The applet first loads an imge of Stanford Medical Center at level 3 of the image pyramid. (Level 0 is the original high resolution image 3500x2400). You can select image of other resolutions by using the choice button. For buttons labeled "Left", "Right", "Up", "Down" are provided for navigating around the image. Pushing the "Up" button will move the image upward to reveal the portion at the bottom. Move the mouse pointer to a specific position in the image you are interested in, and click the mouse button will zoom in around the click point. A higher resolution image will be loaded, and the mouse click point is displayed at the center of the applet window. Click the mouse button with the "shift" key down does zoom out.
As you load a new image resolution, you will notice that the new image is displayed progressively tile by tile. This reveals the fact that the applet is requesting necessary portions of the image from the server tile by tile. Only the tiles that are exposed in the applet window are requested. Tiles that are clipped by the window are not requested and transfered, thereby saving significant amount of time.
When you pan around in the image, you will notice that areas you have visited are redrawn very fast. This is because the tiles are cached inside the applet and doesn't need to be transfered from the server again.
You will see an image pyramid by selecting a higher resolution followed by successively selecting lower resolutions. For example, use the choice button to select level 1 image first, then select level 2, level 3, level 4, a nice image pyramid is displayed.
Advantage of FlashPix
This applet demonstrate the power of FlashPix. You can load a low resolution image first, get a general idea of the image, then zoom in to the area you are interested in to get more details from a higher resolution image. Only limited amount of tiles are transfered for the higher resolution image. You can click on the redraw button to redraw the image, and then you can open the Java console from a Web browser and see what percentage of tiles are transmitted for each resolution. Typically, for the highest resolution, less than 10% is needed.
(Caveat: This Java Applet uses JDK 1.1. The most reliable web browser I've tested is Netscape 4.5 on Windows. On unix workstation, please use the following command to view the applet:
appletviewer http://www-ise.stanford.edu/class/psych221/99/sliang1/FlashPix.html
)