Video Display & Camera Imaging

Video Displays

There are a number of choices available for viewing your microscope image in a large format size on a video screen. Here are three:

1. Good--Use of a standard TV/VCR combination set. These units have direct video inputs so you can plug the composite video output of the camera directly to the TV. Because these are generally consumer units, we do not supply them. They are an economical very low cost option
   
   
2. Better--Since our primary camera units have high resolution s-video output capability, matching this with a professional level monitor with s-video input is a nice choice. On pro monitors you also have the ability to switch between multiple inputs so you can easily switch from microscope view to video printer or VCR view by pushing a button on the front of the monitor. The Panasonic Pro 13" monitor shown on top at the right is this type of unit.
   
   
3. Best--High resolution laboratory monitor like the Sony unit shown here. This offers multiple inputs as well as being s-video capable. What sets the Sony Pro Lab monitor apart from anything else is its very high resolution. View the screen up close and it is near impossible to see the phosphor dots that are readily apparent on other video screens. This is a choice without compromise.
   

Understanding Video Resolution

The Video Signal

Standard video cameras can have three types of outputs available. Composite video, s-video (also called Y/C), and RGB. Composite video is the same type of video that goes into or comes out of the back of any ordinary video tape player. It usually does this through a phono plug (also called RCA jack/plug). All of the video signal is sent down two wires--the signal wire and ground.

A better choice is s-video (Y/C). Here the video signal is broken down to go over 4 wires, 2 signal and 2 ground. It offers a higher quality signal in general and a bit more resolution.

The third choice is RGB. The video signal is broken down into its composite red, blue and green components. This offers the highest quality.

When testing the image difference for live blood microscopy and comparing between composite and s-video using a Sony lab monitor, the s-video is visibly better. Between s-video and RGB, the two are indistinguishable. Therefore, RGB offers no advantage so no extra cost needs to be spent for RGB. The exception is when moving to a three chip video camera where RGB plays a role. These are on the very high end microscopy systems averaging $12,000 or more in price.

Monitor Phosphor Dot Size

Take a look at any standard TV set. As you get close to it you will be able to see the phosphor dots (or squares on some units) clearly visible. With high resolution lab monitors, the phosphors are squished together more and they are difficult to detect, thereby rendering a cleaner more refined image.

Video Cameras

Standard video cameras have CCD (charged coupled device) chips where images get focused from a lens and are then translated electronically to a TV picture. There are new low cost options using CMOS chips which up to this point in time, still do not have the quality resolution necessary for biological medical imaging. And then there are straight digital cameras that can go directly to a computer monitor arrangement. At this stage of development, digital cameras only work for still imaging. The frame rate (how many picture frames the camera takes each second to make a smooth moving live picture) is in the range of 15 frames per second.  We would ideally like 30 frames per second for live blood imaging. Anything less leaves a jerky picture which is not acceptable for live blood biological work.

Analog CCD chip cameras are the video standard currently in use for live biological imaging. These can be either one chip camera or 3 chip cameras. Where a single chip camera can generate up to 500 lines of vertical resolution, a 3 chip camera can generate up to 850 lines. Internally, the best cameras will use digital signal processing. You should note that not all cameras offer the same image quality, even if they have the same specifications. You have to look at the image quality with the intended application to discern what works well and what does not.

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