Message-Id: <mailto:199409091848.NAA10319@library.wustl.edu> Date: Fri, 9 Sep 1994 11:43:38 -0400 From: "mailto:Walter_Gilbert@UMAIL.UMD.EDU--Maryland" <WALT@UMDD.bitnet> Subject: Re: slide imaging technology To: Multiple recipients of list IMAGELIB <mailto:IMAGELIB@ARIZVM1.BITNET>
In response to Manning's request for info about Kodak image servers.I am concerned about the effectiveness of making images available directly from Photo-CD discs because of speed issues. We have become acclimated to fast response from our computers and networks. I have not used the Kodak disc serving system, but I imagine with works something like this. * request for image received by server (Unix-based, I think) * server goes to the jukebox, selects the CD, loads it, and spins it up (this has to take several seconds) * if the server is very smart, it doesn't have to read the directory from the CD, hopefully it knows which image number it is after. * the image of the desired size is read from CD. If it's the 512x768 base image in a good double-speed reader, this takes about 5 seconds. * unless you have super video cards and monitors on your networked computers, that is, that can display the 24-bit image directly, the image has to be dithered down to 8-bit color (Kodak does a great job of this). On a spiffy server, this shouldn't take too long, say a second. * finally, the image has to be delivered to the networked computer. On my campus this takes about 5 seconds (for an uncompressed .BMT image of about 390KB). If I add up the preceding, we're talking about 15 seconds. Other things could make it worse. If you need to use a compressed format like .TIF or .GIF the receiving computer must decompress it. Unless you have a lot of fast computers on your network, you can add many, many more seconds to the process.
Another "problem" with using the images directly from the Photo-CD is cropping. Almost no images exactly fill the frame, so to make nice images look nice, I like to crop them.
What we do is to read the images from the Photo-CDs onto a Novell server in 8-bit .BMP format. From here we can bring up an image on hundreds of computers on campus in 4 to 5 seconds (cropping makes images smaller and many load faster than 5 seconds). With a 1GB drive now at about $350, it's getting "real cheap" to load lots of data onto servers. Walt
Walter Gilbert, Asst. Dir. mailto:Walter_Gilbert@umail.umd.edu Computer Science Center Manager: Teaching Technologies University of Maryland at College Park 20742-2411 (301)405-6727