Because these are all "low resolution" projectors - all 854x480 pixels, often referred to as 480p projectors or EDTV resolution, their pixels are inherently bigger and more visible than higher resolution, more expensive projectors.
That said, DLP projectors have significantly less visible pixels than DLP projectors. For that reason, you would want to sit further back if you are watching the Epson Home 20, than the other three. (In fact, the pixel issue, was about the number one reason the Epson didn't get our Hot Product Award.)
Immediately below, are closeups from the boathouse image that show the difference on the word Schuykill. The first is LCD - from the Epson Home 20, the second is from the IN72. The pixels are the same size, but more distinct, and therefore more noticeable, on the LCD projector.
To get a real idea as to the significance of the differences, get both of these visible on your screen at the same time and start backing away from your monitor, you'll discover that with the DLP (InFocus), the pixels really become less noticeable before the Epson.
Image Quality Slideshow
Epson Home 20
Most people don't mind sitting at a point where the pixels are "barely" visible, and mostly only in bright stationary parts of the image. For the DLP projectors that means sitting almost twice the screen width back, which for our theoretical 100" diagonal screen, would be about 14 feet back. For the same level of visibility you would be about 17 feet back with the Epson. If you like, or need to, sit closer than those distances above, you are almost certainly going to be happier with a DLP projector. (The kids probably don't care at all.)
The rainbow effect, is something that only relates to the DLP projectors, since they have a spinning color wheel. A very small percentage of the population will detect flashing rainbow colors, usually only occasionally, and some of those don't notice enough to find them detracting. Some of those, however will not be able to watch due to the rainbow effect. Remember, most home theater projectors are DLP, which tends to confirm that the rainbow affect is a problem for only a very small group.
Now that we've cleared that up, it's time to get down to the picture quality itself, excluding screen doors, rainbows, and pixels.
Projectors come in two other flavors - those with good to great color accuacy out of the box, and those that definitely can use some adjustment.
In this group of four, three do a great job out of the box. (I'm talking about for normal movie watching). Of these, the InFocus and Epson are very good. The BenQ W100 is close behind. Most people will be more than satisfied, just turning them on, popping in a DVD and enjoying the picture. The Optoma H27, however tends to favor green, not greatly, but enough to make flesh tones rather pale, and the green tends to be a little noticeable in shaded flesh tones, like the neck. My phrase is: "A little green around the gills."
The solution for the H27 is to pick up a good calibration disk, such as the AVIA disk which tends to sell around $39-$49. It's designed to be easily used by beginners, and only requires about one hour of your life to go through the tutorial, and calibrate the projector. The difference is rather significant. Once calibrated the image of the Optoma H27 is essentially second to none.
"The Holy Grail" of home theater projector performance is having great "black levels". Translated, that means that the projectors get very close to being able to produce black. (Only CRT projectors reallly can). The better the black level, the darker, the darkest grays the projector can put on the screen, so everything that is supposed to be black, ends up that level of gray. If a projector doesn't get very close to doing black, then much of the very dark parts (shadow details) get lost.
Generally, high contrast ratios, is an indication of black level performance, but that has changed in the last year or two, as techniques such as irises that dynamically adjust from frame to frame, and lamps that adjust brightness from frame to frame are used in some projectors to lower black levels when they can. The end result, high contrast ratios, can be misleading.
In the search for the blackest black one of the four projectors stands out, and that is the InFocus IN72, it's blacks are very impressive for such a low cost projector. Not quite as good, is the Optoma, the difference is definitely visible, but the H27's performance is still very good in this regard. Trailing the H27, next comes the BenQ, with decent but not impressive blacks and shadow details, and lastly, the LCD powered Epson. Inherently LCD projectors have trailed DLP projectors in this regard, which is why they are more likely to have "AI" circuitry controlling irises and lamps. The Home 20, however claims a low 1000:1 contrast ratio, and does not rival the others.
Let's look at some images:
Here are the four projectors tackling the image of Arwen from Lord of the Rings. All images were shot with the same digital camera, but at different times. Slight differences in brightness are normal in the attempt to get the best exposure, and do not indicate which projectors are brighter than others.