Raster and vector


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Raster and vector

  1. 1. Unit 65 Leeanne HibbertRaster and VectorA raster image is made up of thousands of little pixels which usually look like tiny squares, this willlook clear to you when you zoom into any raster image. Raster images are a way to represent digitalimages such as photographs and this is why they are ‘Bitmap’ based images as they are suitable forediting and editing programmes agree with raster images. Each raster image takes a variety ofdifferent formats like the familiar ‘GIF, JPG and BMP’.When a raster image is actually created the image on the screen that our eyes see as a digital imageis converted into pixels. Each and every single pixel that creates this image has its very own job andis signed on to a specific value which determines the colour. Any raster image will use the ‘RGB’system which means ‘red, green and blue’ and then an RGB value of the number ‘0.0.0’ is black. Allof the values go all the way through to 256 for every colour;this means there will be a wide range ofcolour values, for photographs with fine shading this can be very valuable.When you view a raster image the pixels normally smooth out visually for us meaning we cannot seethe pixels there. But as said previously as soon as you blow up/zoom the image the pixels becomevery visible to our eyes. Depending on the resolution of the raster image some can be enlarged toextremely large sizes while others can become difficult for us to see. The smaller resolution thesmaller the digital images file. Because of that reason people who work with computer graphicsmust find a balance between both image size and resolution.Raster based programme – PhotoshopPhotoshop is a programme where you can edit or create different graphics and this particularsoftware is raster based.So for instance this image above is the very recognisable ‘Ford’ logo, it does actually look like it wascreated in Photoshop but it is actually a vector image. Every single line of this is actually just a pointconnected with an angle of curve, vector. This means that you could scale this image as large as youwanted without losing any detail of the image. If a curve is closed (meaning both ends join) then youcan fill it with a colour.
  2. 2. Unit 65 Leeanne Hibbert This image below is the wireframe of a logo, which is followed by the same vector but now coloured in. Colour has just been added to this logoSo as you can see it is still alla vector image.You can seethe pixels (tinysquares) However this image above is a close up of a raster image and this is how graphics will look like in the programme Photoshop when you zoom into a certain graphic.So you will see an image like this as the entire image is made up of the tiny pixels (little squares). As said before a raster image is just made up of lots of pixels which will have a numerical value for each colour. People must remember that raster images cannot be scaled up in size because they will look very pixelated just like the image above, when they are printed. Other things you should know about Photoshop plus any other raster editing programmes are that they use vector images for the layout and elements such as text, but they are equipped to deal with the raster image basically down to the pixel and have special ways in doing so, such as the brightness/contrast or even adding lightening to the raster image in Photoshop. Photoshop and again other raster based applications are: . Touching up an image . Photo – realistic illustrations . Photo processing . Hand drawn illustrations .Collage The other editing programmes that are suitable for raster images other than Photoshop are: Adobe illustrator; Paint; MS paint and painter.
  3. 3. Unit 65 Leeanne HibbertRaster Image File formatsThese image file formats below are what raster images can be saved by.BMP – A BMP file format is a raster based file format and is also known as a bitmap and this is usedto store bitmap digital images.PNG- PNG stands for portable network graphic and this file extension uses index colours, this fileformat is basically for the portable, lossless and well compressed of the storage of raster basedimages.JPG/JPEG- JPG or JPEG stands for joint photographic experts group. This file format is mostcommonly used for publishing images to the World Wide Web and storing photographs.TIFF– the TIFF file format stands for tagged Image File Format. This is a high quality graphics formatwhich is often used for storing images with lots of colour like for instance digital images. These canbe saved in an uncompressed format which is lossless or may incorporate i.e. lossy compression.PSD – The PSD file format actually stands for an adobe Photoshop document and this means thatPSD can include editing images (so image adjustment) also layer masks and layers, plus fileinformation and other Photoshop elements.Gif – This stands for ‘ Graphical Interchange Format’ and this is the most common graphics formatthat is found on the internet. An ‘animated Gif’ is a GIF image that can be animated by combiningimages into a single GIF file.
  4. 4. Unit 65 Leeanne HibbertPaint VS PhotosopAs said above paint is also another raster based application and the reason why I am going to go intodetail about this particular programme is because it is on every single windows computer there is,you do not have to download it as it is already there for you. Paint is different to photo shop as it is avery simple graphics painting programme and just has the basic tools.This image above is what paint currently looks like. The programme saves the creation as a windowsbitmap so JPEG and GIF file formats (without animation or transparency). This programme can be incolour mode or black and white, but unlike photo shop there is no grayscale mode.Photoshop is a lot more powerful than paint as there are lots of features o Photoshop that are notincluded on paint. For example paint doesn’t have a tool used to replace part of a picture that youdon’t want and remove it by replacing with its background. So Photoshop has a lot more options forediting images than the programme paint. The difference between these two programmes is thatpaint is a very simple drawing programme while Photoshop on the other hand is one of the mostpowerful drawing and editing programme there is.
  5. 5. Unit 65 Leeanne HibbertVector ImagesA vector image is a format that your computer uses to actually create an image. These are acollection of individual objects; unlike a raster image which is more of a picture element. Vectorimages are connected by curves or shapes; this is unlike raster based images as raster images arecreated by pixels. Curves and shapes of a vector based image are ok to edit such as the colour;outline and fill of it. Vector images are made up of mathematical equations so they are alwayscreated at the highest of quality.Changing around of a vector image will not affect the object itself as you can change any number ofattributes freely without destroying the basic object. Vector images are processed on softwareprogrammes such as: ‘Adobe illustrator’ or ‘CorelDraw’. Vector images can also be converted into araster image by using a raster to vector conversion programme like ‘CorelTRACE’ and ‘Euro VECTOR’.As I said previously adobe illustrator is a vector based programme and this approaches image
  6. 6. Unit 65 Leeanne Hibbertcreation in an entirely different way and do not render images on a pixel by pixel basis.This image above as you can see is just made up of lines and dots, one on every corner. These areknown as ‘vector points’ and these allow the computer to connect the dots. Each vector point hasinformation that tells the computer how to connect each point with straight or curved lines, plusknowing what colour the inner space should beBecause the computer only has to keep four points in its memory, it is much easier for the computerto edit vector based images as file sizes are really small. If you resize a vector based image it loseslittle or no detail at all, the vector points spread out and the computer just redraws the image.Vector images are ideal for logos as they can beresized and adjusted without losing clarity, so whenlooking for a logo designer ensure the final filesproduced are vector based.Adobe IllustratorAdobe illustrator programme is probably one of thebest applications there is for creating a vector based graphic. I myself have personally used thissoftware to create my very own graphic and the best part about it was that I could save my imageand it did not use any detail what so ever which is different to raster images as If I had created araster image and resized it then once I save it, then it will probably lose quite a lot of quality.The vector graphic I created was a pencil and pencil pot as you can see on the right hand side of thispage. The only problem with illustrator and vector based images is that they do look quite like clipart instead.As you can see by my own image vector image it is just literally made up of lines; curves anddifferent shapes. This is why you lose no quality what so ever when it comes to saving as it has nopixels that are the creation of the image to a raster.
  7. 7. Unit 65 Leeanne HibbertMetafiles (WMF)Metafile is a term for a file format that can store multiple types of data. Metafiles commonly includegraphic file formats and these graphics can contain both vector and raster based. It can also combineraster and vector based images together such as the outline being the vector and the fill of theimage being a bitmap. Also Microsoft windows uses ‘windows metafile’ and this was originallydesigned for Microsoft windows in the 1990s and does in some ways act very similar to the SVG files.Windows metafiles may contain both vector graphics and bitmap components. A WMF file actuallystores a list of different function calls that have to be issued and approved by windows ‘graphicdevice interface’ also known as GDI.Vector Image File FormatsEPS– The EPS file format stands for ‘Encapsulated Post Script’, the word ‘post Script’ is used todescribe how the images are exported to desktop publishing programmes such as Postscript Printeror Microsoft Publisher. EPS files can mix pixel based images with Vector images into one file,however file sizes can be large so you do need a programme like ‘Postscript printer’ to print theseimages out.AI – The AI file format stands for Adobe illustrator which is the most popular programme for creatingvector images on. This programme is a ‘charter’ programme and deals with objects such as circles,squares and many other irregular shapes. These objects can be re-sized, re-coloured and moved.These shapes once made or edited can be stored into files as ‘geometric equations’ with a certaincolour value, size and location.FLA – The FLA file format stands for flash animation and is a 2D animation programme that is used tocreate vector based websites and create animation. The files are rather small compared to other
  8. 8. Unit 65 Leeanne Hibbertweb design programmes like ‘Adobe Dreamweaver’; this is because it is a vector based programme.The FLA file has advantages as it leads to much shorter download times when you are surfing theinternet.