Vector and Bitmap
Raster graphics
Raster graphic images are sometimes referred to bitmap. This is represented by rectangle grids of pixels. Raster graphics need to store a lot of information and this will result in a large file size. There are compression methods used to make the file sizes smaller.Some advantages of raster graphics are that they are fast and that you also don’t need expensive hardware to run. Another advantage is that the images are true filled areas; this means that they look really realistic to the user and overall improves the look of your image.
A disadvantage of raster graphics is that they can’t be resized very well they seem to pixelate very easily when you scale them bigger than the original image.
Vector graphics
A vector graphic is how a digital image is created through sequences of commands or mathematical equations that put lines and shapes in either two or three dimensions. Vector image files are easier to modify than raster image graphics.
An advantage of vector images is that it can be rescaled easily to any size without a loss in the quality of the image. Vector graphics also don’t use much memory on your hard disk so this saves more memory.
Vector graphics has disadvantages as they require a computer to work more for it to load up and this may affect the time taken to load your image. Another disadvantage of vector graphics is that they cant be used to display a detailed photograph.
Comparison
Overall we can see how both bitmap and vector graphics have disadvantages and advantages. A bitmap graphic is better suited for detailed photographs as they load up faster on a webpage. A vector graphic is better suited for booklets as a vector graphic doesn’t have to load up and will display a better quality image.
By using Adobe Photoshop we can save the images in different file formats. Some of the main formats that we use can be seen from the screenshot to the right. By saving these screenshot in different file formats they will show in different file sizes. From the image below
File Sizes
By using Adobe Photoshop we can save the images in different file formats. Some of the main formats that we use can be seen from the screenshot to the right. By saving these screenshot in different file formats they will show in different file sizes. From the image belowWe can see how a TIF file is the largest, with Bitmap Second. This file is substantially large compared to a standard JPEG type.
These different file types have an impact on the final product as a higher file size usually means that the overall finished product will be of a higher resolution, and more realistic.
A limitation to file sizes means that some websites will not display some types of images due to their file types. Jpeg is a commonly used file type as many websites allow Jpeg and they also have a low file size.
File Types
Jpeg – Joint Photographic Experts Group. JPEG is a standard image compression mechanism. JPEG file formats are used quite frequently as they are small in size which makes them useful as they are usually only a few hundred Kilobytes. JPEG is used for either full colour (24 bit) or grey-scale digital images. JPEG file types
GIF – (Graphics Interchange Format) is a bitmap file format which allows you to use up to 8 bits per pixel. The colours are chosen from a 24-bit RGB colour space and supports animation. The GIF file type is Mainly used for simple graphics or images such as logos with solid areas of colour,
TIFF – Tagged Image file Format (TIFF) is a file format for storing images. This file type is seen more on Apple products
PNG – PNG stands for Portable Network Graphics and It uses a lossless method of compression which means that the quality doesn’t degrade after resizing. PNG was designed for the transferring images on the internet and supports palette-based images as well as grayscale images.
Advantages and Disadvantages of JPEG and GIF Summary
Advantages of JPEG
Great format for photographs
· Many web browsers support JPEG
Disadvantages of JPEG
· JPEG uses lossy compression which means it will lose some detail when converting from other formats e.g. PNG to JPEG.
Advantages of GIF
· Uses lossless compression
· GIFs can use transparency and animation
· An image that has 256 colours or less, GIF is a good format as it will not loose any detail.
Disadvantages of GIF
· GIF has a 256 colour limit
Isn't suitable for photographs
Isn't suitable for photographs
File Compression
There are two main types of compression, lossy and lossless. I am going to discuss these now in details. File compression usually happens so that you can make more space available on your hard disk, by shortening the file sizes. WinZip is a popular program that you can zip files to lower the space that they are using.
Lossy Compression
Lossy compression is whenever the data that is used in a file is compressed and from this some of the data is lost. This means that the new version of the image will be very similar to the original, with slight variation that is unseen to the human eye. An example of this would be a JPEG file type. Lossy compression will have a smaller file size than lossless.
Lossless compression
Lossless compression is whenever the compression occurs the exact opposite from lossy. Data does not lose any quality in the process of compression. Lossless compression is better quality than lossy as if you are going to be zooming in you will not have a blurry image. Winzip will need to be used to extract the data from the compressed file.
By right clicking on a file you can compress it. This is shown to the right and this will lower the file size. By choosing the Add to .rar the file size will shrink as it will be put in a file format that has to be extracted to get the original file.
Image Resolution
Colour Depth
An advantage of file compression is that there will be more disk space available on your hard drive so that your hard drive will operate more efficient and will work faster for writing to and from the hard drive.
Disadvantages of file compression may be that you will have to keep unzipping files to use them and may not be worth compressing them in the first time. The file you are compressing will lose some of its quality while decompressing e.g. lossy compression.
By right clicking on a file you can compress it. This is shown to the right and this will lower the file size. By choosing the Add to .rar the file size will shrink as it will be put in a file format that has to be extracted to get the original file. Image Resolution
Image resolution can also be seen as dots per inch (DPI) or pixels per inch (PPI). Image resolution means how clear the image is and the more pixels that are in an image the sharper and clearer the final image will look, increasing the file size. Image resolution includes all different kinds of images like digital images or film images for example. Image resolution shows the detail that the image holds itself. A modern day laptop has a 1366x768 which mean that there are 1366 pixel horizontal and 768 vertically.
Colour depth is sometimes referred to as bit depth which describes the maximum amount of colours that are used in an image. Colour depth is the numbers of colours used in an image. The more colour depths there are in an image the more realistic it will look as it will have more colour levels available to be used. Bit depth uses 8 bits in each pixel and this can be divided up to be 3 for red, 3 for green and the last 2 for blue. If you have chosen a high quality bitmap image the colour depth will have an effect on the file size.
There are some different types of colour modes. Monochrome is white and black and this has the least amount of storage requirements – 8 pixels per byte. Grayscale is another type which has 256 different shades of grey and this is stored as one byte per pixel.
