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contrast ratio, and color accuracy. Measure-

ments were made after adjusting for the

maximum calibrated light output (Contrast

control) with a peak-white PLUGE pattern

(98 IRE stripe against a 100 IRE background),

and the optimum black level (Brightness

control) with a conventional PLUGE pattern.

With the gray scale manually calibrated

to D65, the F5.0 (high contrast)/Low Lamp

mode produced 13.4 fL from my 1.3 gain,

85.3-inch wide, 16:9 Stewart Filmscreen,

which slightly exceeds the 12 foot-Lambert

(fL) SMPTE recommendation for digital cine-

ma. The on/off contrast ratio measured an

exceptional 3005:1, which produced an

absolute black level of just 0.0045 fL when

displaying a 0 IRE (black) field.

The F3.0/Low Lamp mode produced

16.6 fL from my screen, and a still excellent

on/off contrast ratio of 2104:1. That mode

could be used on slightly larger screens if

the F5.0 mode produced too dim of a pic-

ture. The High Lamp mode can also be

used for larger screens, but remember that

a lamp may lose 40 to 50 percent of its light

output over its useful life. So it’s a good idea

to plan your screen size with the Low Lamp

mode, and reserve the High Lamp mode for

use during the latter part of the lamp’s life.

The High Lamp mode increased bright-

ness by about 25 percent. The F5.0 mode

produced 16.9 fL, and the F3.0 mode pro-

duced 20.7 fL from the 1.3 gain screen. The

latter is equivalent to about 454 lumens. If

additional brightness is desired for viewing

sports in a dimly lit room, the High Bright

mode can be enabled. It increased the

brightness about 20 percent, but the color

temperature increased to over 10,000K.

The on/off contrast ratio is extremely

important for DLP and LCD projectors

because it determines the absolute black-

est level in the darkest scenes. A tiny

increase in the black level dramatically

reduces shadow detail discrimination in a

predominantly dark scene. I also find it

objectionable if the “black” background in

an image is noticeably brighter than the

black surrounding the screen.

A distinctly different picture quality factor

is the ability to see contrast differences

when there are bright objects in a scene.

Then the displayable contrast ratio is much

less than the on/off contrast ratio because

light from the bright objects will be scat-

tered over the image obscuring darker

objects. The light scattering occurs within

the lens and the optical system of the pro-

jector, but it may also occur within your the-

atre as light reflects around the room and

back onto the screen.

There is no single measurement that can

precisely describe this intra-field contrast

ratio for all images because it depends on

the size and location of one or more bright

objects within each individual image. Hence

we can only define a figure-of-merit based

on an artificial test pattern. One such figure-

of-merit is the ANSI contrast ratio, which

involves measuring 16 blocks (8 white and

8 black) of a 4 x 4 checkerboard image and

then computing the contrast ratio from the

average luminance of the white and black

blocks. This is laborious and fraught with

practical measurement uncertainties.

I’m using a modified “ANSI” measure-

ment that is the average contrast ratio of the

four central blocks in the 4 x 4 checker-

board. The contrast ratio for each block is

measured separately by fixing the position

and angle of the light meter a few feet in

front of the projector, and then electronically

reversing the black and white blocks of the

checkerboard pattern. This increases the

magnitude of the “black” values to minimize

the influence of room reflections and

improves the computational accuracy. It

also eliminates other issues related to mak-

ing measurements off the screen. Starting

with this issue I will include this modified

“ANSI” contrast ratio measurement in each

projector review. The VP-12S3L measured

604:1. The only other HD2+ DLP projector

that I have reviewed measured 728:1. This

is outstanding performance for both products.

As video levels approach black, dither-

ing noise has been another significant prob-

lem in earlier generation DLP projectors. An

excellent way to look for dithering noise is

to view the 1-10 IRE 10-step luma patterns

from the AccuPel generator. Dithering noise

was visible on the 1 to 3 IRE steps of the

luma pattern when viewed close to the

screen, but it was nearly invisible from a

normal seating distance.

White Field Uniformity

Brightness uniformity on a white-field

test pattern was extraordinary. There was

only a 1 percent variation in brightness from

the top to bottom center of the screen, and

7 percent or less from side to side for both

the F3.0 and F5.0 contrast modes. The

color temperature uniformity was within 70K

over most of the screen, with a variation of

about 230K at one edge in both modes.

Color Accuracy

The CIE x,y diagram shows the 720p

DVI RGB color accuracy compared to the

Rec. 709 (HDTV) colorimetry. The same

measurements are also shown on a CIE

u’,v’ diagram, which provides a more per-

ceptually uniform presentation of the color

space. The projector primaries are slightly

more saturated than the HDTV primaries,

but they are balanced so that the position of

the yellow, cyan and magenta complemen-

tary colors are extremely close to the stan-

dard colors. The hues of flesh tones and the

other colors within the color gamut are quite

accurate and images are brilliantly vivid.

The CIE u’,v’ diagram for the 480i YPbPr

input shows that the complementary color

hues are still extremely accurate, even

though the red primary is a bit farther out-

side the Rec. 601 primary for standard-defi-

nition video. You will likely want to use the

YPbPr (or S-video) input, which provides a

Color control if reds are oversaturated or too

vivid on some video broadcasts or a DVD.

Edge And Detail

Enhancement

The projector includes more than a

dozen adjustments for edge and detail

enhancement that separately affect luma

and chroma portions of the image. The

Luminance submenu in the Fine Menu

includes eight adjustments for the Gain and

Threshold of the horizontal and vertical

Edge and Detail enhancement. The

Chrominance submenu includes additional

adjustments for Horizontal Edge Gain and

Threshold, Vertical Edge Gain, Enhancement,

and Delay. The Enhancement item is only

enabled for composite and S-video signals.

The Threshold adjustments determine the

minimum luma or chroma amplitudes that

the enhancement processing will affect. The

Gain adjustments control how much enhance-

ment is applied to edges or fine details.

The Sharpness control (in the Picture

Adjust menu) acts like a master gain control

for the Luminance enhancement processing. If

the Sharpness control, or all of the Luminance

enhancement gain controls are set to zero,

there is no luma enhancement. As the

Sharpness control is increased, the enhance-

ment increases proportional to the individual

Luminance enhancement gain settings.

The Sharpness control appears to work

more like an on-off switch for the Chrominance

enhancement. If the Sharpness is set to

zero, the Chrominance gain adjustments

seem to have no effect. But if the Sharpness

is set to ‘1’ or higher, the Chrominance gain

adjustments take full effect. When the

Enhancement item is enabled, it appears to

have master control over the Chrominance

gain adjustments.

Even when the Sharpness control and

the other Chrominance gain adjustments

are set to zero, there appears to be some

chroma edge enhancement on the Pb

channel. The leading edge transitions of

blue patches in the Snell & Wilcox pattern

of Video Essentials appear to be shortened,

and the Y/C delay pattern on AVIA: Guide

Equipment

Review

Widescreen Review • Issue 84 • May 2004

Page 4/7

#84 Master Pages 26-49 3/22/04 4:31 PM Page 42

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