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)