Image File Formats
Image file formats refers to the organizing and storing digital images. The images may be taken from the digital camera, scanned from the scanner or drawn in any image processing software. The image file is stored in the secondary device for future use. It may be saved either compressed mode or in uncompressed mode. The file which is saved in uncompressed mode will be in big sized. The bytes present in the opened mode will be equal in the saved mode also. But in the compressed mode the size of the bytes will be less than in opened mode.
There are two types of compressed mode. Lossless and Lossy. Lossy algorithm uses compression algorithm with some bytes throwing from the file to make the size small. When we open it the thrown bytes or pixels will not be recovered again. In this case the quality of the image will be degraded. We see the zigzag or boxes in the image when enlarged.
In the other hand the lossless compression the compression algorithm is such that the file will be compressed and the bytes will be less in the saved file but when opened all the bytes will present as it was before compressed. Here data will not be lost and the quality of the image will not be degraded.
There are hundreds of image file types. The PNG, JPEG, and GIF formats are most often used to display images on the internet. Some of these graphic formats are listed and briefly described below, separated into the two main families of graphics:
a. Raster format b. Vector format
In addition to straight image formats, Metafile formats are portable formats which can include both raster and vector information. Examples are application-independent formats such as WMF ( Windows MetaFile ) and EMF ( Enhanced MetaFile ). The metafile format is an intermediate format. Most applications open metafiles and then save them in their own native format. Page description language(PDL) refers to formats used to describe the layout of a printed page containing text, objects and images. Examples are PostScript.
Raster formats and types
Raster formats are based on pixels. Pixel is an unit of an image or a dot in an image. A raster image is developed by the dots. The demerit of a raster file is when a file is enlarged we see the stair cases in the image. Stair cases are rectangle blocks, which makes the image not clear or blur.
JPEG(Joint Photography Experts Group) is a lossy compression method, JPEG compressed images are usually stored in the JFIF (JPEG File Interchange Format) file format. The JPEG/JFIF filename extension is JPG or JPEG.
JPEG 2000 is a compression standard enabling both lossless and lossy storage. Loss less doesn’t lose any bytes while compressing but lossy loses some pixel while compressing. The compression methods used are different from the ones in standard JFIF/JPEG; they improve quality and compression ratios, but also require more computational power to process. JPEG 2000 also adds features that are missing in JPEG. It is not nearly as common as JPEG, but it is used currently in professional movie editing and distribution (some digital cinemas, for example, use JPEG 2000 for individual movie frames).
The Exif (Exchangeable image file format)format is a file standard similar to the JFIF format with TIFF extensions; it is incorporated in the JPEG-writing software used in most cameras.
The TIFF (Tagged Image File Format) format is a flexible format that normally saves eight bits or sixteen bits per color (red, green, blue) for 24-bit and 48-bit totals, respectively, usually either the TFIF or TIF filename extension
The GIF (Graphics Interchange Format) is in normal use limited to an 8-bit palette, or 256 colors (while 24-bit color depth is technically possible). Due to it’s animation capabilities, it is still widely used to provide image, animation effects, despite its low compression ratio compared to modern video formats.
The BMP file format (Windows bitmap) handles graphic files within the Microsoft Windows OS. Typically, BMP files are uncompressed, and therefore large and lossless; their advantage is their simple structure and wide acceptance in Windows programs.
The PNG (Portable Network Graphics) file format was created as a free, open-source alternative to GIF.
PPM, PGM, PBM, and PNM
Netpbm format is a family including the portable pixmap file format (PPM), the portable graymap file format (PGM) and the portable bitmap file format (PBM),
WebP is a new open image format that uses both lossless and lossy compression. It was designed by Google to reduce image file size to speed up web page loading :its principle purpose is to supersede JPEG as the primary format for photographs on the web.
The High Efficiency Image File Format ( HEIF) is an image container format that was standardized by MPEG on the basis of the ISO base media file format.
