JPEG Compression Method?

Question

I am doing some research into JPEG compression and was wondering can anyone help me with these questions?

What company, angency, group or other bodies created or maintain the standard?
For what kind of data is the format designed? What is its purpose?
What advantage does the format have? For what data is it best used?
What disadvantages does the format have? For what data does it not work well?
How does the method work?

Answer 1

Jpeg is designed for photographs; converting rasterised bitmaps into a smaller filesize to send across the internet. It is best used for bitmap photos.
Its advantage is that it can speed up the time needed to send even large images.
Its disadvantage is that to achieve high rates of compression on larger pictures, image quality is lost and cannot be recovered. So its not like zipping a file, which you can then unzip. It changes the image.
It does not work well for vector style graphics, or those with large flat areas of colour; as it 'dithers'. You end up with a degraded image. It does not support transparency either. Giffs or Pings are better for graphics.

How Jpegs work; imagine you have a grid and each cell in the grid is one pixel. To make a photo you have millions of colours. You also have thousands of shades of each colour.
Bitmap looks along the first row and writes '1 black, 1 black, 1 black, 1 red, 1 red'.
Jpeg writes '3 black, 2 red'.

Answer 2

The name JPEG stands for Joint Photographic Experts Group, the name of the joint ISO/CCITT committee which created the standard. The group was organized in 1986, issuing a standard in 1992 which was approved in 1994 as ISO 10918-1.........

This filetype has the lowest filesizes but compression artifacts may be visible as you lower the quality option, since JPEG is a lossy format, the quality loss is especially easy to see on sharp borders, on smooth borders and shading, like photos or realistic looking drawings, the quality loss is barely notable, if you choose a high JPEG quality. After you saved an image as JPEG, you should not open, change and save it as JPEG again, since it makes the image's quality drop dramatically.

For a more detailed look check out the links below...

http://en.wikipedia.org/wiki/Jpeg
http://www.answerbag.com/q_view.php/3455

Good Luck!!

Answer 3

JPEG stands for 'Joint Photographic Experts Group' and was designed for Picture. It was created by the joint ISO/CCITT committee in 1986, issuing a standard in 1992 which was approved in 1994 as ISO 10918-1 and JPEG itself specifies only how an image is transformed into a stream of bytes, not how those bytes are encapsulated in any particular storage medium and is most used for storing and transmitting photographs on the World Wide Web its disadvantage is that if you don’t save it in good format, the picture will look blunt. And it works well. Or visit http://en.wikipedia.org/wiki/JPEG, www.jpeg.org/committee.html for more info.

Answer 4

who didnt do their homewrok then?

ok Jpeg file compression. (joint photographic expert group) or something like that.

it takes a raw image and compresses it by using keyed area codes..ir black is area 1, unlike bitmaps where every pixel had and address. a jpeg is a variable compression tool. it can atke a 5meg raw/bitmap and shrink it to 2 meg or less.

the compression reduces clarity and quality in the original image, that cannot be undone. when you get it wrong, you end up with a square oixelated image, thats no good to man or beast.

its a graphic application. used in camera phones and digital cameras...i have an 8meg Olympus E500. unzipped the raw format is 35 megs an image...as a jpeg its around 4-5megs.

you couldnt use ot for music compression...or word docs...

there you go, i spent years learning this, im a photographer..ive pointed you in the right direction...and you can finish it easily...