With Great Ceremony, CARERI and CAST form Image/Video Lab in China

CARERI is the Chinese Aeronautical Radio Electronics Research Institute, a government-sponsored group focused on the research and development of integrated avionics system and its core equipment. CAST's Newton Abdalla recently visited their headquarters in Shanghai with our local partners S2C to sign a joint image and video IP agreement between CAST and CARERI.

The prestigious agreement creates the CAST IP Joint Lab, a physical lab space within the CARERI facility to be used for research and development on IP for video and image compression and transmission. To get the lab work going, CARERI licensed our new, hardware/software, ready-to-run, H.264 Reference Design System.

Part of the licensing agreement was that CAST participate in a formal signing ceremony in China. Newton made his way to CARERI headquarters with S2C's Lawrence Liang. Before arriving, Lawrence enhanced the signing gifts Newton brought—some very nice custom pens—with beautiful leather notebooks. The partnership and participating in the signing ceremony were already very important to us; this gift upgrade gave us a better sense of how important the symbols of the partnership are in doing business in China.

That ceremony with CARERI's president involved speeches on both sides in a room filled with flowers and Chinese and American flags, everybody wearing matching floral lapel sprays, and the unveiling of a large marble plaque commemorating the CARERI-CAST Joint IP Lab. Newton made out on the gift exchange, receiving for CAST an impressive traditional Chinese decoration.

We were honored to be part of the signing ceremony, but are even more excited about this great partnership and the work CARERI's engineers expect to do with our H.264 video encoder system.

If you're going to DAC, stop by our booth (#752) to see the system in live demonstrations.

Subsampling Explained

One of the first things we ask a new JPEG or H.264 customer about their requirements is: "What subsampling will you use?"

Many of them respond: "What's subsampling?" Here's a brief explanation.

Sampling is used to represent the Red, Blue, and Green (RBG) information defining each pixel in an image. In a group of 4 x 4 pixels, there are 16 Red samples, 16 Blue samples and 16 Green samples (48 total samples). This is called 4:4:4 format.

One technique for compressing image data is to switch the way an image is represented to a format that can more readily be subsampled.

For example, instead of using RGB, we can represent the exact same image information with values of luminance and chrominance. Luminance values are represented by Y, and chrominance by U and V. Hence this representation is called YUV format.

A perfect, lossless, transformation from RBG 4:4:4 to YUV 4:4:4 still uses the same abount of data for each pixel (16 samples for each channel). It turns out, though, that the human visual system is more sensitive to luminance than it is to chrominance.

We can exploit this fact to use fewer U and V samples -- subsampling -- but still keep the image looking pretty much the same to the human eye.

Three popular YUV subsampling schemes are 4:2:2 (24 samples), 4:2:0 (20 samples), and 4:1:1 (18 samples). They each require less data than the full 4:4:4 format, at the expense of discarding some of the image information (lossy compression). How far an image can be down-sampled and still look good depends on the nature of the image and the definition of "good" for the particular application.

Different compression algorithms work best with different image formats. So that's why one of our first questions as you consider our image and video compression IP cores is "What subsampling will you use?"

This also helps us understand if you might need something like our Color Space Converter core to get the best results in your system.