JPEG.
In computing, JPEG (pron.: /ˈdʒeɪpɛɡ/ jay-peg) is a commonly used method
of lossy compression for digital photography (image).
The degree of compression can be adjusted, allowing a selectable tradeoff between
storage size and image quality. JPEG typically achieves 10:1
compression with little perceptible loss in image quality.
JPEG compression is used in a number of image file
formats. JPEG/Exif is the most common image format used by digital
cameras and other photographic image capture devices; along with JPEG/JFIF,
it is the most common format for storing and transmitting photographic images
on the World Wide Web.[citation needed] These format variations are
often not distinguished, and are simply called JPEG.
The term "JPEG" is an acronym for the Joint
Photographic Experts Group, which created the standard. The MIME media
type for JPEG is image/jpeg (defined in RFC
1341), except in Internet Explorer, which provides a MIME type ofimage/pjpeg when
uploading JPEG images.
It supports a maximum image size
of 65535×65535.
Wikipedia reference: http://en.wikipedia.org/wiki/JPEG
TIFF
TIFF (originally standing for Tagged Image File
Format) is a file format for storing images, popular among graphic
artists, the publishing industry, and both amateur and professional
photographers in general. As of 2009, it is under the control of Adobe
Systems. Originally created by the company Aldus for use with "desktop
publishing", the TIFF format is widely supported by image-manipulation
applications, by publishing and page layout applications, by scanning, faxing, word
processing, optical character recognition and other
applications. Adobe Systems, which acquired Aldus, now holds the copyright
to the TIFF specification. TIFF has not had a major update since 1992, though
several Aldus/Adobe technical notes have been published with minor extensions
to the format, and several specifications, including TIFF/EP (ISO
12234-2), TIFF/IT (ISO 12639), TIFF-F (RFC 2306) and TIFF-FX (RFC
3949) have been based on the TIFF 6.0 specification.
Wikipedia reference: http://en.wikipedia.org/wiki/Tagged_Image_File_Format
GIFF.
The Graphics Interchange Format (GIF; /ˈdʒɪf/ or /ˈɡɪf/) is a bitmap image
format that was introduced by CompuServe in 1987 and has
since come into widespread usage on the World Wide Web due to its
wide support and portability. The format supports up to 8 bits per
pixel thus allowing a single image to reference a palette of up to 256
distinct colours. The colours are chosen from the 24-bit RGB colour
space. It also supports animations and allows a separate palette of
256 colours for each frame. The color limitation makes the GIF format
unsuitable for reproducing colour photographs and other images with
continuous color, but it is well-suited for simpler images such as
graphics or logos with solid areas of color.
GIF images are compressed using the Lempel-Ziv-Welch (LZW) lossless data
compression technique to reduce the file size without degrading the visual
quality. This compression technique was patented in 1985. Controversy over the
licensing agreement between the patent holder, Unisys, and CompuServe in
1994 spurred the development of the Portable Network Graphics (PNG)
standard. All the relevant patents have now expired.
Wikipedia reference: http://en.wikipedia.org/wiki/Graphics_Interchange_Format
PSD.
Photoshop files have default file extension as .PSD,
which stands for "Photoshop Document." A PSD file
stores an image with support for most imaging options available in Photoshop.
These include layers with masks, color spaces, ICC
profiles, CMYK Mode (used for commercial printing), transparency,
text, alpha channels and spot colors, clipping paths,
and duotone settings. This is in contrast to many other file formats
(e.g. .JPG or .GIF) that restrict content to provide streamlined,
predictable functionality. A PSD file has a maximum height and width
of 30,000 pixels, and a length limit of 2 Gigabytes.
Photoshop files sometimes have the file extension .PSB,
which stands for "Photoshop Big" (also known as "large
document format"). A PSB file extends the PSD file
format, increasing the maximum height and width to 300,000 pixels and the
length limit to around 4 Exabytes. The dimension limit was apparently
chosen arbitrarily by Adobe, not based on computer arithmetic constraints (it
is not close to a power of two, as is 30,000) but for ease of software testing. PSD and PSB formats
are documented.
Because of Photoshop's popularity, PSD files
are widely used and supported to some extent by most competing software. The .PSD file
format can be exported to and from Adobe's other apps like Adobe
Illustrator, Adobe Premiere Pro, and After Effects, to make
professional standard DVDs and provide non-linear editing and special effects
services, such as backgrounds, textures, and so on, for television, film, and
the web. Photoshop's primary strength is as
a pixel-based image editor, unlike vector-based image
editors. Photoshop also enables vector graphics editing through its
Paths, Pen tools, Shape tools, Shape Layers, Type tools, Import command, and
Smart Object functions. These tools and commands are convenient to combine
pixel-based and vector-based images in one Photoshop document,
because it may not be necessary to use more than one program. To create very
complex vector graphics with numerous shapes and colors, it may be easier
to use software that was created primarily for that purpose, such as Adobe
Illustrator or CorelDRAW. Photoshop's non-destructive Smart
Objects can also import complex vector shapes.
Wikipedia reference: http://en.wikipedia.org/wiki/Adobe_Photoshop
PNG.
Portable Network Graphics (PNG pron.: /ˈpɪŋ/ ping) is
a raster graphics file format that supports lossless data
compression. PNG was created as an improved, non-patented replacement
for Graphics Interchange Format (GIF).
PNG supports palette-based images (with palettes of
24-bit RGB or 32-bit RGBA colors), grayscale images
(with or without alpha channel), and full-color non-palette-based RGB images
(with or without alpha channel). PNG was designed for transferring
images on the Internet, not for professional-quality print graphics, and
therefore does not support non-RGB color spaces such as CMYK.
PNG files nearly always use file extension PNG or png and
are assigned MIME media type image/png; it was approved for this
use by the Internet Engineering Steering Group on 14 October
1996. PNG was published as an ISO/IEC standard in 2004.
Wikipedia reference: http://en.wikipedia.org/wiki/Portable_Network_Graphics
