Optoma PK320 Pico Projector Review
Great peak brightness is offset by an inaccurate color gamut.
Towards the dark end of the brightness spectrum, the color temperature strays towards the cooler side. This means that dark gray and black values may have a blueish tint to them, but at this low luminance, you should not see anything, let alone some minor tinting. This cooling is very slight and should not be considered a detriment.
These color curves show how well a projector can reproduce the three primary colors along the brightness spectrum from dark to light. The curves you see in the chart below would be ideal if not for the green values.
If you look at the red and blue lines, you see two smooth curves that reach from 0 to 100% luminance, in even transitions. The green line is quite different, starting out way too bright and finishing at not quite bright enough. Furthermore, throughout the spectrum, there is up and down motion to the graph, showing an inability to reproduce brightness values of green. These bumps show a shift from too bright to too dim, never reproducing green at the correct brightness for the given input signal. Oh well, at least the red and blues will look strong.
Where's all the saturation!? Previously, we saw problems only with the green values in terms of luminance value reproduction, now we see that the green colors are the only accurate ones when matched up to the Rec. 709, the international standard for HD colors. The red and blue colors are drastically undersaturated.
We even retested the colors using the expanded color range, and found that this adjustment did not help the situation, rather the gamut errors were slightly greater than using the standard color range. The biggest difference was an inconsistent color temperature, so we recommend leaving the color range on standard.
Combining the knowledge we have, the green colors are accurate, but transition from dark to light poorly. The red and blue values are not quite red and blue, but have great brightness reproduction across the spectrum. The mixture of these benefits and deficits makes for an odd set of colors, but a picture that is actually watchable in our regard. You may notice that something is not quite right, but you may also be lulled into watching a strong picture by how good the colors look in relation to one another on screen.
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