JVC LT-32P679 LCD HDTV Review - Performance: Color

We were not impressed by the JVC LT-32P679's performancein our color tests. We saw significant problems with the color temperature of white as it approached black, with a distinct bluish tinge. We also saw problems with the accuracy of red, green and blue colors at higher intensities. We also saw significant error in the range of colors the HDTV was able to produce. Not a good performance.

Color Temperature (6.53)
Whites on HDTVs can vary depending on the intensity of the color, ranging from brightest white to black. What you want from your white is for it to stay stable regardless of the intensity. You don't want to see it get a bluish or yellowish cast as the intensity varies. Below you can see the graph of the JVC LT-32P679's performance in our color temperature test. Along the x axis are all the intensities of white and along the y axis are the measured color temperatures at each intensity.

As you can see the JVC LT-32P679 shows some significant variation in color temperature, especially as the intensity of the white goes down. To judge how serious this variation is we look at another chart, displayed below. Here we look at all of the data points on a graph of color. Any data point that falls within the red circle is not significant enough to be visible by the human eye. Points outside the circle are visible by the human eye.

You can see from this chart that the vast majority of variation in color temperature for the JVC LT-32P679 were not visible to the human eye. Those that are were mostly related to significant shifts in color temperature as whites approached black, as we saw on the first chart above. This variation was very significant and what it means to the viewer is that daker greys will appear with a strongly bluish cast. It this extreme variation in the dimmer whites that contribute the most to the JVC LT-32P679's relatively poor performance in this test.

RGB Curve (7.06)
All the colors displayed by your HDTV are made up of combinations of Red, Blue and Green, so how accurately these are displayed is very important to how well your HDTV displays all colors. In this test we look at how accurately the JVC LT-32P679 displays incoming signals for a range of intensities of Reds, Blues and Greens. Our test produces the following curves for each of the three primary colors.

On a perfect display each of these curves would be smooth and slightly curved from the bottom left to the top right. You can see that the JVC LT-32P679's performance does not match this ideal. In particular all three colors start to lose the ability to differentiate between different intensites at the higher range, with blues performing the worse in this area as evinced by the flat top. Both reds and greens have their problems as well however as they begin to flatten at higher intensities.

What this means in practice is that you'll lose detail in colors at higher intensities with the JVC LT-32P679. For example we have a photo of a marching band wearing bright red uniforms. On the JVC LT-32P679 these uniforms appeared flat and lacked detail. In addition we also noticed some significant banding in the greyscale on the JVC LT-32P679. For example in a photo of a grey foggy sunrise you can easily make out obvious bands of light. This is an obvious interplay of the errors we saw in all three of the primary colors as greys are produced as a combination of very intense red, green and blue.

We should note, however, that this is only a problem at higher intensities of color. Across most of its color range the JVC LT-32P679 did a reasonable job of reproducing without any major jagged spikes or flat points that indicate a place where changes in intensity don't produce a change in color. Thus the JVC LT-32P679's score in this section is below average, but not the worse we've ever seen from an HDTV.

Color Gamut (5.46)
In this test we look at the range of colors that the JVC LT-32P679 is able to reproduce. Below you see a chart that indicate both the JVC LT-32P679's measured color gamut and the international standard (called the ITU Recommendation .709). Ideally an HDTV would match the international standard exactly.

You can see that the JVC LT-32P679 does not match the standard. In particular there's significant error in the greens. You should also note that the white point, indicated by a small circle in the middle of the color gamut, is also slightly off. This is likely related to the problems we had in properly calibrating the JVC LT-32P679 as we discussed in our Performance: Summary section. Since the JVC LT-32P679 did not allow us to accurately calibrate for both blacks and whites we had to choose a mid point that means both are slightly off. The practical impact is that both greens and whites will look slightly different than what was intended by the producers of video content.