- Adobe Photoshop (*.psd)
Adobe Photoshop (PSD) is the format produced by the Adobe Photoshop
- Tagged Image File Format (*.tif, *.tiff)
TIFF (Tag Image File Format), pronounced "tiff," was originally
developed by Aldus Corporation to save images created by scanners,
frame grabbers, and photo editing programs. This format has been widely
accepted and widely supported as an image transfer format not tied
to specific scanners, printers, or computer display hardware. TIFF
is also a popular format for desktop publishing applications. There
are several variations of the format, called extensions, so you may
have occasional problems opening one from another source. Some versions
are compressed using the LZW or other lossless methods. TIFF files
support up to 24-bit colors.
- PCX Image format (*.pcx)
This is a file format created by ZSoft. This format compresses its
image data with the RLE type compression.
- JPEG image (*.jpg, *.jpeg)
The JPEG (Joint Photographic Experts Group) format, pronounced "jay-peg,"
is by far the most popular format for display of photographic images
on the Web. The term "JPEG" is often used to describe the
JFIF file format (JPEG File Interchange Format). JFIF is the actual
file format that contains an image compressed with the JPEG method.
These newer JFIF files originally used the JPG extension, however,
the latest standard calls for using a JIF extension instead. The format
is optimized for the display of photographs and doesn't work as well
as GIF for type or line drawings (GIF is optimized for those). JPEG
images have two distinctive features:
JPEG uses a lossy compression scheme but you can vary the amount
of compression and hence trade off file size for image quality, even
making extremely small files with poor quality.
JPEG supports 24-bit color. GIF, the other format widely used on the
Web supports only 8-bits.
Compression is performed on blocks of pixels eight on a side. You
can see these blocks when you use the highest levels of compression
or greatly enlarge the image. JPEG is a two pass compression and de-compression
algorithm. This means it take longer to load and display than a gif
file. You can save images in a progressive JPEG format that works
somewhat like an interlaced GIF. While a standard JPEG loads from
top to bottom, a progressive JPEG displays the entire image starting
with the largest blocks. This allows the image to be displayed first
in low-resolution and then filled in as more data arrives. When you
save an image in this format, you can specify the number of progressive
scans. Don't use JPEG to save original images you expect to modify
later. Every time you open one of these files, and then save it again,
the image is compressed. As you go through a series of saves, the
image become more and more degraded. Be sure to save your originals
is a loss-free format such as TIFF or BMP at maximum color depth.
Also, when you save an image as a JPEG, the image on the screen won't
reflect the compression unless you load the saved version.
- Portable Network Graphics (*.png)
PNG (Portable Network Graphics), pronounced "ping," has
been developed to replace the aging GIF format and it is supported
by both Microsoft Internet Explorer and Netscape Navigator. PNG, like
GIF is a lossless format, but it has some features that the GIF format
doesn't. These include 254 levels of transparency (GIF supports only
one), more control over image brightness, and support for more than
48 bits per pixel. (GIF supports 8 for 256 colors). PNG also supports
progressive rendering, as interlaced GIFs do, and tends to compress
better than a GIF.
- Windows Bitmap (*.bmp)
BMP, pronounced a letter at a time "B-M-P," files use a
Windows bitmap format. These images are stored in a device-independent
bitmap (DIB) format that allows Windows to display the bitmap on any
type of display device. The term "device independent" means
that the bitmap specifies pixel color in a form independent of the
method used by a display to represent color. The default filename
extension is .BMP and these files come in two formats:
The OS/2 format is not compressed (RGB encoded). RGB encoding supports
Windows BMP and DIB files may be saved using no compression (RGB encoded),
or using run length encoded lossless compression (RLE encoded). RLE
supports only 256 colors.
Windows can store color data along with the image it affects. When
stored like this, the images is called a Microsoft Device Independent
Bitmap, or DIB. When written out to a file, it in the Microsoft Bitmap
Format, or BMP. References to the DIB file format actually refer to
Windows RLE files are Windows DIB files that use RLE compression.
