The screen quality of the PL 720

Of tremendous importance of a PDA is its screen quality.

Screen quality is not only dependent on the resolution of the screen; much more that of of the basic "cast" of it (is it yellowish? bluish? purplish?) and whether the colors are vivid enough.

Unfortunately, most PDA screens on the market are pretty lousy. The two main reasons for this are as follows:

  • Pocket PC's with QVGA (Quarter VGA) generally suffer from a strong color cast (slight purple on the iPAQ 36xx/37xx series, very strong purple cast on the 38xx and yellow from most of the newer, lower-end iPAQ's, particularly from at angles, mostly from below with the iPAQ 1930/1940 and the 4150).
  • Furthermore, their "contrast" is pretty lowish. "Contrast" means, in this case, that they just can't render some colors as well and vividly as they should be. Most screens have tremendous problems with "warm" colors (mostly with red). Furthermore, even the best screens that are otherwise excellent at rendering red may fail at rendering some other colors (e.g., the Casio and green, as will be clearly seen).

    PDA's are excellent digital photo wallets. That is, they WOULD be excellent if they had screens with great contrast and vivid colors. Too bad not even the "latest and greatest" PDA's offer this functionality. Sure, you can show your pictures on even an iPAQ 38xx (maybe the worst TFT PPC of all time), but nobody will really enjoy them because of the sub-par contrast and very strong purple cast.

    Therefore, in my test, I tried to find photos that have strong red/white/green components. Furthermore, I've added some of my color bars.

    I've put to test all my color Pocket PC's (and my palmOne Zire 71, which has an extremely good, vivid screen). Before you ask: yeah, I own all of them and also the PsPC's in the background. Of course, I didn't want to enter old, B&W PsPC's in the test ;)

    These are as follows:

  • iPAQ 3660: not much to say here. An old, reflective model. No wonder its screen quality is pretty bad. It's only at outdoor visibility that it excels; however, the latest VGA models seem to have pretty good outdoor visibility too. 1-2-year old transflective models don't (will also publish some comparative pics on this subject too), and the Casio, with its transmissive screen, certainly not (ever tried to make out the contents of the screen of a Casio or a Jornada 680 in direct sunlight?).
  • iPAQ 2210: a tolerably good machine with a sub-par screen. It's infamous for its "washed out" colors. It's not just an urban legend: as my test photos also show it, it indeed has very bad contrast.
  • Casio Cassiopeia E-125: a PPC device famous for its excellent, vivid, bright screen. It has a little yellow cast and doesn't really excel at greens, but at least the reds are extremely vivid, unlike on most other PPC's.
  • Fujitsu-Siemens Pocket Loox 720: it's very hard to be NOT to be astonished at this screen. By far the best PDA screen I've ever seen; orders of magnitude better than ANY reflective/STN screen. Even better than that of the Casio Cassiopeia E-125 and the Zire 71.

    Eagerly waiting the test pics? Well, here they are. I've used a Nikon Coolpix 5700 on a semi-professional Manfrotto tripod to take the pictures at 5 Mpixel and Fine JPEG. EXIF infos are present in the test JPEG's.

    Note that I've used auto color balance. This is why, on some pictures, only the E-125 seems to have the right color balance. Don't let this mislead you: it's clearly the E-125's yellowish basic cast and warm colors that "fooled" the camera's color balance to switch to colder colors. In my next article, I'll use non-auto color balance to achieve comparable results.

    The machines, from left to right: iPAQ 3660 (same screen as in all 36xx/37xx iPAQ's), iPAQ 2210, Fujitsu-Siemens Pocket Loox 720, Casio E-125 and palmOne Zire 71.


    Let's start with the green color. It's not as important as, say, red, when speaking of differences between PDA screens, but the rendering capability of the green color of different PDA's still needs to be tested.

    Let's see how the grass' green is rendered by the PDA's. The original picture was the following (this file was given straight to the PDA's - you can also do the same by saving the picture and loading it to the PPC. Where there was no built-in picture viewer (PL720's Album, 2210's WM2003 Pictures, Z|71's Photos), I used LimeLink's CEpicture - The original photo was taken on the river Matkusjoki, near Sonkajärvi, Finland, July 2004:

    And the results (click on the image for the original, 5 Mpixel picture!):

    As can be clearly seen, the Casio doesn't really excel at reproducing green colors; even the otherwise quite bad 2210 seems to be better in this respect.

    Warm colors

    This is maybe the best test picture of all because of its really warm colors. Original (a Finnish friend's children):

    PL720's colors are by far the best. Casio's colors aren't bad either, but they're clearly much more "washed out" than those of the PL720. The two iPAQ's are clearly the worst.

    Original (taken at the Summer Services of SRK, Finland, July 2004):

    Pay special attention to the young lady's red coat!

    Original (also taken at the Summer Services of SRK, Finland, July 2004; also pay attention to the red coat!):

    Original: an ostrich egg from a Finnish ostrich farm. Especially strong warm colors and blue. The closest to the original is definitely the PL720; the E-125, though has a good rendering of the warm colors, is far too warm and is, therefore, not very natural (check out the yellowish cast on the hand and compare it to PL720's rendering of the same colors!):

    Gradient bars

    These bars are great at finding out if a particular machine is weak at, say, rendering a particular color. When creating the bars in Photoshop, I paid special attention to the strength of all colors: I've used the strongest possible color value at the bar's end (e.g., 255 in a 8-bit-color). It' with this test picture that I've also taken some pictures from angles. It's not as cool as taking a good-quality, hi-res 25 fps video from angles, slowly moving the camera from the center to left-right / up-down to simulate different viewing angles, but my video cam is just being repaired. Will post some videos too when I get it back.

    Incidentally, the PL720's visibility range is pretty good. Two people can use it as a digital photo wallet at the same time with little (but certainly visible!) quality degradation, comparable to the 2210 or the Zire71. The E-125's quality degradation, when two or even more are staring at it from different angles, is much larger.


    From the usual, straight position:

    From the left (to see whether a particular screen has natural colors, or, at least, visible from the given angle):

    From the right: