The features and limitations of graphical files folder’s
Raster Graphics – A raster graphic is a file format that is used as a type of format for saving images/image files. It is the data structure that is used by images saved as this format and it is made up from and represented by a rectangular grid that can be made up from pixels or points of color and it is viewable on paper, on a monitor/computer screen or another form of graphic display medium.
Raster graphics correspond bit-for-bit with the image that is being displayed on screen and is mostly displayed in the same format that is used for its storage in the displays video memory, or as another independent bitmap. Raster graphics can be characterized by the width and height of the image in pixels and by the number of bits per pixel.
Advantages of Raster graphics
1. It displays true filled areas on the images and gives a realistic image
2. The images refresh rate is independent form the scene complexity is faster than some other file formats that are used and also the refresh hardware that is required is lower in cost than others.
Disadvantages of raster graphics
1. The size of a raster graphic cannot be scaled effectively as when you manipulate the size of the image it can become distorted and pixelated when the image is enlarge.
Vector graphics – A vector graphic is a digital image that is created and made up from colors which information is stored as a series of mathematical calculations and they are made up from paths and form these paths they make use of the mathematical relations between points and the paths that connect them to describe an image.
Advantages of Vector graphics
1. Vector graphics have the major advantage of being able to scale them to any size without any loss in image quality which is a major advantage for image editors.
2. Also another advantage of vector graphics is that they do not take up a lot of hard disk space so it saves memory on your computer
Disadvantages of Vector graphics
1. Vector graphics require your computer to work harder in order to display the particular image on screen and also because of this it may take longer for the image to be displayed on screen.
2. Vector graphics are not as good as other file formats for representing detailed graphics, so they cannot be used effectively to display photographs and other similar complicated images
J-Peg images – J-Peg stands for joint photographic experts group and it is a standardized image compression mechanism and it s designed for compressing either full colour or grey scale digital images of real world pictures/images.
Limitations - It works well on photographic images, artwork and other similar material but it does not work as well on things like lettering, black and white line drawings and simple cartoons.
Advantages – JPEG is a good format for producing photos, it can be used for the format of any photo that you have and/or want to submit and most in not all most all web browsers support the JPEG file format
Disadvantages – JPEG uses lossy compression algorithm so some of the images detail will be lost if/when it is changed to other file formats like a BMP to JPEG image but usually in the case of photos it is not noticeable. If an illustrated image or vector image is converted to JPEG it is possible for the edges of lines of the image to become blurred so it is advised to use a lossless compression format like the GIF format.
GIF images – GIF stand for Graphics interchange format and the image is in the bitmap format.
The GIF format has up to 8 bits per pixel in the image and this allows a single image to be able to reference up 256 distinct colours. The colours in the image are chosen form the 24-bit RGB colour space. The format supports animations and this allows the user to separate the palette of 256 colours in the image for each frame in the animation.
Limitations – A main limitation of the GIF format is that it is unsuitable for reproducing colour photograph images and other images with continuous colour because of the 256 colour limit however the GIF format works well with simpler images such as the creation of animation.
Advantages – GIF uses lossless compression algorithm when converting to other file formats this means that none of the detail of the original image is lost in this conversion. Images that use 256colours or less or grayscale images that are saved to the GIF format will not loose any detail in the conversion. GIF Images can have transparency and can be used in animation.
Disadvantage - The main disadvantages of the GIF format is that is has a 256 colour limit so if you are saving an image as a GIFF folder for example changing a picture from JPEG to GIFF there will be some of quality in the image.
JPEG Image
GIFF Image
TIFF images – TIFF stands for Tagged image file format and it is used mostly for the storing of images and it is popular among the users of Apple Macintosh users, graphic artists and the publishing industry. Tiff files are usually the best quality output form a digital camera.
Advantages of the TIFF format is that it is a flexible format that can use lossless or lossy file compression algorithm also the storage algorithm is included as part of the file.
Disadvantages of the TIFF format is that it is used almost exclusively as a lossless image storage format that uses almost no compression at all which is fine for image quality but not for file storage as the file sizes can be quite big.
PNG images – PNG stands for portable network graphics and it is an image that uses lossless data compression. The PNG was created in order to improve upon and replace the GIF file format as an image format that doesn’t require a patent license.
Features – PNG supports a palette – based images with the palettes of 24 bit RGB and/or 32 bit RGBA colours and grayscale images that do or don’t use the alpha channel .
Advantages – PNG does not require a patent license and supports 24bit RGB and/or 32 bit RGBA
Disadvantages – PNG was designed mainly for transferring images over the internet and not for printing images so it therefore does not support non RGB colour spaces such as CMKY.
BMP Images – A BMP images is sometimes referred to as a as a bitmap image or Device independent bitmap/ DIB and it is a format that is used for the storage of bitmap digital images mostly on the MS (Microsoft) Windows operating systems.
Image before change to bitmap
Image after change to bitmap
File Compression Techniques
File compression is when you take a data/image file and compress the size of that image so that it takes up less space on a computers hard drive when the image is save to it.
Lossy compression – When using lossy compression some of the quality/data of the file that you are compressing is lost as a result of saving it as a lossy file type however before saving it as a lossy file type it is assumed that you already know this and have taken it into consideration. In graphical images lossy compression some of the images resolution may be lost in order to create the smaller file size the loss may be may be in the form of the depth of the colour or the graphical detail of the image an example of this would be the high resolution details of an image can be lost if the image is displayed on a low resolution device.
Lossless compression – With lossless compression the data/image files size is compressed without any loss to the data/quality of the image yet the size of the file is still compressed in size.
Resolution and Colour depth
Resolution – Resolution is the term that we use to describe the dot or pixels used in the displaying of an image for example a high resolution images is created with more pixels so this results in the image looking crisper and cleaner.
A factor that can change an images resolution is the stretching of the width and height of that image, after stretching an image so much it is going to effect the quality of that image.
Before resolution change
Image after resolution changes
As you can see from the images above you can see that the quality of the image has pixilated with the changes that I have made to the size of the image, the image after the changes has lost a lot of its quality after the resolution changes.
Colour depth – The depth of colour displayed on images refers to how many bits of information that are being used to represent the colours of each of the pixels that are in the image so in general the more colours that are used in the images usually mean that better quality of that image but there are other factors that effect the quality of an image.
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