Using RLE compressions to save an image as a DIB or BMP, produces
an RLE file. The only difference is the filename extension.
- True Vision Targa (*.tga)
TGA or TARGA format is a format for describing bitmap images, it
is capable of representing bitmaps ranging from black and white, indexed
colour, and RGB colour, the format also supports various compression
methods. This note describes the minimal requirements for creating
a TGA file for a 24 bit RGB uncompressed colour image, this covers
most applications where a developer might want to create an image
for another package which reads TGA files
- Compuserve GIF(*.gif)
GIF (Graphics Interchange Format) format images, pronounced "jiff,"
are widely used on the Web but mostly for line art, not for photographic
images. This format stores up to 256 colors from an image in a table
called a palette. Since images have millions of colors, a program
such as PhotoShop selects the best ones to represent the whole when
you save the image in this format. When displayed, each pixel in the
image is then displayed as one of the colors from the table, much
like painting by numbers.
There are two versions of GIF in use on the Web; the original GIF
87a and a newer GIF 89a. Both versions can use interlacing; storing
images using four passes instead of one. Normally, when an image is
displayed in a browser, it is transmitted a row at a time starting
at the top row and filling in down the page. When saved as an interlaced
GIF, it is first sent at its full size but with a very low resolution.
This allows a person to get some idea of all of the contents of the
image file before it is completely transmitted. As more pixels are
sent in the next three passes the image fills in and eventually reaches
its full resolution. The newer GIF 89a version adds some additional
capabilities that include the following:
Image backgrounds can be made transparent. To do so, you specify which
color in the table is to be transparent. When viewed with a Web browser,
the browser replaces every pixel in the image that is this color with
a pixel from the web page's background. This allows the background to
show through the image in those areas. You have to choose the transparent
color carefully. If you select one that occurs anywhere in the image
besides the background, your image will appear to have "holes"
Images can be animated. By rapidly "flipping" through a series
of images, objects can be animated much as a movie simulates motion
using a series of still images. This works best with line drawings but
can also be done with photographs. Depending on bandwidth, the animation
may not work the first time. However, once it's stored in cache and
replayed, it will work fine.
GIF images are limited to a maximum of 256 colors. These colors, stored
in a table, index, or palette, are often referred to as indexed colors.
When you convert a photograph to GIF format, most graphics programs
will allow you to dither it. This replaces lost colors with patterns
of those available in the palette. Dithering improves the appearance
of the image, but it also increases the size of the file. Although GIF
photographs often look OK on-screen, they suffer if compared side-by-side
with images saved in JPEG and other formats. The GIF format is best
used for line art such as cartoons, graphs, schematics, logos, and text
that have a limited number of colors and distinct boundaries between
color regions. GIF images are compressed using a "lossless"
form of compression called LZW (Lempel-Ziv-Welch). The amount of compression
achieved depends on the frequency of color changes in each pixel row.
This is because when two or more pixels in a row have the same color,
they are recorded as a single block. Hence, a picture of horizontal
stripes will compress more than one of vertical stripes, because the
horizontal lines would be each stored as a single block. Photographs
with large areas of identical colors such as skies, snow, clouds, and
so on, will compress more than images with lots of colors and patterns.
To save a 24 bit image as a GIF, you must reduce the bit depth down
to 8 bits. To reduce file sizes in GIF format, you can further reduce
the number of colors in the image. This is difficult with most photographs,
but not with line art. For example, if your image has 16 or fewer colors,
you can convert it to a 4-bit (16-color) palette. Most graphics programs
will allow you to do this. Even with photographs you can sometimes reduce
the image to fewer colors than actually exist without noticeable loss.
The discarded colors are those that are seldom-used or transitional
colors between more frequent colors. When working with grayscale images,
GIF works as well as JPEG because almost all programs use 8-bits (256
colors) for gray scale images.
