What does 3CCD mean? ?

Question

It is in regards to video footage...

Answer 1

A CCD is a Charge-Coupled Device and it is the most common light sensor used for digital cameras and camcorders,  the downside is that most CCD sensors consist of a single sensor array that is responsible for all 3 of the primary colors of visible light, this gives you poor color separation.  The other sensor type available is CMOS which senses light separately but suffers from poor low light distortion.  An attempt to get the best of both worlds is to use 3 separate CCDs, one for each visible primary color.

Answer 2

3-CCD means that the camera has 3 Charge Coupled Devices or 3 Complementary Metal Oxide Semiconductors instead of a single image sensor.  This provides much more accurate and rich color.  Almost all professional camcorders use a 3-CCD design.  Many consumer video cameras also use a 3-CCD system.  Camcorders that need to see Infrared light normally use a single CCD.

The 3 CCDs are attached to a high grade prism which separates visible light into the three primary video colors schemes: Red, Green, and Blue.  Due to the properties of light, the prism is usually designed so that all the CCDs are in a general vertical column or in a general vertical arch.  The center of the column or arch is oriented towards the camera lens allowing light to properly enter the prism and separate evenly.

Each of the 3 CCDs are tuned to a different portion of the color spectrum. The top CCD handles the upper "Red" end of the spectrum, the central CCD handles the middle "Green" portion of spectrum, and the bottom CCD handles the lower "Blue" end of the spectrum.  A single CCD system has no prism and uses a single large image sensor to read the full light spectrum at once.

The image sensors only convert the visible light it sees into a digital video feed.  The camera's electronic systems make adjustments and corrections to each of the 3 video feeds and then combines them into a single RGB video.  In a single CCD system, the camcorder makes adjustments and corrections to the single video feed, but these improvements are generally not as great as in the 3-CCD system.  The video is then sent to the onboard recording media or out of the camera to an external system.

Answer 3

A "CCD" is an analog integrated circuit which functions as an image sensor. CCD stands for "Charge Coupled Device", a name which relates to how the device works. When you "expose" a CCD, every sensor (usually a photodiode) captures a charge, proportional to the intensity of the light on that individual sensor. After the exposure, the charge from one sensor site to another is "coupled", one to the next, kind of like a bucket brigade, into an analog to digital converter, and then on to the camera's digital processor.

Modern cameras are increasingly moving to CMOS (Complementary Metal-Oxide-Semiconductor) sensors, which also use photodiodes, but are based around standard digital chip production methodologies. Some CMOS sensors have an A/D converter per row of pixels, or even per pixel, and can tap into other digital processing right at the sensor, to achieve lower noise levels and a few other advantages over CCDs.

Anyway, the issue of 3CCD, or 3CMOS for that matter, is this: there is no inherent color knowledge in a photodiode -- it simply reacts to light. To get a color picture, you need to modify the light going to the sensors. For a single sensor, as used in most consumer camcorders and virtually all digital still cameras, they use a filter mask, usually following the Bayer pattern (named after its inventor, Dr. Bryce E. Bayer, who designed this while working at Kodak). This puts a red, green, or blue filter over every pixel, and uses software interpolation of nearest neighbors to estimate the missing levels (eg, if a pixel has a green filter, it knows its green value, but the R and B must be calculated from neighboring pixels). This works, but if the sensor is too small, there can be "fringing" at image edges, where the estimated colors are very different than the actual colors.

To remedy this, camcorder designers came up with a true RGB solution... rather than use one image sensor, you could use three. To split the color, put a dichroic prism system after the lens, and split the incoming light into red, green, and blue bands. So that's what a 3CCD camcorder does.

In the early days of camcorders, this made a huge difference. Consider a standard definition sensor, 720x480 pixels for NTSC. Using a single chip, you get 86,400 pixels of red, 86,400 pixels of blue, and 172,800 pixels of green with the standard Bayer pattern. Change to a 3-chip solution, and you get the full 345,600 pixels of each color... much strong and more accurate color... but more expensive.

Things have changed a bit in recent times. Most consumer camcorders use higher resolution imagers, sometimes as much as 3 to 6 Megapixels, even for a standard definition camcorder. While this is largely to support this crazy consumer demand for camcorders that can do still pictures, it also means that each video pixel can get a true R, G, and B pixel (or several), even from a single-chip. For consumer camcorders, it's also important to look at sensor size... a single chip CMOS Canon camcorder with a 1/3" sensor may actually look about as good as a Panasonic with three 1/6" sensors.

In the high definition market, it got even fuzzier. The first professional HD camcorders used three larger (1/3" or 1/4") CCDs, but none of these were full high definition sensors, but usually 1 megapixel or less (1080i/1080p is a 2Mpixel format). They got the effect of HD by offsetting one sensor from the other, so effectively, the pixels would interlace.. then they used interpolation, same as on a single chip camera. So a single chip HD camcorder can deliver similar color to a 3-chip model.

However, the 3-chip model done this way may still have an advantage. When you take a 1/3" sensor, say, and increase it from 1/3 megapixels to 2 megapixels, you have no choice but to shrink the sensor elements (those photodiodes). That makes your HD sensor less sensitive to light. You can technically add the output of multiple pixels for low-res stuff, but in HD, you are just going to be less sensitive than a similar SD cam would be. However, if you're using three lower resolution sensors at the same sensor size, you get the larger sensor sites, thus more sensitivity. So while color isn't the main issue anymore, the more expensive pro camcorders in HD will still use three sensors, but today it's mostly about light, not color.