Digital cameras: yesterday, today and tomorrow
Jul 1, 1998 12:00 PM
Digital camera technology opens up new worlds of visual interaction, but buyer beware.
Are you old enough to remember the hype surrounding digital effects when they were first introduced in the movies? I am! I specifically remember wondering just what "digital effects" meant.
The same thing has been happening to the video camera. Over the past 10 years, it has gone from the basic tube technology that started the digital motor running, to the charged coupled device (CCD), which slammed it into third gear. Digital technology is nothing new; it is actually more than 30 years old. The effect it is having on the development and application of the video camera, however, is yet in its infancy.
Since the move to CCD, digital interfacing has been taken to new heights, opening up new worlds of visual interaction.
First came CCD The first, most obvious effect of the digital revolution on cameras was when the tube walked out the door, and the CCD ran in. Although the original CCD cameras were a great innovation, they left a lot to be desired, including two of the singularly important features of security video cameras - resolution and sensitivity. Also, because the rules and wording of the CCTV game had changed, many people spent thousands of dollars on the new cameras without understanding the language that described them. Consequently, many of these pioneering users felt cheated.
* Buyer beware of new technology: If you don't understand the language used or the general differences between what you have and what you are getting, learn - early, fast, and before you spend the bucks.
One of the original digital options was the ability to control the "electronic" shutter speed of the CCD. Shutter speed normally refers to how fast a mechanical shutter will open and close, exposing standard film to X amount of light. In video cameras, however, electronic shutter speed refers to the amount of time that we leave the CCD turned on. It is a form of electronic light control, and it was the first step toward developing a camera that required no auto-iris under adverse lighting conditions. This control started out as a manual adjustment and was adapted to automatic very quickly.
Then came digital zoom However, as the world turned, electronic shuttering was replaced with supplemental, after-the-fact electronic signal enhancement techniques. Digital zoom - another attempt to replace the lens - came down the video enhancement path right at the beginning.
Digital zoom takes an existing image and explodes a portion of it. Imagine laying an invisible grid over a 12x9-inch image, creating grid squares of 1x1 inches. Pick any area within the grid that is eight squares wide and three squares tall. Explode this grid area, and fill the screen. You have now digitally zoomed in on the image.
The downside of digital zoom, however, was an extreme loss of resolution. It is one thing to come closer to an image; it is another to blow up a bunch of squares. What good was making an image larger if you couldn't tell what the heck it was after X amount of expansion? Early digital zoom efforts were clumsy and ineffective for the security industry.
The good news is that after years of experimentation and a whole lot of creative technology, digital zoom enhancements are now available with incredible accuracy and resolution. We still work off of the same grid theory, but now built-in computers average and smooth the gaps between grid squares, creating very sharp closeups of far-away images without an expensive lens.
n Buyer beware: Test all zoom claims personally before investing to ensure you are not purchasing the older, clumsy technology. As for worries about whether or not such images hold up in a court room (because they are digitally enhanced), have no fear. Since the enhancements are automatic and take place at the image's point of origin, there is no room for personal or secondary alterations. Therefore, the image is considered original and unmodified.
Video motion detection Video motion detection is another great option that suddenly became available, built into the camera. No longer did we need a black box interface to determine whether there was motion within an image, creating an alarm. Now we had cameras that could be pointed and programmed to detect motion within their scope of view. Motion detection could be activated or deactivated at the camera, at the controller (on an individual basis), or on a timer, depending on the camera and interactive controlling system. This greatly improved the integration of video systems with security. Not only do such cameras detect motion, but some also highlight the area that is moving with an overlaid white square or rectangle. This way, the person viewing the alarm-causing image can see the point of alarm quickly and efficiently.
