A report on Data compression

Comparison of spectrograms of audio in an uncompressed format and several lossy formats. The lossy spectrograms show bandlimiting of higher frequencies, a common technique associated with lossy audio compression.
Solidyne 922: The world's first commercial audio bit compression sound card for PC, 1990
Processing stages of a typical video encoder

Process of encoding information using fewer bits than the original representation.

- Data compression
Comparison of spectrograms of audio in an uncompressed format and several lossy formats. The lossy spectrograms show bandlimiting of higher frequencies, a common technique associated with lossy audio compression.

85 related topics with Alpha

Overall

Lossy compression

30 links

In information technology, lossy compression or irreversible compression is the class of data compression methods that uses inexact approximations and partial data discarding to represent the content.

Nasir Ahmed, the inventor of the discrete cosine transform (DCT), which he first proposed in 1972.

Discrete cosine transform

20 links

A discrete cosine transform (DCT) expresses a finite sequence of data points in terms of a sum of cosine functions oscillating at different frequencies.

A discrete cosine transform (DCT) expresses a finite sequence of data points in terms of a sum of cosine functions oscillating at different frequencies.

Nasir Ahmed, the inventor of the discrete cosine transform (DCT), which he first proposed in 1972.
Illustration of the implicit even/odd extensions of DCT input data, for N=11 data points (red dots), for the four most common types of DCT (types I-IV).
336x336px
An example showing eight different filters applied to a test image (top left) by multiplying its DCT spectrum (top right) with each filter.
Original size, scaled 10x (nearest neighbor), scaled 10x (bilinear).
Basis functions of the discrete cosine transformation with corresponding coefficients (specific for our image). DCT of the image = .
On the left is the final image. In the middle is the weighted function (multiplied by a coefficient) which is added to the final image. On the right is the current function and corresponding coefficient. Images are scaled (using bilinear interpolation) by factor 10×.

The DCT, first proposed by Nasir Ahmed in 1972, is a widely used transformation technique in signal processing and data compression.

MP3

17 links

Coding format for digital audio developed largely by the Fraunhofer Society in Germany, with support from other digital scientists in the United States and elsewhere.

Coding format for digital audio developed largely by the Fraunhofer Society in Germany, with support from other digital scientists in the United States and elsewhere.

With regard to audio compression (the aspect of the standard most apparent to end-users, and for which it is best known), MP3 uses lossy data-compression to encode data using inexact approximations and the partial discarding of data.

Video coding format

14 links

Content representation format for storage or transmission of digital video content (such as in a data file or bitstream).

Content representation format for storage or transmission of digital video content (such as in a data file or bitstream).

It typically uses a standardized video compression algorithm, most commonly based on discrete cosine transform (DCT) coding and motion compensation.

Comparison of JPEG images saved by Adobe Photoshop at different quality levels and with or without "save for web"

Image compression

11 links

Comparison of JPEG images saved by Adobe Photoshop at different quality levels and with or without "save for web"

Image compression is a type of data compression applied to digital images, to reduce their cost for storage or transmission.

Advanced Video Coding

16 links

Video compression standard based on block-oriented, motion-compensated coding.

Video compression standard based on block-oriented, motion-compensated coding.

Block diagram of H.264
A YouTube video statistics with AVC (H.264) video codec and Opus audio format

AVC-Intra is an intraframe-only compression format, developed by Panasonic.

Block Diagram of HEVC

High Efficiency Video Coding

10 links

Video compression standard designed as part of the MPEG-H project as a successor to the widely used Advanced Video Coding (AVC, H.264, or MPEG-4 Part 10).

Video compression standard designed as part of the MPEG-H project as a successor to the widely used Advanced Video Coding (AVC, H.264, or MPEG-4 Part 10).

Block Diagram of HEVC
HEVC has 33 intra prediction modes

In comparison to AVC, HEVC offers from 25% to 50% better data compression at the same level of video quality, or substantially improved video quality at the same bit rate.

Lossless compression

15 links

Lossless compression is a class of data compression that allows the original data to be perfectly reconstructed from the compressed data with no loss of information.

Advanced Audio Coding

11 links

Advanced Audio Coding (AAC) is an audio coding standard for lossy digital audio compression.

MPEG logo

Moving Picture Experts Group

8 links

MPEG logo
Some well known older (up to 2005) digital media formats and the MPEG standards they use

The Moving Picture Experts Group (MPEG) is an alliance of working groups established jointly by ISO and IEC that sets standards for media coding, including compression coding of audio, video, graphics, and genomic data; and transmission and file formats for various applications.