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Web Design week 4 (Colour (Colour Depth (The amount of memory that is…
Web Design week 4
Colour
Colour Depth
The amount of memory that is required to store a bitmap depends upon the number of pixels and colours in the bitmap.
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Dithering is the process of placing pixels of two different colours adjacent to each other to simulate a third colour.
Colour models
Different models are used to represent colour on a computer. The three models are: RGB colour, CMYK colour and indexed colour.
The RGB model expresses the colour of a pixel as an amount of red, green and blue⎯an RGB value. The abbreviation RGB comes from the names of these three colours.
The CMYK model expresses the colour of a pixel as an amount of cyan, magenta, yellow and black⎯a CMYK value. The abbreviation CMYK comes from the names of these four colours. Black is represented by the letter K because in printing jargon, the plate that is usually impressed with black ink is called the key plate. The CMYK colour model is commonly used to prepare full-colour work for printing
The indexed colour model is suitable for images with 256 or fewer colours. These images have a colour palette (also known as a colour lookup table) that specifies which 256 colours out of the millions possible are available. Each colour in the palette is assigned a number between 0 and 255. The image refers to each colour by its position in the palette.
Colour schemes pp 12-17
Choosing the right colours for a design is both a subjective and technical exercise, complicated by diverse factors such as the way people react to colour and the nature of colour vision. Artists, printers and colour theorists have historically based their ideas about colour on the 12-step Red Yellow Blue (RYB) colour wheel shown in Figure 4-15.
Acquiring image
How do you acquire images for a website? If you have access to a camera or a scanner, the simplest option might be to produce your own. Sometimes, however, it is necessary to use existing images. This section discusses a variety of image sources.
Royalty-free images:
Royalty-free images, supplied by companies such as Getty Images (https://www.gettyimages.com.au), Shutterstock (https://www.shutterstock.com) and iStockphoto (https://www.istockphoto.com/au), take much of the hard work out of image acquisition. The term royalty-free means that once you have paid the licensing fee for an image, you have unlimited use of it for most purposes. Not surprisingly, license agreements for royalty-free images usually contain restrictions preventing you from sublicensing or reselling the images separately or detached from a product.
Taking your own images
If you have to create your own images from scratch for a website, there is a good chance that you will need to use a digital camera at some point. While this isn't a photography unit, it would be useful to consider some suggestions for effective composition (Olympus 1992).
Bitmaps Images
A bitmap is an image that has a dot pattern stored in the image. The things you can do are, create an image using an image software system, capture an image from an active computer screen, scan a photographic print or some other hardcopy image with a scanner, capture a frame from a source with a video capturing device or take a picture with a digital camera.
Vector Images
A vector image is a collection of lines, rectangles, circles, polygons and other geometric shapes that can be defined mathematically. Vector images can be created with a drawing program such as Adobe Illustrator.
Scanning
Scanners turn photographic prints and other hard copy into image files that can be manipulated with image-editing software such as Photoshop. When you scan a photograph, the scanning software might prompt you to specify the following details for the resulting image.
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