Hitachi 42HDT20 16:9 plasma television Calibration
For logistical reasons, the sample measured was different than the one provided to MF, and its initial settings were as received from the factory. The Hitachi 42HDT20's overscan measured 3-4% on all sides. The set's DC restoration was fine, and its DVD resolution of 500 lines per picture height produced an exceptionally crisp image. Oddly, the reds seemed slightly misconverged to the left on test patterns, which shouldn't happen with a fixed-pixel plasma. This was not visible with most regular program material. Using an NTSC source (the Video Essentials test DVD), the phosphor color points revealed a slightly purplish-green blue and a deeper green than standard, though none of these deviations detracted from the set's subjectively excellent color.
Before measuring the contrast and gray scale, I first set the white level (Contrast control) to a setting that did not crush or clip the peak whites, then adjusted the blacks (Brightness control) using Video Essentials' PLUGE pattern (chapter 17-2). This resulted in an output of approximately 24 foot-Lamberts. I then measured the contrast four ways: full on (a 100 IRE white field) to full off (the full black field produced by switching to an open input) measured 171; a white window (VE, chapter 17-32, 100 IRE) to full off measured 239; the ANSI contrast, using a black-and-white checkerboard pattern, measured 104; and, finally, the ratio of a 100-IRE window to the average light output from the black border around it measured 175. For comparison, the plasma with the best blacks I have seen to date, the Fujitsu PDS-5002, produced contrast values of 436 (full white field/full off), 185 (ANSI), and 538 (white window/black border).
I came to the calibration prepared to do the usual service-menu tweaking, but it didn't prove necessary. The curve in the accompanying figure shows what the measured sample of the 42HDT20 produced, as delivered, in the Standard color-temperature setting. This is a remarkably good factory setup. Furthermore, the values were very close to the optimum D6500 across the entire brightness range. Reds were pushed a little; a reduction in the Color brought this into line without unduly desaturating the other colors. At the Medium setting, the temperature was just over 7000K across the board; at High, it drifted up from 8261K at the low end (30 IRE) to 8778K at the high (100 IRE).
After finishing the calibration, I spent a little time watching the Hitachi with conventional DVDs. As MF notes, there was relatively little
to complain about with respect to detail, color, brightness, and geometry. But I was a little more troubled than he about a few aspects of the set's performance. This may relate to the different sample, though it seems more likely due to differences in the program material we used. The Faroudja test DVD revealed a tendency of the set to drop in and out of 3:2 pulldown in the Movie mode, which may have caused the visible motion artifacts I saw with 480i sources. The waving flag and rocking pendulum on the Faroudja disc and the opening scenes in Star Trek: Insurrection, with its difficult pan across the village, had clearly visible jagged edges. MF, too, saw a few artifacts, but, as we both observed, these problems essentially disappeared when a 480p input from a good progressive-scan DVD player was used. Interestingly, I found the scaling on the Hitachi 51SWX20B rear-projection CRT I reviewed in the November 2002 issue to be superior to the 42HDT20's.
The 42HDT20's blacks were reasonably deep. But with the Brightness correctly set using a PLUGE pattern, dark scenes in some films exhibited serious posterization, or abrupt rather than gradual transitions in shadowed areas. For example, many of the facial close-ups in the low-contrast pteronodon sequence in Jurassic Park III looked like paint-by-numbers images. (MF noted this also, but wasn't as bothered by it.) The problem could be minimized by raising the brightness, but this slightly desaturated the image in brighter scenes and sacrificed the depths of blacks in darker ones—something plasmas can't really afford to compromise.—Thomas J. Norton