Yamaha DPX-1100 User Manual download pdf (Page 5)

The WRGB and WRGBYCM modes are

factory preset with the Rec. 709 high-defini-

tion primary colors. Yamaha should include

the Rec. 601 color values as another preset

choice, but you can enter them yourself. It

is rather complex to compute the (x,y) coor-

dinates of the complimentary colors, so I

created a table for you with all of the (x,y)

color coordinates for Rec. 601 and Rec.

709. A gain (brightness) adjustment is also

provided for each color. The DPX-1100 can

automatically adjust the gain of the individ-

ual colors, or they can be manually set using

the red, green, and blue filters supplied with

the AVIA: Guide To Home Theater or Digital

Video Essentials.

The DPX-1100 Color Adjustment system

is an exceptional feature. It is easy to direct-

ly enter values for a colorimetry standard

(i.e. Rec. 601), or to use a color analyzer to

adjust the values to optimize their accuracy.

But it’s cumbersome to manually copy all of

the entries from one memory to another if

you use multiple inputs. A memory-to-mem-

ory copy function would solve the problem,

or the Color Adjustment values could be

saved in global memories that could later

be assigned to specific input memories.

Gray Scale Accuracy

The Color Adjustment function provides

the means to adjust the white reference at a

single video level. To achieve accurate

color reproduction, the white reference must

ideally remain at D65 for all brightness lev-

els from 0-IRE (black) to 100-IRE (peak

white). That ability is called gray scale

tracking. Most projectors provide gray

scale-tracking controls (RGB offset and

gain) that apply to all input signals. The

DPX-1100 only provides those controls

(Level Adjustments) for analog RGB signals,

and relies on fixed parameters to provide

acceptable gray scale tracking for HDMI

and other analog signals. Fortunately, the

DPX-1100 gray scale tracking still per-

formed very well. (Level Adjustments are

also provided for analog YPbPr signals, but

those only affect color decoding and not

grayscale accuracy.)

I tested the HDMI input first. I used the

Color Adjustment function to set the color

temperature to 6500K, and because D65 is

just above the blackbody curve I set the ‘uv’

value to +0.002. I was pleasantly surprised

when the 75-IRE gray window measured

(x=0.314, y=0.329), which is almost exactly

the x,y coordinates (0.313, 0.329) of D65.

But I was even more pleased that the gray

scale measured 6500K +144/-130K from

20-IRE to 100-IRE, and most importantly the

dE value was 2 or less over most of the

gray scale range and only 6 at 10 IRE. The

dE value expresses the distance from D65

in a color space that is perceptually more

uniform than the CIE x,y color space. A dE

value of 1 is the just noticeable difference

(JND), but values of 3 or less are negligible

differences in most practical situations.

The analog YPbPr input also produced

good gray scale tracking. The dE value was

2 or less over most of the grayscale range,

increasing to 4 at 100-IRE and 6 at 10 IRE.

These results are included in the Gray Scale

Tracking table. You can see in the chart that

color temperature alone is a fairly poor indi-

cator of gray scale accuracy. The 100-IRE

color temperature is much closer to 6500K

for the YPbPr input compared to the HDMI

input, but the perceived color error is larger

(dE of 4 versus 1).

I used the Level Adjustments that are

provided for analog RGB signals to improve

the gray scale tracking at the darker levels.

The dE value at 10-IRE improved from 6 to

3. I could also have improved the tracking

at 100-IRE (dE = 4) by reducing the peak

white output slightly, but I was already

pleased with the results. My calibrated set-

tings for the analog RGB input measured

6500K +22/-70K from 10-100 IRE, and had

the best overall dE performance.

Color Accuracy

All of the primary and complementary

color measurements in this section were

made after setting the white reference to

D65 at 75 IRE, but without calibrating the

individual colors with a color analyzer.

In the “Standard” Color Adjustment

mode, the DPX-1100 native primary colors

extend beyond the Rec. 601 and Rec. 709

primaries. This produces extremely vivid

colors, but reds and greens appear oversat-

urated, particularly with standard-definition

sources. The first CIE diagram shows that

the native green and red primaries lie well

outside the Rec. 709 high-definition primaries.

The WRGB and WRGBCYM modes are

f a c t o ry preset to the Rec. 709 high-definition

primaries. The second CIE diagram was

produced with 720p digital RGB signals. It

shows an excellent match, with the Rec. 709

HDTV standard colors without any additional

calibration with a color analyzer. Measure m e n t s

with 720p digital YCbCr signals produce

the same CIE (x,y) values within 0.001,

which indicates that there is negligible error

in the high-definition YCbCr/ YPbPr color

decoder. I also repeated the measurements

with analog 720p YPbPr signals, and again

all of the CIE (x,y) values agreed within

0.001. This is superb performance that indi-

cates that the analog A/D converters are

precisely calibrated to produce negligible

error in the analog video signal path.

Next, I manually entered the Rec. 601

primary and complementary color coordi-

nates into the WRGBCYM settings. The third

CIE diagram was produced with 480p digi-

tal YCbCr signals. It shows an excellent

match with the Rec. 601 standard-definition

colors. The same measurements taken with

480p digital RGB signals exactly re p ro d u c e d

the same effective primary colors, and the

largest deviation in a complementary color

was only 0.003. Each color can be individu-

ally calibrated with a color analyzer, but the

visual differences in the image were nearly

insignificant.

Scaling And Overscan

The DPX-1100 includes a new feature

that gives the user a choice of two overscan

modes. In the Standard mode, I measured

about 2.5 to 4 percent overscan on each

edge of the frame, for each of the analog

and digital signal formats. The overscan

measurements below are for the Full mode,

which is intended to produce frames with

no overscan.

Except for some blanking along the

edges of the frame, the DPX-1100 produces

a spatially ‘pixel perfect’ image when its

HDMI input is driven by 720p digital video

signals. When the Sharpness control is off,

each visible pixel from the source is pre-

cisely mapped to a single projector pixel,

without scaling or edge enhancement.

There is no edge outlining on horizontal or

vertical lines, which are displayed with pre-

cisely the pixel widths or thickness pro-

duced by the source. The single pixel verti-

cal lines within the high frequency multi-

burst pattern are rendered as single pixel

lines with full contrast. However, there are

two blank pixel columns (vertical lines) on

both the left and right sides of the screen

and four blank pixel rows (horizontal lines)

at the bottom of the screen. There are no

horizontal or vertical position adjustments

for HDMI (or DVI) signals to make the blank

pixels visible.

The scaling was exceptional for 480i,

480p, and 1080i signals. With the AccuPel

generator set to produce video-edge transi-

tion rates, there was no visible edge outlin-

ing around 1080i vertical lines, and outlining

around 480i and 480p vertical lines was so

faint that it could barely be detected when

standing within a few feet of the screen.

There was only about one pixel of outlining

above and below 1080i horizontal edges

and only two pixels for 480i and 480p hori-

zontal edges. Digital video signals from set-

top boxes or DVD players will be similarly

transition-rate limited for movies or other

broadcast video sources. With faster PC-

edge transitions (analog or digital signals)

equipmentReview

Widescreen Review • Issue 88 • September 2004

Page 5/7

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Yamaha DPX-1100 User Manual Page 5

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