Can someone explain the DCT to me ?? - Programmers Heaven

#### Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

# Can someone explain the DCT to me ??

Guest
I have been looking at JPEG compression and i can't understand how the DCT (discret cosine transformation) works ?? Does anyone know of any decent web sites which explain it or can explain it themselves. If so mail me. Appreciated extremly cheers

Stew (MC Dreamer)

## Comments

• Posts: 1Member
: I have been looking at JPEG compression and i can't understand how
: the DCT (discret cosine transformation) works ?? Does anyone know of
: any decent web sites which explain it or can explain it themselves.
: If so mail me. Appreciated extremly cheers

: Stew (MC Dreamer)

From Wikipedia: http://en.wikipedia.org/wiki/Discrete_cosine_transform

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

Basically, as with audio compression, a DCT converts the frequency data (literal frequencies color frequencies) into a more manageable data format. It allows the compression algorithm to throw out data at specific frequencies, generally specified by some human norm. E.g. the human audio sensitivity range, or what the graphical compression algorithm deems 'reasonable' to lose.

• Posts: 6Member
Have a look at following two links to get an idea of the combination between JPEG compression and DCT

JPEG - [link=http://www.expertcore.org/viewtopic.php?f=71&t=436]JPEG Image Compression Explained[/link]

DCT - [link=http://www.expertcore.org/viewtopic.php?f=71&t=435]Discrete Cosine Transformation (DCT)[/link]
Sign In or Register to comment.