AIT Portfolio Task 5Image presentations

Matthew Wong

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 ImagesRaster Images are made of

individual pixels on the screenCan also be referred to as

Bitmap imagesDependant 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 ImagesAdvantages:- 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 imageDisadvantages:- Resolution dependant, which means that pixels are

visible as the quality is reduced- File size is determined how the image is altered

Vector ImagesCreated 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 ImagesAdvantages:- 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 informationDisadvantages:- 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 formatsImage 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 - JPEGJPEG – 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 - GIFGIF – Graphic Interchange FormatDeveloped specifically for online use Ideal use for webpages since it GIF’s are cross platform and

compressedAdvantages:- 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 transparentDisadvantages:- Has a limited colour depth of 8 bits (only 256 colours)- Not suitable for natural or photographic images.

Image file formats - TIFFTagged Image File FormatLeading professional image standard.Used to archive important images because of its high

quality and flexibility for an imageAdvantages:- 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 - PNGPNG – Portable Network GraphicFor displaying colour images on the webAdvantages:- Supports transparency - Has a colour depth of 32 bits- Improved image compression- Lossless compression schemeDisadvantages:Has not been widely accepted and supported by

viewing browsers and the publicLossless compression scheme will make it have a larger

file size

Image file formats - BMPBMP – BitmapUsed as a simple graphics format for platformsAdvantages:- 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-raste

r-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