Video Technology Magazine November 2003

Writers Wanted

Currently we are seeking people to contribute articles related to Digital Video, MPEG2, MPEG4, DVC, DVD, Streaming , Video Conferencing and related topics.
Free Advertising is also welcome.

    More info contact the Editor:
            SOKOL@VIDEOTECHNOLOGY.COM

Video Resolution of different formats

  So often I get asked about the resolution of the different video formats, With the increasing number of standards it is enough to confuse anyone. I have put together the table below based on the more common ones.

Video Conferencing Formats 4:3
FormatX and Y pixels
QCIF 176x144
QSIF 166x120
SIF320x240
CIF352288
NTSC:
4SIF
704x480
or 640x480
PAL:
4CIF
704x576 (H.261 Annex D)
16CIF 1408 x 1152
Digital Television formats 4:3
480i640x480 pixels interlaced
480p640x480 pixels progressive
DV NTSC720x480
D1 NTSC (ITU-R 601)720x486
D1/DV PAL720x576
D41440x1024
D162880x2048
Digital Television formats 16:9
720p 1280x720
1080i1920x1080 pixels
DV NTSC Wide-screen720x480
D1 NTSC Wide-screen720x486
D1/DV PAL Wide-screen720x576
Digital Television formats 8:3
D4 Anamorphic1440x1024
D16 Anamorphic2880x2048

 Wait, this isn't all of it though because the X and Y resolution is fine for a gray scale image, but what about color?
 Color is stored in RGB (Red, Green, Blue) or YUV. RGB is basically 3 images in one. A red image , and green and a blue stored into the same file, and compressed as three separate gray scale images. This is not very efficient since the Human eye is less sensitive to color then intensity.
 So in most these standards the color is recorded at 1/4 the resolution of the main image. Is is most often called YUV. Where Y is the intensity image and U and V are color components similar to Hue and Saturation on a color wheel only more complicated. This is saved or compressed as three separate images but since the U and V are 1/4 size this is a 50% reduction in size before compression even starts. YUV is considered a RAW format, although I have seen some image capture board companies try to call this a compressed format.
 Below is the chart for YUV411 where the U and V are sampled a 1/4 resolution of the gray scale image, Most JPEG images and MPEG1,2 and MPEG4 use this format.

QCIF CIF 4CIF
Luminance 176x144 352x288 704x576
Chrominance (Cb) 88x72 176x144 352x288
Chrominance (Cr) 88x72 176x144 352x288
I hope this clarifies things a bit.

More information about YUV is available at fourCC.org.

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8VSB 8-level vestigial sideband modulation

  What a mouth full. In case you didn't know 8VSB is the new transmission format for Broadcast HDTV.
Simply put, 8-VSB is the RF modulation format utilized by the approved by the FCC for the ATSC digital television standard to transmit digital bits over the airways to the home consumer. Since any terrestrial TV system must overcome numerous channel impairments such as ghosts, noise bursts, signal fades, and interference in order to reach the home viewer, the selection of the right RF modulation format is critical.
I have put together a rather extensive site containing many articles,papers and reports from the FCC on the subject. 8VSB.com

Super-thin Pliable Electronic Display


e-paper
The latest in flexible displays: Electronic circuits on a flexible stainless steel foil
   E Ink Corporation has developed a super-thin, flexible electronic-ink display screen. This team is lead by Yu Chen an electrical engineer and a visiting scientist at Princeton University in New Jersey.

Just 0.3 mm thick, the display developed by Chen and team can be flexed without distorting the type and paves the way for electronic newspapers, wearable computer screens and smart identity cards.

"It's the closest thing demonstrated today to electronic paper," says Chen.

The new display is comprised of a thin-film transistor (TFT) array. Within it's layer there are millions of tiny capsules of black and white pigments that respond to electrical charge. A negative voltage on the TFT causes white particles to move to the surface while a positive one moves black particles to the top to create the appearance of print.

Fully developed,this display can be in black and white or color. In the current form you can already display images and read books through the screen. The display is, however, currently too slow for video because of the switching speed of the electronic ink, Changing the ink arrangement takes 250 milliseconds, which is sufficient for electronic paper applications but is too slow for video displays.

The display consists of two components. The front part switches according to electronic signals and the back component is a circuit made of transistors that control each individual pixel that composes the display. Each pixel needs a circuit, made of transistors, behind it to switch it. In order to make the display flexible the transistors have to be made on a very thin and flexible substrate.

"In our case it is a very thin stainless steel foil. You need to put a layer of electronic circuits on that foil," Chen said, adding the size can vary from a business card to a computer screen. The current device is too thick to be folded in half but Chen and his team are working on a thinner a version. The current device can be rolled into a cylinder with a diameter of 4 millimeters without compromising its performance

"Our work demonstrated that you can make high-quality electronic circuits on very thin and flexible substrates," added Chen.




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