The plasma Panasonic Viera TC-P46G25 consumes significantly more electricity than a 46-inch LCD HDTV. And though the estimated price of $1100 (as of September 20, 2010) looks good, this television’s image quality was inferior to that of the other three LCD TVs we tested alongside it.

It might have been worse. At PC World Labs, we use professional equipment to calibrate each TV before conducting our image quality tests. But the TC-P46G25’s fine-tuning controls didn’t allow us to turn down the green to an appropriate level, throwing the colors off horribly.

Luckily, the TC-P46G25 has a certified THX preset mode that fell within our parameters, so we tested the TV in that mode. In theory, a THX-certified HDTV like the TC-P46G25 should have superior image quality, and a THX preset mode should negate the need for professional calibration. But the image quality of this set was poor on a range of media. Our selection of broadcast, DVD, and Blu-ray clips showed too much contrast and occasional graininess. It had particular problems with the Phantom of the Opera DVD, in a test of the TV’s ability to upconvert a 480p signal to 1080p. To my eyes, faces had the artificial texture of a bad oil painting. To another judge, image quality was at the level of a VHS tape.

The TC-P46G25 was at its worst on our panning tests. As a still photo of a seaside town moved diagonally (and supposedly smoothly) across the screen, one judge thought the scene looked like an earthquake.

As a plasma set, the TC-P46G25 has one definite image-quality advantage over many LCDs: Its range of good viewing angles is excellent, and its image quality doesn’t degrade as you move to the side.

This Panasonic sounds much better than it looks. I had to turn the volume all the way up to hear even the slightest strain in a loud blast of music. The faux surround sound was a reasonable imitation, though no one would mistake it for the real thing.

You can listen to your own MP3 collection through the TC-P46G25’s speakers by plugging an SD Card or a flash drive into the appropriate inputs. (Most modern TVs have either an SD Card slot or a USB port; the TC-P46G25 is one of the few that has both.) The only audio format that you can play in this way is MP3, but you can view JPEG photos and assorted video formats.

The multimedia offerings have other flaws. If you want to view a slideshow with musical accompaniment, you must endure a confusing process to create a “soundtrack.” And the first flash drive I tried—one that had successfully worked on three other HDTVs I tested—failed on the TC-P46G25. Panasonic has not offered an explanation.

If the entertainment on your SD Card, flash drive, TV stations, or DVD/Blu-ray collection aren’t enough for you, you can plug an ethernet cable into the TC-P46G25 and watch Internet content. (There’s also a Wi-Fi option, but it requires an extra-cost adapter.) Entertainment options include Amazon Video on Demand, Netflix, Picasa, Pandora, Skype, Twitter, and YouTube.

Like most recent Internet-capable HDTVs, the TC-P46G25 provides a YouTube interface that begins by displaying each video in a small window. To change it to full-screen, you have to use the arrow keys to select the small window, and then click OK.

This is the first TV I’ve seen that offers Netflix’s improved interface, which allows you to browse the library and select programs from the TV. No longer do you have to go to a computer to put something into your instant queue.

Overall, the TC-P46G25 has a particularly pleasant and easy user interface, starting with the setup wizard, which provides graphics illustrating what you should press on the remote (which you’re presumably using for the first time). Similarly, the main menu provides a graphic of the remote and brief, useful explanations of the options you select.

Not that everything is perfect. If you select a picture adjustment like Contrast and press OK, nothing happens. You have to press the left of right arrow to hide the menu and then adjust the contrast. And when you’re done, pressing OK doesn’t bring you back to the menu; instead you have to few seconds without pushing any of the remote’s buttons.

The remote is quite large, but it has a nice grip and most of the buttons are large, too. The volume controls, channel controls, and number buttons are well placed and easy to press, but the arrow buttons are a bit high. Press any key on the remote and all of them light up for a few seconds, helping you find what you need in the dark. The remote is not programmable, however.

Plasma TVs use more electricity than LCDs, but the TC-P46G25 manages to eke out Energy Star approval, burning 160 watts on average when in use. In standby mode (that is, turned off), it used so little juice that it didn’t register on our power meter. To save even more power, you can set the TV to turn itself off after 10 minutes without a signal and after 3 hours without remote control activity.

All of the numbers, certifications, and extra features should make the TC-P46G25 a terrific television for the price. But the disappointing image quality takes it down several pegs in comparison to the 46- and 47-inch competition.

[For details on our testing method, and a description of what our lab results mean, read “How we test HDTVs”.]