JPEG compression

JPEG Compression vs. File Size
and Image Quality
This photo CD image was opened with Adobe Photoshop using their Kodak Photo CD conversion program. It was then sized and saved to JPG using Adobe's "best" level of image quality for compression.

Megabytes, Megapixels, JPEG Compression, and File Size Confusion
Isn't 100K a really small size for a photo for Your Best Shot? We explain JPEG compression, from camera to computer monitor.
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JPEG Compression and Noise Reduction
JPEG compression squares are normally hard to notice in uniform surfaces at high quality levels.

JPEG Compression
A (pronounced jay-peg) stands for Joint Photographic Experts Group. JPEG is a color image compression technique that reduces file sizes by eliminating redundant or unnecessary image data.

JPEG compression
A standard developed by JPEG for reduction in the amount of data required to represent an image and therefore the hard disk space needed to store it.

JPEG compression artifacts blend well into photographs with detailed non-uniform textures, allowing higher compression ratios.
Full quality (Q = 100), filesize 83261 B.
High quality (Q = 50), filesize 15138 B.

JPEG compression goes through a number of steps to reduce the file size. First, the file is changed from an RGB model to a luminance/chrominance model (one channel of tonal information and two channels of color information).

On the left, 10:1 JPEG compression. On the Right 40:1 compression.
Uncompressed the image would look virtually identical to the 10:1 JPEG on the left.

JPEG Compression
Demosaicing and white balance involve interpreting and converting the bayer array into an image with all three colors at each pixel, and occur in the same step.

For example, when a typical camera is set to record a JPEG, it's actually recording an EXIF file that uses JPEG compression to compress the photo data within the file.

Rainier after being subjected to repeated JPEG compression
The image above contains four versions of Mt. Rainier, one of my favorite subjects. Obviously since you're reading this on a web page, the entire image is itself a JPEG.

TIFF/ EP may be stored by the camera in uncompressed form, or using JPEG compression. TIFF/EP image files are often stored in a "read-only" fashion to prevent accidental loss of important information contained within the file.

A very similar argument is also heard about JPEG compression. There is a gnawing fear that somehow because JPEG is a "lossy" compression algorithm you'll be throwing away that vital pixel.

JPEG compression throws away some of the information your sensor captured and that's the nature of the beast. But with point-and-shoot cameras you have a further culprit " overly aggressive noise reduction.

Congratulation, you discovered the JPEG compression. In JPEG one of the trick to compress picture is to save the color parts of the image in much lower resolution than intensity.

Its name derives from the name of the people who developed the JPEG compression technique: the Joint Photographic Experts Group. Common file extensions associated with this format are .jpg, .jpeg.

JPEG compression degrades image quality and can even introduce artifacts into your image.

Short for Exchangeable Image File, a format that is a standard for storing interchange information in digital photography image files using JPEG compression.

JPEG compression can vary from nearly lossless to highly lossy. All digital cameras are capable of capturing images in JPEG format, and because JPEG is a standard, JPEG image files can be read by all image-processing software.

RAW, JPEG, and TIFF: what's the difference?
JPEG Compression Details and Facts: although an older article, the author offers valuable advice and information regarding JPEG technology
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Jpeg quality
This parameter controls the JPEG compression rate used when saving the images.
Higher quality leads to a larger file size.
Scratch drive
The Scratch drive is the drive used to swap data when there is not enough memory.

JPEG2000 - The new JPEG compression standard that will be used in digital cameras and software starting in 2002 (maybe?). It will feature higher compression but with less image quality loss.

JPEG - 2000 . The new JPEG compression standard that may start to be used in digital cameras and software. It will feature higher compression with less image quality loss.

The image is taken in the same condition but saved at four different JPEG compression modes (Photoshop 5.5 quality levels) and we can see that the more compression, the more distortion.

Joint Photographic Experts Group. A common method of image compression. JPEG compression is said to be 'lossy', detail is permanently lost each time the image is edited and saved.
Mb
Megabytes.

Digital cameras generally use JPEG compression to pack more images onto memory cards.

JPEG compression provides the best results with continuous-tone images, such as photographs, when the size of the file is an important factor.
JPEG images are stored with a file extension name of JPG or JPEG. Jupiter Fifth planet from the Sun.

A JPEG image file name carries the extension "jpg". JPEG compression is "loosy", meaning it looses some image information as opposed to other formats like TIFF. A "high quality" JPEG file looses less than a "low quality" JPEG file.

EXIF - Short for 'Exchangeable Image File' and refers to the file format used by most digital cameras. For example, when a typical camera is set to record a JPEG, it's actually recording an EXIF file that uses JPEG compression to compress the ...

A file format using wavelet based image compression which offers high compression ratios without the image degradation associated with standard JPEG compression.
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The letters JPEG stand for Joint Photographic Experts Group that describes a digital image file format standard in which the size of the file is reduced by compression. A JPEG image file name carries the extension "jpg". JPEG compression tends to ...

DSP
Short for Digital Signal Processor, electronical Microprcessor for real-time editing from digital signals. A DSP can take over one or more functions (f.i. Autofocus. JPEG compression, Connection ).

EXIF Exchangeable image file. The file format used by most digital cameras. A camera set to record a JPEG is actually recording an EXIF file that uses JPEG compression to compress photo data within the file.

These settings can be equated to a quality level parameter of jpeg compression. If the quality level gets down into the 60 percent range, you might start to notice little squiggles and extra graininess.

some color channels - notably the blue channel - will be more affected by noise than others. This is because sensors are often less sensitive to blue light, and to compensate for this the blue channel is amplified more than others. JPEG compression ...

The technique used in JPEG compression allows the user to select the compression ratio. High-compression ratios generally result in low image quality.

See also: Compression, Image, JPEG, Camera, Digital