Mitsubishi LT-46148 LCD HDTV - On the Test Bench
This portion of the review details how the Mitsubishi LT-46148 LCD HDTV performed on the test bench. Please read the Mitsubishi LT-46148 LCD HDTV Review Essentials, if you have not already. Below Black Video RGB 0-255 can't pass below black because black is 0. Unfortunately the same goes for YPbPr 16-235 yet with that video signal black is 16 so it could if designed to do so. Bottom line, no below black signals will pass.
While not a severe error, it is one that Videophiles should take note of since some small portion of consumer video content will exceed 16 or 235 by a few notches and an ISF calibration would setup a display to account for that anomaly. This one can't for black.
Using the SMPTE RP133 pattern from DVE the 1920 and 960 boxes clearly showed a blue shift along with the 1080 box showing the same although less in level. This is HDMI YPbPr so the display has a component processing chroma error even though it passed the luminance correctly.
Using that same pattern output as component YPbPr 1080i there was no chroma error but the 1920 response was lower in contrast level. Over Scan Using the Full Native aspect ratio there was 0 over scan. If the digital input you are using is labeled as PC this will activate a different set of aspect ratios, one being 1:1 pixel mapped centered output for scan rates below 1920x1080 with 0 overscan.
Per the owners manual it supports 9 different pixel matrices. In testing with a Sencore VP403 set for PC Mac 640x480 and 1024x768 was not pixel mapped. I also tried the HDTV section at 480p and was greeted with a correct 16:9 aspect ratio. All three of these displayed quite well without any ringing in any of the bursts although they were not pixel mapped.
Only the HDTV 720p, 720x1280, pixel mapped as a centered output. Color Resolution Using HDMI via the Accupel Burst pattern encoded as 4:4:4 color at 720p with the display input label set for PC provided the correct response.
Setting the input label for another input type takes it out of 4:4:4 color mode. Using the same pattern at 1080I the response was OK. As resolution increased color saturation decreased. 120 lines was well saturated, 240 showed a drop, 480 was greatly reduced, 960 was barely noticed and of course 1920 was missing in action as it should be rather than creating a chroma error since HDTV is limited to 960 or half of luminance.
Using component via the Accupel Burst pattern encoded as 4:4:4 color at 1080i the response varied. The 480 line response was actually more saturated than either the 240 or 960 line response. The 960 line response faired better in saturation than HDMI. The 1920 line response was completely saturated, an error, but video YPbPr is limited to 960 lines so this should not be a problem.
Either response is a case of choose your poison since either input type comes with errors. My preference would be HDMI. DVI RGB versus HDMI YPbPr Video Levels Typically any DVI input will be setup for RGB at the source and this display is designed specifically for DVI PC video levels, 0-255 when ever any digital RGB video signal is used. Conversely an HDMI source is typically digital YPbPr and uses consumer video levels 16-235.
According to the manual you must name the HDMI input you are using for your computer, PC, "It is important to use the name PC so that the TV can process the video signal correctly". This will change the formatting or aspect ratio options along with color resolution and response but it will not adjust the video levels back and forth from consumer video 16-235 to PC video 0-255.
Component YPbPr yielded the correct response. Calibration, Test Results and Factory Settings The factory service menu is extremely limited from the controls offered to how they affect the image. The bad news is this display does not favor ISF display calibration one bit.
The display offers three factory presets that change overall response, BRILLIANT, BRIGHT and NATURAL along with two color temperature settings of HIGH and LOW. The good news is selecting NATURAL and LOW yields some very good results. While not accurate these settings provide a decent response envelope as you will see.
BRILLIANT, as with all displays, represents the out of box sales mode settings from the manufacturer to compete against others and induce your purchase. This is the setting you will likely encounter at the retailer when shopping. BRILLIANT pumps up the gamma and expands the color space to its maximum. BRIGHT pumps up the gamma providing correct color space. Only NATURAL provides nearly correct gamma and color space.
Gamma for BRILLIANT and HIGH color temp 0 IRE - NA 10 IRE - 3.2 20 IRE - 3.3 30 IRE - 3.3 40 IRE - 2.5 50 IRE - 2.0 60 IRE - 2.2 70 IRE - 1.5 80 IRE - 1.3 90 IRE - 1.2 100 IRE - end To provide artificially dynamic images the BRILLIANT gamma is setup to expand the black and the natural consequence is the crushing of white.
This leads to video processing artifacts related to pixilation along with a flat dynamic response from 70 to 100 IRE as noted in the review. Gamma for NATURAL and LOW color temp 0 IRE - NA 10 IRE - 2.2 20 IRE - 3.0 30 IRE - 2.9 40 IRE - 2.4 50 IRE - 2.2 60 IRE - 2.2 70 IRE - 2.1 80 IRE - 2.2 90 IRE - 2.2 100 IRE - end While still climbing strongly out of black at the 20 and 30 IRE points the rest of the response is text book.
Like lamp based front or rear projection displays LCD technology has no issue with this and maintains the same response regardless of IRE levels or the amount of screen area provided for reproduction. This is one area of performance where plasma technology suffers dramatically.
Delta C is provided instead which shows how far off from D65 the response is. The target is less than 1. Less than. 5 error is considered quite good approaching a reference response. RGB response charts are included providing a much better understanding of response errors. Delta C for BRILLIANT and HIGH color temp RGB for BRILLIANT and HIGH color temp As expected the grayscale response is heavily shifted towards blue which also significantly shifts all color information towards blue.
Delta C for NATURAL and LOW color temp RGB for NATURAL and LOW color temp For grayscale calibration the product "appears" to be limited to RGB gain controls only for peak white and does not include necessary controls for peak black. The obvious problem is the sloped red response. Trying to calibrate the product I found out that the gain controls do not function as a calibrator would expect.
I tried to flatten out the red but all the gain control does is move that response up or down as is in its entirety. In the world of grayscale calibration we would not call this a gain control yet as an engineer, using the word gain is correct in the generic sense of any electronic adjustment. The controls we are looking for are in there somewhere but Mitsubishi, as usual for many years now, has decided to lock them out.
The response is what it is and ISF calibration can't do anything for this aspect of performance. The human eye is more sensitive to color at peak black rather than peak white so ultimately it is set for the best overall response. That is not a passing grade though because the response you see did not happen by accident, it is calibrated, and the only reason to leave it with these errors is that a correct response reduces light output.
It is possible to have correct color space and incorrect color decoding. Decoding is tested using patterns that provide complex phase angles. The display does not provide any red, green or blue gating feature to properly test this response. Overall decoding via HDMI is quite good using the NATURAL setting if not spot on except for magenta. Via component YPbPr the errors increase slightly. HDMI has the better response.
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Keywords:color, color space, color temp, color decoding, brilliant color, low color, bt color, havoc color, color response, color temperature