LT-46148 Calibration and Bench Testing

We used Datacolor’s Colorfacts Professional 6.0 software to measure the LT-46148's performance in various modes and color temperature settings.  While we were disappointed with many of the results we got from our measurements during this portion of the review this display actually made some amazing images during our viewing evaluation.  So - unless you plan to only view calibration patterns with the display, I'd highly recommend you make sure you read the whole review before coming to any conclusions about this display. 

We started off by measuring the default color temperature of the various picture modes available utilizing the the 80 IRE pattern from Avia Pro DVD via HDMI 1 input.  (Note: Remember the game setting is not available unless the input you use is named game, so it was not evaluated during this portion of the calibration).  The default for each of the modes below included:  Backlight +63 (the brightest setting); Contrast +63 (highest possible setting); and Color Temperature was set to High.  All modes were skewed toward blue regardless of which mode was selected; but here are what the various modes yield in their default settings:

• Brilliant Mode - 11,051K
  

• Bright Mode - 11,776K
  

• Natural Mode - 11,544K
  

To see if we could get anything closer to the target 6500K we also tested each setting in the Low color temperature setting and got these results. 

• Brilliant Mode - 6,811K
  

• Bright Mode - 7,146K
  

• Natural Mode - 7,053K
  

I know this seems counter intuitive, given these naming options we completely expected to wind up using the Natural setting with the low color temperature, but the numbers do not lie.  So, like all good calibrators we went with the settings that got us closest to 6500K (Brilliant with low temperature setting) and did the rest of our tweaking from that starting point.

Real world contrast on this display was tested with the backlight at full on (63 - the default), half (31), and it's lowest setting (0) and gave pretty impressive results at each of the three picture modes tested.

Brilliant Mode

Backlight Level      Contrast         Luminance

0                             469:1               29.4 fL

31                           1,541:1             139.2 fL

63                           2,842:1            240.5 fL

Bright Mode

Backlight Level      Contrast         Luminance

0                             493:1              37.7 fL

31                           1,571:1             118.5 fL

63                           2,622:1            195.3 fL

Natural Mode

Backlight Level      Contrast         Luminance

0                             583:1              46.97 fL

31                           2,015:1             143.8 fL

63                           3,177:1            231.8 fL

Note:  During our contrast measurements, we noted that anytime we had a black screen up, the LT46148 suffered from very obvious light bleed through.  It was splotchy and showed up over the entire screen.  We rarely noticed it while viewing movies or TV, but it could be an annoyance during very dark scenes.

Utilizing the Avia Pro calibration disk we started trying to dial in the contrast and brightness settings using the needle pulse patterns.  It quickly became obvious that the display could not make blacker than black or whiter than white.  So after going back and forth, we finally settled on the following settings: Contrast - 29, Brightness 45, and the Backlight set to 0.  These settings offered the best all around performance we could get from the display.  We also changed the following default values:  Sharpness - default was set at 31, we reset to 0; Video Noise was set to high, we reset to off.  After we got all our settings tweaked on the Brilliant setting, we took another round of ANSI contrast measurements and lumen readings and got a pretty good real life contrast ratio of 469:1 with luminance reading of 26.94 (at 80 IRE).

The CIE color chart measurements for the Toshiba 46LX177 were not up to what we had been expecting, especially with its claim of xvColor support.  Red and blue are pretty much dead on, but green falls far short.  During my calibration I attempted to see if I could expand this performance utilizing the 6 color processor settings in the video menu.  Regardless of what changes I made, I could only shrink the triangle - never increase it to include more colors. 

Other measurements were also a little disappointing during the bench tests.  The gray scale measurements shows RGB levels set heavy on the blue throughout the IRE range. Green stays pretty steady throughout the range, and red dip slightly from about 30 IRE throughout the rest of the range.

The temperature history shows it starting high (almost 7900K at 40 IRE) and gradually going down as you increase through the IRE scale - though it is always above the 6500K target throughout the range.

The gamma reading  (2.12) came in on the low end of the target range (of 2.2 to 2.5) but still at a pleasing level - very similar, in fact to how a CRT display performs (thought by some to be the model example for gamma). This smooth gamma curve produces a very even transition from bright to dark and makes for a very watchable picture that is carried out by real-world testing and viewing sessions.

Audioholics/HQV Bench Testing Summary of Test Results

Note:  Tests were done at 480i via HDMI input #1. *Smooth 120Hz mode OFF.

The biggest thing that jumped out during our HQV testing was how soft the 480i feed from our Toshiba HD-A2 was on this display.  Based on that I would hesitate to feed this display any source less than 480p via HDMI - it doens't seem to fully support it properly. We should also note that while the film detail test passed with the Smooth 120Hz feature turned Off, when we retested with it On, it failed this test. We also noted artifacts and increased jaggies with the 120Hz feature On during both of the jaggies tests. This has been a continuing problem with high speed refresh rates.