26-05-2012, 03:10 PM
Image Compression
Image Compression.ppt (Size: 935 KB / Downloads: 69)
Why Do We Need Compression
Requirements may outstrip the anticipated increase of storage space and bandwidth
For data storage and data transmission
DVD
Video conference
Printer
The bit rate of uncompressed digital cinema data exceeds 1 Gbps
Why Can We Compress?
Spatial redundancy
Neighboring pixels are not independent but correlated
Image Compression
Reduction of the number of bits needed to
represent a given image or it’s information
Image compression
exploits the fact that all images are not
equally likely
Exploits energy gaps in signal
Selected Methods for compression
LPC
Delta Modulation
Bit plane encoding
Transform encoding
Standards
JPEG
MPEG
Why Do We Need International Standards?
International standardization is conducted to achieve inter-operability .
Only syntax and decoder are specified.
Encoder is not standardized and its optimization is left to the manufacturer.
Standards provide state-of-the-art technology that is developed by a group of experts in the field.
Not only solve current problems, but also anticipate the future application requirements.
What Is JPEG?
"Joint Photographic Expert Group". Voted as international standard in 1992.
Works with color and grayscale images, e.g., satellite, medical, ...
Lossy and lossless
Image Compression.ppt (Size: 935 KB / Downloads: 69)
Why Do We Need Compression
Requirements may outstrip the anticipated increase of storage space and bandwidth
For data storage and data transmission
DVD
Video conference
Printer
The bit rate of uncompressed digital cinema data exceeds 1 Gbps
Why Can We Compress?
Spatial redundancy
Neighboring pixels are not independent but correlated
Image Compression
Reduction of the number of bits needed to
represent a given image or it’s information
Image compression
exploits the fact that all images are not
equally likely
Exploits energy gaps in signal
Selected Methods for compression
LPC
Delta Modulation
Bit plane encoding
Transform encoding
Standards
JPEG
MPEG
Why Do We Need International Standards?
International standardization is conducted to achieve inter-operability .
Only syntax and decoder are specified.
Encoder is not standardized and its optimization is left to the manufacturer.
Standards provide state-of-the-art technology that is developed by a group of experts in the field.
Not only solve current problems, but also anticipate the future application requirements.
What Is JPEG?
"Joint Photographic Expert Group". Voted as international standard in 1992.
Works with color and grayscale images, e.g., satellite, medical, ...
Lossy and lossless