With the ASUS S1 Pocket Projector, ASUS has managed to shoehorn a surprisingly capable projector into a nearly rectangular block that's small enough to fit on your palm. It even looks good, with a silver metal case, rounded corners, and a high quality fit and finish. Like most projectors this size, it's built around a DLP chip and an LED light source. Also like most, it's meant for both casual home use and for business presentations on the go. The native 854x480 resolution, with its 16:9 aspect ratio, seems targeted more for home than business, but the 200-lumen brightness rating, measured at 150 lumens, makes it bright enough to be useful in either role.
Note that the only input is MHL-enabled HDMI. That makes it easy to use with an MHL-capable phone or tablet, but also means you may not be able to connect it to your laptop. Assuming you can connect it, however, it can be a highly useful traveling companion, and nearly an impulse buy, at $319.99.
The Viewing Experience
Like most projectors in its size and weight class, the S1 is built around a DLP chip that's designed to maximize brightness, but also adds apparent scaling artifacts. The artifacts are most obvious as added patterns in areas filled with repeating patterns of dots or fine lines. They can also give images a soft focus look.
You'll see similar artifacts with any DLP or LCD projector if you use an input signal that doesn't match the projector's native resolution. With the S1, however, they also show up at the native 854x480. Fortunately, this isn't necessarily a problem. If you don't use patterned fills in graphics, you may never see the artifacts, and even if you see them, you may not mind them.
The S1 has an advantage as well, compared with higher resolution models with the same issue. If 854x480 is the appropriate resolution for your needs, you probably won't be showing images with a level of detail that will be noticeably affected by a slightly soft focus. And given the SD resolution, you're not likely to notice any effect in video or photos either.
Rainbow artifacts (flashes of red, green, and blue) are another potential issue for any DLP projector. With the S1, I saw them infrequently enough with data images that it's unlikely anyone will find them bothersome. With video, I saw them often enough that anyone who sees them easily will notice them, but infrequently enough that few should find them annoying.
Also demanding mention is that the S1's color brightness matched its white brightness in my tests. That's notable because many DLP projectors, including models that use LEDs, have significant differences between the two, which can affect both color quality and the brightness of color images. Having the same value for both means you don't have to worry about that possibility.
Data image quality. In most other ways data image quality was impressive for a projector in S1's size and brightness range. Color balance was excellent, with definitively neutral grays at various levels from black to white in all predefined image modes. Color quality was just as good, with vibrant, eye-catching color in all modes. More important for data images, the S1 handled detail well enough for any images you're likely to use an 854x480 projector for, including PowerPoint slides. White text on black, for example, was crisp and readable at 9.0 points, and black text on white was easily readable at 7.5 points, despite a minor soft focus effect.
Video quality. Although the S1's video quality is limited by its native SD resolution, its (nearly) 16:9 aspect ratio at least lets it take full advantage of the resolution it has with widescreen video. Colors are within an acceptable range, as long as you're not too much of a perfectionist. However, the predefined Theater mode has obviously better color than the brightest mode, which tends to give skin tones a green tint. That basically leaves you a choice between noticeably better color and a larger usable image. Colors also tend to be a little flat, as you would expect from a low contrast ratio.
On the plus side, the projector did a good job with shadow detail, even with clips that many data projectors have problems with, and it showed only a hint of posterization in scenes that tend to cause that problem. As long as you don't see rainbow artifacts easily, or don't mind seeing them occasionally, the video is more than watchable for long sessions.