta) colors.

The Color Adjustment function has three

modes—Standard, WRGB, and WRGBYCM.

The Standard mode provides adjustment of

the white reference, while the native primary

colors are used. The WRGB mode adds

adjustments for the primary colors and

25.3 fL from my screen. The on-off contrast

ratio measured 1960:1. You can also turn on

White Peaking if you want an even brighter

picture for watching sports or other non-crit-

ical viewing in a dimly lit room. With the

White Peaking at its maximum setting, the

projector produced 703 lumens, which is

equivalent to about 32 fL from my screen.

The color temperature increased to 6912K

with a dE value of 10.

The on/off contrast ratio is crucial for

LCD and DLP projectors because it speci-

fies the absolute blackest level in dark

scenes when a projection system is set up

to produce the desired peak-white bright-

ness in bright scenes. A small increase in

the absolute black level severely reduces

shadow detail discrimination in predomi-

nantly dark images. But now that the

absolute black level has reached accept-

able levels in many fixed-pixel projectors, it

is also important to consider intra-field

image contrast. Intra-field contrast is a

measure of the ability to see contrast differ-

ences when there are bright objects in a

scene. The displayable contrast ratio is then

much lower because light from bright

objects will be scattered over the image

obscuring darker objects. The light scatter-

ing occurs within the lens and the optical

system of the projector, but it may also

occur within your home theatre if light

reflects around the room and back onto the

screen.

I use a modified “ANSI” contrast ratio as

a figure-of-merit to characterize intra-field

automatically derives the complementary

colors. The WRGBYCM mode includes

additional adjustments for the complemen-

tary colors.

Color accuracy requires an accurate

D65 gray scale and primary colors that

match the ITU Rec. 601 standard (SMPTE C

primaries) for standard-definition sources,

and the ITU Rec. 709 standard for high-def-

inition video. The primary and complemen-

tary colors are not the same for the two

standards. The color-wheel filters produce a

native primary color triangle that is larger

than either of the video standards, which allows

the effective primary and complementary

colors to be adjusted to match the standard s .

The primary and complementary colors

can be adjusted by directly setting the (x,y)

values in 0.001 increments. A CIE diagram

is displayed in the menu window to select a

color for adjustment. Then the CIE diagram

expands to show the nominal (x,y) position

of the color as it is being adjusted.

When the white reference is selected,

the menu window shows a graph of the

central portion of the CIE diagram. The

white reference is adjusted by setting the

color temperature in 100K increments from

5000K to 10000K, and a ‘uv’ deviation in

0.002 ‘uv’ increments. These are orthogonal

adjustments. The color temperature setting

moves the white reference point along lines

parallel to the blackbody curve, and the ‘uv’

deviation moves the white reference above

or below the blackbody curve along isother-

mal (same temperature) lines. Hence, the

color temperature adjustment sets the

Correlated Color Temperature (CCT), and

the ‘uv’ adjustment sets the vertical position

at the specified CCT. (See the CCT dia-

gram). The hue of the white reference

changes from red to blue as the CCT

increases, and becomes less green and

more magenta as the ‘uv’ value changes

from positive to negative. Both adjustments

have much finer resolution than they did in

the DPX-1000, so it’s now easy to accurate-

ly set the white point to the desired (x,y)

location using a color analyzer.

Red Green Blue Yellow Cyan Magenta

Rec. 601 ‘SD’

x 0.630 0.310 0.155 0.421 0.231 0.314

y 0.340 0.595 0.070 0.507 0.326 0.161

Rec. 709 ‘HD’

x 0.640 0.300 0.150 0.419 0.225 0.321

y 0.330 0.600 0.060 0.505 0.329 0.154

P R I M A RY A N D C O M P L E M E N TA RY C O L O R C H RO M AT I C I T Y

C O L O R A D J U S T M E N T

equipmentReview

www.WidescreenReview.com • Issue 88 • September 2004

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