Video

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Feed back and additional contributions on this subject are avaialable on a video page

Link to Vision 1, a dealer in video capture cards, video cameras and digital cameras.
There are lots of options for video, but many fewer for getting from the video to a computer image. Many people actually find it easier to shoot slides then use a slide scanner to get the images onto their computer, or shoot prints and flatbed scan the prints. The other option is to get a "Photo-CD" from Kodak when your transparencies are processed. This is a CD-ROM containing scans of each of your slides, ready to view on your computer or copy into figures. Good slide scanners are also pretty cheap these days. The Nikon Coolscan is about $1,400 and scans at up to 2700 dpi. We have a Nikon unit, which works on Mac, PC and NeXT hardware. The Polaroid scanner is also meant to be very good. It is only about $1,500 and is many times faster than the Nikon. The other advantage of scanners is that some can accept histological slides and scan them directly, no more need to photograph sections then scan the photos.

For cheaper options, read on. For a description of more expensive high resolution video system, see the information provided by Robert Davis. For a moderately priced system see the information provided by Vision1!

Cameras

As far as video cameras go the quality of cheap cameras has improved to the point where it is hard to justify an expensive light integrating camera for most purposes. There are many options on the type of video signal camera can produce. The lowest resolution is the American NTSC standard (about 350 lines) followed by the more universal PAL standard. Next best is Y/C, yc, S-video or still video, all the same, the high resolution video used by laser discs and super-VHS (about 450 lines). This is the cheapest high resolution version video and probably the most convenient (remember you must have a monitor and/or computer input that matches your camera output!). Next best is RGB followed by digital RGB. Actual line resolution is probably not much better, but better color resolution and balance. The more chips, the better.

On our scope we have an Optronics LX 450A. This is an expensive ($4,500) unit, but has very good image quality, low light sensitivity (0.5 lux), and multiple outputs; RGB, digital RGB, y/c and NTSC. It also has a computer keyboard that lets you alter exposure, enter dates and times, and switch between exposure modes like center weighted or full screen. We also have some simple cheap cameras for $960 that do almost as good a job without all the extras. We buy these from Motion Analysis, USA phone 800 935 3440. It is a model CV730 YC video camera cat # CV730YC, with a 1-2A regulated VDC power supply cat#PD-12CV. This is a high resolution low light camera good for genera purpose video.

Monitors; get a cheap one. You can spend $1000 for a small 1000 line resolution job that is not really any better (at the resolution your camera can produce) than a cheap S-video model. I suggest a Panasonic 20", about $395 from Motion Analysis. If you have an RGB camera, you will of course need an RGB monitor. The Sony units are excellent, but expensive.

Video storage

. You can store very high resolution video images on a specialized DAT drive made by Mitsubishi, and sold by many microscope manufacturers, for example Leica. It is a DX-2000U. You just press a button and about 5 seconds later have a very high resolution stored image. The machine is expensive, about $3,000, but storage is free. Over 1,000 images fit on a $10 DAT tape. The other storage option is a recordable CD ($1,500) but this will require a computer digitizer. The CD burner also works best if you store up a whole disks worth of information on a hard drive and copy it over at once, not always convenient. We store our data on the DAT drive, and shoot dozens, sometimes hundreds, of images for each experiment, then download the ones we want for slides or figures to the computer only as we need them. The recorder takes 7 seconds to read or write a file, and can also be used for time lapse as long as the delay between shots is at least 7 seconds. On the computer we use hard drives for image storage for speed, we have over 6 gigabytes of drive space hooked up.

Computers and digitization.

Resolution and color depth. "Screen resolution" boards that grab at 640 x 480 pixels are OK. The image will look great on your screen, and be good enough to output to slide makers, or to paste up into a composite figure for publication. All the images on the Xenopus page that were captured directly were done at this resolution. It is of course better to have more resolution, and boards that grab at 1024 x 780 or higher are available. This is much better. You can blow these images up on the computer screen a few times before you begin to see pixels, and they are much better quality. These boards will cost more but are worth it. They are available for the Mac and for PC based computers. For even higher resolution you can move to a digital camera (1500 x 1200 pixels, or even up to 3,000 x 2,000 pixels). Some cheap ones are coming out, we plan to test a $1,000 model in the next few weeks (pixera 1 million pixels)

In terms of color we have a 32-bit board (best) but 24-bit versions would also be fine. We also use ours at the 16-bit setting sometimes to save computer space and the images look very good, at screen resolution.

