P5
Vector graphics are different from bitmap graphics. The main features of vector graphic is that when the image is enlarged, it doesn't loss print quality, small file size when saved to disk, objects van be grouped together, each object has outline and or fill and most vector images are made from circles and rectangles. For example diagram images such as the program Visio.
Vector is objects that have coordinate points and use mathematics inside the software to calculate how to display the image
Bitmap graphics are different from vector graphics. The features of bitmap are:
▫ Large file size when saved on a disk.
▫ Bitmap when scanned into a computer system can create a picture using a scanner or a digital camera.
▫ Print quality can become blocky when enlarged and will reduce the picture quality.
Bitmap is good for print screens and web page illustrations.
When using a website it is essential that file size consider Minimising file sizes in websites are essential. Some file sizes are too big and may take too long to download. Many users lose patience and navigate away. When changing the file size the resolution always alters. It losses quality as files are compressed, but not always noticeable when viewed at smaller sizes such as a VDU screen. For example every video on YouTube has been compressed. Resolution is the number of pixels per inch in an image. High quality images usually have a large file size, and normally have a high resolution. This has an effect on the download time.
Special techniques used to manage file sizes are frame disposal and autocrop. Optimisation of animation files is a complex process as it involves a lot of detail in the file type.
Frame disposal is to prevent unwanted visible elements in a picture or animation (artefact) appearing. This is when the previous frame is visible in the picture through the transparent areas of subsequent frames. To avoid this happening frames should be disposed and the background restored. A method such as frame disposal is very handy when working with animation.
Autocrop is a function that removes unwanted edge from an image or animation. Autocropping can make sure only the necessary area of the image is visible. This can also minimize the size of the file.
When animating for the web the file size is not the only constraint, in this medium. Although the animation is not the focal point it is however used to enhance the content of the site. E.g. logos and buttons. In order for the animations to blend into the site as a whole, a house style may have to be followed. This is a design that is carried out throughout a business’s website. A house style can also be extended throughout all the publications of that organisation including logos, colour combinations and layouts.
Buttons such as animated rollovers are buttons that perform an action when an event triggers them. E.g. when a mouse hovers over the icon. The file size of the animation has to be a reasonable size. This is because if it’s to big the browser will take longer to load and users may get bored. The designer of the animation has to make sure the animation works on every monitor size or platform. This means even if the monitor size is different the user will still be able to see it without scrolling up and down or side to side. Internet connection speed also can affect the animation for the web. For example if the internet speed is to slow the animation will be slow and jerky. The designer must think about the speed of the internet connection this is why most of them generally use .Gif for web animation and therefore playable on most platforms.
Gif- GIF is stands for graphics interchange format. This file stores graphical images up to 256 colours. GIF animation compresses images which can loss the quality of the image. Most GIF images are used extensively on web animation and therefore playable on most platforms.
Sound also influences the performance of a website.
reference
http://www.underwaterphotography.com/photoshop/photoshop/help.html