Video motion detection works on the basis of contrast change. Again, lay an imaginary grid over your image. All you need to do is look for a change in the brightness of any square and you have contrast change. The sensitivity of motion detection depends on the total number of grid squares that must change and how much difference between the original brightness of the grid square is detected before an alarm is activated.
n Buyer beware: These cameras are best used in fixed, indoor environments. Even in the newer, more sophisticated cameras, built-in video motion detection is still very simple. This form of video motion detection is not desirable for use outside or in areas where you can have drastic and sudden light changes. There are too many potential false alarms outside. If you are looking for sophisticated motion detection, you still need to use a separate digital video motion detection unit that interfaces with your camera system.
Menu-driven programmability Another digital enhancement to cameras that came onto the scene early was menu-driven programmability. With the push of a button, a whole menu of programmable options would show up on your screen, such as: indoor, outdoor, flourescent lighting setup for color cameras; the ability to turn on the automatic light control circuit to enhance dark shadows; and auto-iris override, giving the operator the ability to open or close the iris manually from the camera or the controller.
* Buyer beware: In many cases, some of the options available for manual override or programming are not something you want your operators to be able to do during their shift. There are still some things better left alone and for automated decisions.
Seeing into light and dark simultaneously Seeing into light and dark simultaneously was another task that was left for the human eye alone. Cameras could not handle this function until recently, primarily due to the art of light control being left to the iris on the lens. If the iris closed down to compensate for a bright area, the shadows in the scene would become deeper. Vice versa for the lens opening for a darker area, in which case the bright spots would become unbearable and washed out. We had been up against the proverbial wall for 30 years when it came to seeing someone standing in front of a glass door or window. It just couldn't be done until ... digital cameras.
Watec was the first to develop a camera with near-human-eye-quality sight into bright and dark simultaneously. It did so by concentrating on the video signal after it was created by the CCD. Toning down the bright areas and amplifying the dark points of the scene, Watec developed the "electronic iris." The problem? This technology is only available on a few select cameras.
Panasonic recently took the lead by developing a completely different approach to this age-old problem. By using electronic shuttering techniques, they literally take two pictures simultaneously. One image is taken at 1/60 of a second to see into the dark areas of a scene. The other image is taken at 1/10,000 of a second to see into the bright areas of a scene.
The two images are then digitally combined, and the result is a very clear, sharp image of human eye equivalence. They call their design "super dynamic" - a fitting enough name.
* Buyer beware: Since there are no standards for terminology in the CCTV industry, carefully investigate exactly what you are buying. Every vendor has its own labels for its technology. What one vendor calls electronic iris may be the same thing another calls electronic shuttering. Consequently, you must know your manufacturer and the details behind their terminology. In the end, a complete test, demonstration - or even a shootout - between different manufacturers is advisable prior to big-bucks investment. The rule of thumb is: If it provides you with the image you need under the circumstances you have, use it.
Today and tomorrow Just how far are we from the perfect, completely digital camera that will do it all? We are on the road, but we have a long way to go.
For today's small systems, the sophistication of digitally enhanced cameras is such that they offer many functions and features, which, in the past, were either restricted to big controlling interfaces or were too cost-prohibitive. Today's large systems now offer operators more control over individual and group functions and features from a single point of operation.
As for the future, I don't think it will be too much longer before we see a completely digital camera that requires no lens, no setup, nothing. Just mount it to a wall, point, and walk away. Want it to pan across an area? Set the digital screen for the exact area that you want panned and there you go. Want to zoom in or out? Push a button and digitally take care of the job. Need to see into a shadow? Push a button and suddenly the shadow is gone, but ... * buyer beware: Not all digital technology is fully proven before it is thrown onto the market. Don't feel foolish for requesting an in-field demonstration. Remember to verify warranty conditions, and ask about serviceability. It will not do you much good to purchase 100 wonder cameras only to find that if one fails, it will have to go to Japan to be repaired. It is equally bad if the unit you buy today will be discontinued a month or two after it is delivered.
Choose your digital enhancements and applications carefully, and you will enjoy the results for years to come.