Unit 30 D2

D2 Describe and evaluate the impact that file format, compression techniques, image resolution and colour depth have on file size and image quality. File format .jpg images are compressed and the compression often leaves visible signs of compression, which is normally a blocky or speckled appearance. .gif images can only display up to 256 colours, so this means that the quality of the image may be affected. .png images are compressed too but they normally use "lossless compression" so the visual quality can be pretty high. .bmp images are not compressed. They are the best quality file, but also the largest of all files. Image Resolution The image resolution is the pixels. If you have two pictures of the same thing but one is 1024x768 and the other is 640x480, the first will be crisper because it has more pixels per square inch. The more little blocks of colour you can fit into a smaller space, the better quality the image will be. Compression Techniques Graphic file compressors take away pixels, and if you take away too many of them, then the quality of your image is reduced. If one goes too far in the compression, then the picture becomes unrecognizable or is so pixelated it won’t be of any use. Some graphic compressors will give you the option on the compression before you save it to a new file. Colour Depth This is the amount of Bits in an image, colour depth is made from the number of bits in each pixel. Depending on how many bits there is in a pixel, results in the difference of colour depth in certain bits per pixel (bpp), so more shades of a colour can be displayed on the screen. This makes the image look sharper and a better quality than images with less bits per pixel.

Unit 30 D1

D1 Printers: The older printers where all quite basic, and they all had many limitations such as printing speed. But now they come with things such as scanners attached to them and you can connect your digital camera to them to print straight from the camera instead of going through the computer. - has to be high resolution so that they dont An inkjet printer is used mainly for the printing of posters. It creates a digital image by propelling droplets of ink onto paper, plastic, or other substrates. Inkjet printers are the most used type of printer, and they have a wide price range from small inexpensive ones for everyday use to large professional machines that cost thousands of pounds. A laser printer is an electrostatic* digital printer that produces high quality text and graphics by passing a laser beam over a charged drum to define a differently charged image. 3D printing is a process where a three dimensional solid object of nearly any shape is made using a digital image. This is achieved through using the ‘additive process’ where many different layers are laid down in different shapes. 3D printers uses STL files that is used for stereolithography CAD (the printing of 3D models) which is the software that is needed for the 3D printing process. Cutters: Vinyl and laser cutters are used for making signs and can create very big and detailed images. They are normally used by businesses to put onto buildings or vehicles. Using the cutters to make the designs for a business makes it more personal and will also decrease the amount the creation will cost. In 1965, the first production laser cutting machine was used to drill holes in diamond dies (which is a tool used to cut specific shapes.) It was used by the Western Electric Engineering Research Centre. In 1967, the British pioneered laser-assisted oxygen jet cutting for metals. In the early 1970s, this technology was put into production to cut titanium for aerospace applications. At the same time CO2 lasers were used to cut things that weren't metals, such as fabrics. A vinyl cutter is a computer controlled machine that cuts vinyl shapes out. Smaller vinyl cutters look like computer printers. Vector images that have been made on the computer like shapes and letters can be directly cut onto the vinyl. Vinyl cutters are more commonly used to make signs, banners and advertisements.- needs to be a vector

Unit 30 M2 edited