Features and limitations of graphical file formats

Types of file formats

Their are two main categories of graphical file format. They are bitmap files (also known as raster files) and vector files.

Bitmap File

A bitmap file is also known as a raster file. This type of file is best suited for the use real images such as photographs. A bitmap file is made up of millions of tiny pixels which are then outputted onto a digital device such as a monitor or a mobile phone. Their are many different types of bitmap file. A few examples of this would be .PSD, .PNG, .GIF and, .JPEG. Bitmap files are faster at loading as have a low data space size in comparison to a vector file. This makes them more suited for the use on websites. Another advantage of a bitmap file would be that they look a lot more realistic than vector files and that the refresh rate is more independent of the screens complexity. Their are however some disadvantages of bitmap files. They are unable to be scaled effectively and they become more and more pixalated the larger you make the image.

Jpeg

A Jpeg image falls into the category of being a bitmap file. JPEG stands for joint photographic experts group and the extention name is .JPEG.  A JPEG image is a standard image compression mechanism. It has been made to compress realistic looking photos such as a 24 bit full colour image or grey scale images of realistic scenes. A JPEG image works extremely well with realistic scenes such as photographs etc and is popular on many websites as all internet browsers support this type of file format. It does however not work as well with images such as cartoon artwork or letters because the image size is usually extremely large. 

GIF

A GIF image is another type of bitmap image file. GIF stands for Graphics Interchange Format. A GIF image file can support an image of up to 8 bits per pixel. This means that a GIF image can have up to 256 different colours that are chosen from a 24 bit RGB (Red, Green, Blue) to create the colour for the images which is a slight disadvantage. A GIF image is suitable for moving animations because it supports more than one frame and you can have a transparent background meaning that the image can blend in well with the background. A GIF image is also quite popular on websites and for moving images Below is an example of a GIF image with more than one frame.

PNG

A PNG file, also known as a Portable Network Graphic is a type of bitmap graphic. The Portable Network Graphic has been created to replace the older file format the GIF (Graphic Interface Format). A PNG file does not require a patent license. This makes the PNG image better than a GIF image. A PNG file can support 24 bit red, green, blue (RGB), also 32 bit red, green, blue, alpha (RGBA) and greyscale images This type of file is widely used throughout the internet and with true colour natural images.

TIFF

A TIFF image is a bitmap based image format. The Abbreviation TIFF stands for Tagged Image File Format. The TIFF image is highly popular among people that use Mac as their operating system, graphic designers and the publishing industry. The Tagged Image File Format can be either a lossless or a lossy. Lossless and lossy are both different types of image compression. Most TIFF images use a lossless image storage meaning that the image will not be compressed at all. This makes TIFF files more unsuitable for use on websites due to the large file size. However digital cameras that use TIFF image format usually produce higher quality images in comparison to a digital camera that produce their images using other popular image formats such as JPEC images.

Vector File

A vector file is the other type of file format. Vector files are not made up of pixels like the bitmap file, instead they are made up of geometrical primitives, e.g. lines, curves, points and shapes. Therefore a vector file is a more mathematical equasion type of file format meaning that the equation will be altered so the image will always appear to be high quality and will not look pixileted . A vector file is made up of vectors. Vectors are also known as paths and stokes. These vectors can be filled with different colours, gradients and patterns. A vector file can be scaled up to five times its original size without reduction in image quality, this is an excellent advantage of a vector file. A few examples of vector file formats are .CDR, .AL, .GBM, .DXF and Gerber Format.

CDR

.CDR is a vector file format is a image extension that is used in the software coral draw. This software was invented by a software manufacturing company called Corel Co-operation. It is a 2 dimension vector file format which is a disadvantage.

AL

.AL is another vector file format that has been created by Adobe. It is the extension used that is used with the software Adobe Illustrator. A limitation of this file format is that it is only a two dimension image extension.

GBM

A .GBL file stands for Computer Graphics Metafile. It is used for two dimensional vector based images, raster graphics and text.

Gerber format

A Gerber format file, also known as RS-274 -X is a vector based image file extension that is used by Printed Circuit Board software and printers and by other companies that require high precision two dimensional bi-level Images. The Gerber format file was created by a company called Gerber Systems, however they have now changed their name to Ucamco.

SVG

A .SVG extension stands for Scaleable Vector Graphic. This is a very common type of vector image format and is widely used. It is used with vector graphic software such as Microsoft Visio, Corel Draw, Inkscape, Adobe Illustrator, GIMP and many other popular vector graphic creating software.

Benefits and limitation of graphical file formats

Bitmap

Benefits

Bitmap files are a lot more compatible with scanning technology in comparison to vector graphics.

A Bitmap image usually looks a lot more realistic and of high quality 

You have more choice in which file format you want to convert an image to, e.g. .JPEG, .GIF, .PNG, etc.

It is easier to print bitmap images onto material such as paper, cardboard, fabric, etc.

Limitations

A Bitmap file will loose image quality as it is scaled unlike a vector image.

Some bitmap files such as a  .TIFF, or a  .PSD file can be large in file size.

Vector

Benefits

A vector image is resolution independant and is based on points and mathematical equasions. This means that the image can me scaled without a loss in quality.

Shapes are easy to edit in a vector image

Vector images are very well suited for items such as sticksrs, t-shirts, logos, etc as they can be scaled to fit the item.

Limitations

Unlike a bitmap image, a vector image is incapable of reproducing a continuous tone photographic image.

Vector images tend to produce an unrealistic image and a more cartoon looking image.

Because a vector file has to load vector software and then open and calculate file paths it can be slow in opening therefore may be unsuited.

Image File Size

Below is seven images. All the images are the same, the only difference is that they are all in different image formats. I am doing this to display the difference in file size and in image quality.

Bitmap Image

Gif Image

Jpeg Image

PNG Image

TIFF Image

As you can see from the image below the bitmap image is clearly has the largest file size of 6751 KB. The second largest image is the PNG image, it has a file size of 4790KB. The TIFF image has a file size of 4345KB so a PNG and a TIFF image are around the same size. The two smallest file types are the GIF image and the JPEG image. The GIF image is the second smallest image. Its file size is 1031KB and the smallest file size is the JPEG image. It has an extremely small file size of 342KB making it very well suited for use on websites as the image will load faster.