BPG ( Better Portable Graphics ) is a new image format. Its purpose is to replace the JPEG image format when quality or file size is an issue. Its main advantages are:
a. High compression ratio. Files are much smaller than JPEG for similar quality.
Other raster format
a. DRW ( Drawn File )
b. ECW ( Enhanced Compression Wavelet )
c. FITS ( Flexible Image Transport System )
d. FLIF ( Free Lossless Image Format )
[ Note: when you open a vector file in photoshop it converts into raster. ]
As opposed to the raster image formats above (where the data describes the characteristics of each individual pixel ), vector image formats contain a geometric description which can be rendered smoothly at any desired display size.
At some point, all vector graphics must be rasterized in order to be displayed on digital monitors. Vector images may also be displayed with along CRT technology such as that used in some electronic test equipment, medical monitors, radar displays, laser shows and early video games. Plotters are printers that use vector data rather than pixel data to draw graphics.
These are formats containing both pixel and vector data, possible other data, e.g. the interactive features of PDF.
a. EPS ( Encapsulated PostScript )
b. PDF ( Portable Document Format )
c. PostScript, a page description language with strong graphics capabilities
d. PICT ( Classic Macintosh Quickdraw file )
e. WMF / EMF ( Windows Metafile / Enhanced Metafile )
f. SWF ( Shockwave Flash )
g. XAML User interface language using vector graphics for images.
Stereophonic sound or, more commonly , stereo, is a method of sound reproduction that creates san illusion of multi-directional audible perspective. This is usually achieved by using two or more independent audio channels trough a configuration of two or more loudspeakers ( or stereo headphones ) in such a way as to create the impression of sound heard from various directions, as in natural hearing.
a. MPO The Multi Picture Object ( .mpo ) format consists of multiple JPEG images (Camera and Image Products Association) ( CIPA ).
b. PNS The PNG Stereo ( .pns ) format consists of a side-by-side image based on PNG ( Portable Network Graphics ).
c. JPS The JPEG Stereo ( .jps ) format consists of a side-byside image format based on JPEG.
1. Answer the following questions.
a. What do you mean by graphics?
b. What is pixel?
c. How graphic images are created?
d. What is the difference between raster and vector? Explain with figure.
e. Why jpg file format is mostly used in internet?
f. Where the vector files are used?
g. What do you mean by Stereo formats?
2. Fill in the blanks.
a. Graphics is related with the ________________ in the computer.
b. Raster formats are based on ________________ .
c. JPEG is an example of lossy___________ file format.
d. A vector image formats contain a ________________________ description which can be rendered smoothly at any desired display size.
e. The full form of PCL is __________________________________ .
3. Write true or false.
a. Graphics is related with images. __________
b. Lossy file compression means the files which will be lost and we cannot retrieve it again. _____
c. Vector files do not loose their image quality when enlarged. _______
d. BMP file is a vector file format. __________
e. BMP file cannot be compressed. _______
4. Choose the correct answer.
a. Plotters use ___________ data.
i. Raster ii. Vector iii. All 1 and 2 iv. None of above
b. Zigzag saw or staircases are found in
i. Vector ii. Raster iii. Text iv. No where
c. Which file format is best for web?
i. Bmp ii. Jpg iii. Png iv. Psd
d. GIF has _________ bit color
i. 8 ii. 16 iii. 24 iv. 128
e. _____________ Formats are portable formats which can include both raster and vector information.
i. PCL ii. Jpg iii. WMG iv. TIF
5. Write the full form of the following.
PNG, JPEG, GIF, WMF, EMF, PDL, PCL, LZW, BMP, PNM, HDR, HEIF, BAT, BPG, FLIF
6. Write the technical terms of the following.
a. Which is related with images in the computer. ______________________________
b. The formats that contain a geometric description which can be rendered smoothly at any desired display size. __________________________________
c. The formats containing both pixel and vector data, possible other data, e.g. the interactive features of PDF. _____________________________
d. A method of sound reproduction that creates an illusion of multi-directional audible perspective. _________________________________