Those of you that use chroma keys in your production will know that getting a satisfactory chroma key can be almost a black art. An operator can spend a lot of time tweaking setups and the result is often still a compromise. After all this, your talent chooses a different wardrobe and those settings that were carefully labored over now do not work so well.
Even when everything seems just perfect, the cameras are faithfully calibrated, the lighting is great, and the talent is wearing just the right outfit, they key result may still be disappointing – and there are some fundamental technical reasons for this.
When generating a key from Chroma information – you are working with only half of the resolution that is generated within a 3 chip camera. This is due to the 4:2:2 encoding process used for SMPTE standard SDI Video transports. Of course 4:2:2 encoded video works perfectly well for most other applications, but with only half of the color resolution available, you can only resolve half of the detail in Chroma Key edges. Ideally for a great chroma key you need a 4:4:4 signal, but that would require more signal bandwidth for the same frame rate and be incompatible with the rest of the devices in typical production systems.
Then there is noise. While most broadcast cameras have very acceptable signal to noise ratios, noise is measured in the Luma channel, but chroma levels are always lower than Luma values and so are inherently noisier. That noise ends up in the chroma key edges unless it is filtered out – which lowers the edge resolution even further.
These issues have been considered at Ross for some time, particularly now that more virtual sets are being deployed than ever before. Naturally as a leader in virtual set technology, Ross has been driven to find a way to produce higher quality chroma keys.
Now the solution is here. Ross has developed a unique new signal format that must be output directly from the camera. This type of format is not available from current cameras, so Ross has developed its own. The new ACID cameras from Ross have two outputs – a standard SMPTE HD-SDI output –and a Ross designed UltrachromeHR 0:4:4 full bandwidth color output.
In order to create keys from this new signal, obviously a new chroma keyer design is needed as well – so Ross has built that too.
The new Carbonite UltrachromeHR chroma keyer, which is a stand alone multi-channel chroma keying system based on the Carbonite Black processing engine, can take both camera signals and internally combine them to generate full bandwidth key edges. The chroma keyer outputs standard HD-SDI 4:2:2 signals that are beautifully composited with your virtual environment.
The Carbonite UltrachromeHR chroma key system will also produce amazing results from standard 4:2:2 camera inputs, and is probably the best chroma key ever designed. It is also equipped with features and ease of use that you will not find in any other product, but of course the combined package with Ross ACID cameras is unbeatable in the virtual environment.