Ait digital imaging

So what is Digital Imaging?
 Images are objects that can communicate a
meaning or information. Now, if an image is
transferred into a computer or a digital device, it
must be in a digital form.
 Digital Image – an image that can communicate
meaning or information digitally.
 There are two types of Digital images these of
which are Vector Images and Raster Images.

Raster Images
 Raster Images are made of
individual pixels on the screen
 Can also be referred to as Bitmap
images
 Dependant on resolution - very
difficult to resize without altering
the quality of the image
 IDEAL for natural and
photographic images that have a
high level of detail with complex
colours and tones.

Raster Images
 Advantages:
- Ideal for natural and photographic images with high level
of detail
- Maintains image quality with a reduced file size
- Easy to edit which is a plus for users that digitally
manipulate images
- Easy to alter the colour of the image
 Disadvantages:
- Resolution dependant, which means that pixels are visible
as the quality is reduced
- File size is determined how the image is altered

Vector Images
 Created on the computer using
mathematical calculations to
make a line or a curve.
 Are NOT resolution dependant –
resizing the image will not affect
the quality of the it.
 IDEAL for simple geometric
shapes and logos and
typefaces

Vector Images
 Advantages:
- Much more flexible than raster images
- NOT resolution dependant – quality does not change when
image is resized
- File size is smaller than Raster images since they produce
less information
 Disadvantages:
- In order to be viewed on a monitor, they must be converted
to become a raster image.
- Since computer monitors can only show pixels
- The computer has to recalculate the vector images every
time it is refreshed.

Image file formats
 Image file formats are images that have been stored
using a specific file format. This allows the computer
to tell what type/kind of data is stored within the
image file.
 IMAGE FILE FORMATS
- .jpg
- .tif - TIFF
- .bmp - bitmap
- .gif
- .png

Image file formats - JPEG
 JPEG – Joint Photographic Expert Group
- Developed specifically to provide a suitable format for the storage of
photographic and photo-realistic images
- For photographic and image files
 Advantages:
- Gives very high compression ratios
- Used for highly detailed, natural, art or photographic images
- Acceptable in most websites
- Great for transmitting across different Media
 Disadvantages:
 Compression is cumulative – this means that everytime it is
compressed over and over again, the quality is lost as data keeps on
being removed
 Mainly designed for websites and emails.

Image file formats - GIF
 GIF – Graphic Interchange Format
 Developed specifically for online use
 Ideal use for webpages since it GIF’s are cross platform and compressed
 Advantages:
- Best for images with a large area of solid colours. E.g shapes, logos and
text
- Designed to produce small files. Hence, the best file format for
transmit over the net
- Can be interlaced and animated
- Can be set to be transparent
 Disadvantages:
- Has a limited colour depth of 8 bits (only 256 colours)
- Not suitable for natural or photographic images.

Image file formats - TIFF
 Tagged Image File Format
 Leading professional image standard.
 Used to archive important images because of its high
quality and flexibility for an image
 Advantages:
- Lossless – image resolution does not change after being
modified
- Quality of the image is very high
- Good for photo-realistic images
 Disadvantages:
- File size is very large
- Not a suitable format for the web

Image file formats - PNG
 PNG – Portable Network Graphic
 For displaying colour images on the web
 Advantages:
- Supports transparency
- Has a colour depth of 32 bits
- Improved image compression
- Lossless compression scheme
 Disadvantages:
 Has not been widely accepted and supported by viewing
browsers and the public
 Lossless compression scheme will make it have a larger file
size

Image file formats - BMP
 BMP – Bitmap
 Used as a simple graphics format for platforms
 Advantages:
- Free of patents
- Pixel values can be modified individually or as large groups.
 Disadvantages:
- Can’t be used to transfer files over the net
- Very large file size
- Can’t be compressed (typically)

References
 Images:
 http://www.webcoursesbangkok.com/wp-content/uploads/2010/10/image-raster-
leaves.jpg - visited 16/3/12
 http://www.smashingapps.com/wp-content/uploads/2008/01/logo-templater-snap.jpg -
visited 16/3/12
 http://vector-conversions.com/images/raster_vs_vector_1.jpg - visited 16/3/12
 http://garcya.us/wp-content/uploads/2007/07/16-Free-Real-Estate-Vector-Logo-
types.jpg - visited 16/3/12
 Information:
- Groups.esa.edu.au – Applied information technology course outline 2A
- Documents used:
- Raster v Vector
- Image file formats
- Digital Image basics
- http://userwww.sfsu.edu/~pbwong/groupproject/ad_dis.html - visited 16/3/12
- http://www.fileformat.info/mirror/egff/ch03_08.htm - visited 16/3/12

Ait digital imaging

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