Video formats: (Note: Unique feature!!!)
- Video for Windows(*.avi)
AVI format Description
One of the oldest formats in the x86 computer world is AVI.
The abbreviation 'AVI' stands for 'Audio Video Interlaced'.
This video format was created by Microsoft, which was
introduced along with Windows 3.1. AVI, the proprietary format
of Microsoft's "Video for Windows" application,
merely provides a framework for various compression algorithms
such as Cinepak, Intel Indeo, Microsoft Video
1, Clear Video or IVI. In its first version,
AVI supported a maximum resolution of 160 x 120 pixels with
a refresh rate of 15 frames per second. The
format attained widespread popularity, as the first video
editing systems and software appeared that used AVI by default.
Examples of such editing boards included Fast's AV Master
and Miro/Pinnacle's DC10 to DC50. However, there were a number
of restrictions: for example, an AVI video that had been processed
using an AV Master could not be directly processed using an
interface board from Miro/Pinnacle. The manufacturers adapted
the open AVI format according to their own requirements.
AVI is subject to additional restrictions under Windows 95,
which make professional work at higher resolutions more difficult.
For example, the maximum file size under the FAT16 file system
is 2 GB. The FAT32 file system (came with OSR2 and Windows
98) brought an improvement: in connection with the latest
DirectX6 module 'DirectShow', files with a size of 8 GB can
(at least in theory) be created. In practice however, many
interface cards lack the corresponding driver support so that
Windows NT 4.0 and NTFS are strongly recommended. Despite
its age and numerous problems, the AVI format is still used
in semi-professional video editing cards. Many TV cards and
graphic boards with a video input also use the AVI format.
These are able to grab video clips at low resolutions (mostly
320 x 240 pixels).
AVI is a file format, like MP3 or JPG. But unlike
these formats, AVI is a container format, meaning it can contain
video audio compressed using many different
combinations of codecs. So while MP3 and JPG can only contain
a certain kind of compression (MPEG Audio Layer 3 and JPEG),
AVI can contain many different kinds of compression (eg. DivX
video + WMA audio or Indeo video + PCM audio), as long as
a codec is available for encoding/decoding. AVI all look the
same on the "outside", but on the "inside", they may be completely
different. Almost all tools on this site are not just DivX
tools, but also AVI tools, so will probably work with
other codecs. There is no such thing as a "normal" AVI file,
but the closest you can get is probably an AVI file that contains
no compression. AVI files has been around since the time of
Windows 3.1, so by no means is it a new thing, and is probably
the most common video format around (although its popularity
wavered a few years ago, but has since come back with a vengeance
due to the emergence of DivX). AVI files may also have
limits under Windows 95/98, and for more information, please
read this article. Note that AVI files without file limits
(other than the Windows Fat32 file limit) are usually referred
to as OpenDML AVI files.
- MPEGG Video File Format (*.mpg, *.mpeg)
MPEG-4 is an ISO/IEC standard developed by MPEG (Moving Picture Experts
Group), the committee that also developed the Emmy Award winning standards
known as MPEG-1 and MPEG-2. These standards made interactive video
on CD-ROM, DVD and Digital Television possible. MPEG-4 is the result
of another international effort involving hundreds of researchers
and engineers from all over the world. MPEG-4, with formal as its
ISO/IEC designation 'ISO/IEC 14496', was finalized in October 1998
and became an International Standard in the first months of 1999.
The fully backward compatible extensions under the title of MPEG-4
Version 2 were frozen at the end of 1999, to acquire the formal International
Standard Status early in 2000. Several extensions were added since
and work on some specific work-items work is still in progress.
MPEG-4 builds on the proven success of three fields:
Interactive graphics applications (synthetic content);
Interactive multimedia (World Wide Web, distribution of and access
MPEG-4 provides the standardized technological elements enabling the
integration of the production, distribution and content access paradigms
of the three fields.
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