JVC 1080p Color Accuracy, Hz Input, Deinterlacing, 1080i/p Pixel Perfection, ThEROGERSREPORT

#129 JVC REPRINT:Layout 1 2/7/08 1:54 PM Page 6

ThEROGERSREPORT

JVC® DLA-RS2U 1080p D-ILA® Front Projector

Sharpness, resolution, and color fringing (chromatic aberration) are also a function of lens quality. Focus and convergence were quite good in the central area of the screen, but the red focus was not as good as the blue and green, which resulted is slightly wider red lines at the sides of the screen. Red fringing/misalignment increased over the last eighth of the screen width and reached about a half pixel at the extreme right edge. There was also about a quarter pixel of red panel vertical misalignment across the screen.

Overall, images were not quite as sharp as they are with the best single-chip 1080p DLP projectors, but color fringing on bright edges was rarely visible from normal viewing distances, except on test pat- terns. However, a lens with better color correction would undoubtedly yield some sharpness improvement. It is extremely important to adjust the focus very carefully for best sharpness, and depending on panel alignment it may be possible to reduce potential color fringing by slightly favoring the red focus. There was negligible astigmatism or curvature of field from a 1.75:1 throw ratio.

Color Accuracy

The CIE diagrams show color accuracy for digital YCbCr input

signals compared to the Rec. 709 (HD) and SMPTE-C (SD) colorime- try standards using u’,v’ coordinates, which provide a more perceptu- ally uniform presentation of color space than CIE x,y coordinates.

Each primary is oversaturated compared to the standards, but they are well balanced to produce complementary colors with nearly per- fect hues. (Hue is the angle, and saturation is the distance from the white reference.) The primary colors are more oversaturated com- pared to the SMPTE-C standard-definition primaries because they have a smaller color gamut.

The projector’s Color control can be used to reduce overly vivid colors or fleshtones, but it primarily affects the lightness (brightness) of colors, rather than their saturation. The ideal solution would be a built-in Color Management System (CMS) to allow the user a choice of the SMPTE-C, Rec. 709, or native color gamut. Alternatively, at the 2008 Consumer Electronics Show, JVC demonstrated a new external video processor that includes a CMS tailored specifically for the RS2 (and RS1). They expect to introduce it in the first quarter of this year.

ing for broadcast video in the viewing impressions section. Inverse-telecine deinterlacing for 480i movies is still important

because it will be years before the catalog of available high-definition movies are sufficient to replace our libraries of standard-definition DVDs. Inverse-telecine deinterlacing is an ideal process that con- verts interlaced video transferred from film to progressive video with- out artifacts or loss of resolution if the processor can stay locked onto the video’s 3-2 field pulldown cadence. The Gennum processor han- dled most 3-2 pulldown cadence tests and bad edit tests (disrup- tions in the 3-2 cadence) for 480i and 1080i, but it doesn’t include processing to detect other unusual cadence sequences, such as those used in animation or anime.

I’ve been disappointed with the 480i inverse-telecine deinterlacing of the Gennum GF9351 because it fails to lock onto the AVIA Pro 3-2 motion test pattern during the slowest vertical movement, although it works correctly for faster vertical movement. That is often an indicator that it will not consistently lock onto the scrolling yellow text at the beginning of Star Wars: Episode IV—A New Hope, which was the case in my testing of this projector. Even when it did lock to the 3-2 cadence it produced slightly more line twitter on character edges than an older generation Silicon Image processor, or a standalone Lumagen HDQ video processor.

Conversely, 1080i inverse-telecine deinterlacing worked flawlessly on high-definition movies when I forced an HD DVD player to output 1080i signals for testing purposes. There was no visible line twitter, and vertical detail was sharp and well defined during slow vertical camera movement. However, for normal viewing you should use 1080p signals when available, to avoid unnecessary format conver- sions from 1080p native discs.

24 Hz Input

Judder (irregular stuttering motion) is created when 3-2 pulldown is used to convert 24-frames-per-second film to 60-fields-per-second interlaced video, or 3-2 frame repetition is used to create 60-frames- per-second progressive video from film. Most people become condi- tioned to ignore that jerky motion after years of watching movies on broadcast television. However, some people are greatly disturbed by

“Contrast ratios are improved to unprecedented new heights

... [and] the light output is also impressive.”

The CIE diagrams measured with digital RGB input signals (not shown) are virtually identical to the YCbCr CIE diagrams. The YCbCr to RGB color-decoding matrices are accurate for both standard-defi- nition and high-definition signals. CIE diagrams measured with ana- log RGB and YPbPr signals were also nearly identical, which indi- cates excellent analog signal-channel matching and correct decod- ing matrices.

Deinterlacing

The RS2 uses a Gennum GF9351 VXP™ Image Processor for dein- terlacing and scaling. The 10-bit video processor provides film-mode (inverse-telecine) and per-pixel motion-adaptive deinterlacing for standard-definition and high-definition video. However, 480i motion- adaptive deinterlacing has become virtually irrelevant since most video broadcasting that we are likely to watch in a home theatre is now high-definition. Therefore, I no longer comment on that aspect of projector performance. I’ll discuss 1080i motion-adaptive deinterlac-

6Widescreen Review • Issue 129 • March 2008

this temporal artifact. Even those accustomed to the judder of broad- cast movies are usually quick to appreciate the smoother motion pro- vided by displaying film sources at an integer multiple of the original 24-frame-per-second film rate. Fortunately, movies are stored on HD DVD and Blu-ray Discs with their original 24-frames-per-second film rate, and all current players can now output 1080p24 native video. The RS2 accepts the 1080p24 signals through its HDMI inputs and displays them at an integer multiple of the 24 Hz frame rate to avoid judder. I believe this is so important to reproducing the look of film that I wouldn’t consider purchasing a front projector for a home the- atre without that ability.

1080i/p Pixel Perfection

The RS2 produced spatially “pixel perfect” images from 1080p60, 1080p50, and 1080p24 HDMI signals. No pixels were blanked, and each incoming pixel was precisely mapped to a single projector pixel without scaling. The projector’s Gennum deinterlacing also converted

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