First let me describe what we do to capture images, then move on to the little I know about Mac equivalents, and finally digital cameras. It is important to buy a good digitizer, not a "toy" Mac digitizer made for generating QuickTime movies, the resolution will not be sufficient. It doesn't matter how many frames per second it can grab, the only important thing is resolution in pixels, and color depth. If you want to do time-lapse, you do not need 30 fps and other products would be more appropriate.

We use a NeXTDimension computer system. This unit has built in video capabilities but they are quite old and better systems are now available. You simply plug the yc video cable from the camera into the yc jack in the back of the computer with the card and you are set. You must then run a program to see the video image, and when you start it up a live microscope image will appear. Anytime you want to stop the action and take a photo you simply press the freeze button, then "Grab" the screen. This saves the video screen in 32 bit color at a resoltuion of 640 x 480 pixels. NeXT is a software system more than a specific computer. You will see a modernized hybrid version of this beautiful system with the new Mac Rhapsody operating system- it will be great!.

I am not a Mac person, so cannot comment on the usefulness of inbuilt Mac video in the Mac AV series, it is probably not good enough. Robert Davis has some interesting input on this subject.. I did look into 3rd party boards at one time, and some were available with 1024 x 1024 resolution. They were about $3,000 two years ago and are probably much cheaper now. You will find that boards often come with different RAM options, the video board carries its own RAM. Our NeXT video board carries 8 MB of DRAM, and I would recommend at least 4 MB. You will need the RAM on Mac boards for high resoltuion capture. Once again products like Video Spigot and Video Vision at 640 x 480 resolution are probably fine, but get a higher resolution board if you can afford one.

The more resolution, and the greater colour depth, the bigger the file. A 32-bit 640 x 480 pixel file takes up about 0.8 MB with LZW compression, 1.544 MB uncompressed. LZW is a good compression system that results in no degradation of image quality. JPEG compresses more, but also looses detail at high compression ratios.

If you have additional information on video capture/storage, especially Mac or PC please forward it. See comments by Robert Davis and Matt Cockerill on the video feedback and comments page. For a description of more expensive high resolution video system, see the information provided by Robert Davis.

Digital Cameras

Probably the way of the future bit not really ready yet. Of the options available today (that I know of) only the Kodak DCS is appropriate for use on a microscope (for under $40,000). It looks, and is, just like a Nikon camera body that you mount on your camera port. It can shoot 50 (?) color images and store them on an internal hard drive. You then down load the images directly to your computer via a SCSI cable. They are very high resolution (1,524x1012 pixels) and full color. Cost, $10,000. The only disadvantage over video is that you don't "see" the image until it is downloaded and opened on the computer, so have no instant feedback on the quality of the image as you do with video. Higher end digital cameras have both digital and video preview outputs. Each Kodak digital image is 4.5 MB in size.

The Fujix version the DS515 also sounds good, but has lower resolution, less color depth, and is designed for PC interface only. Cost, $13,000. The Leaf Scanner cameras are probably inappropriate for microscope use as 1) they are heavy and 2) they are multi-pass scanners (each RGB color scanned in a different pass), so each scan takes some time resulting in an effective long "shutter" time. I have not actually tried one but doubt very strongly it would be anything but blurred.

Still video cameras would be fine, but at the moment only fixed lense versions are available, and can not be mounted on a microscope.
For lots of info on digital cameras see the September issue of MacWorld. I just visited a lab who use a Roche Imaging Systems digital system, stunning resolution and image quality. Up to 3,000 x 2,000 pixels in full color. The camera also has a video signal, so you can use video to preview, focus etc, then shoot the final high resolution image, which at full resolution will take up 40 MB. Price, $45,000 (includes) a high power PC to run the camera.

Peter

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