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Crossing the Boundary

Crossing the Boundary. Images. Vision is far and away humankind’s most dominant sense. Every sighted person lives their entire waking (and dreaming) life at the centre of a visual field, a sphere of light, shade, colour, form and movement. Let’s try a simple example. COLOUR.

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Crossing the Boundary

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  1. Crossing the Boundary Images

  2. Vision is far and away humankind’s most dominant sense. Every sighted person lives their entire waking (and dreaming) life at the centre of a visual field, a sphere of light, shade, colour, form and movement.

  3. Let’s try a simple example.

  4. COLOUR 1. How is it possible to map a particular colour to a number? 2. How many colours do we want?

  5. Question The image of Mordor at the start of this presentation contains 647 6 735 pixels, with the full 16 million colour palette. Work out how many bits are required to store this image as a bitmap inside the computer. How many bytes? Discussion The image has 647 6 735 = 475,545 pixels. Each pixel will require 24 bits – that is, 3 bytes. So the image will require 11,413,080 bits, or 1,426,635 bytes which is nearly 1.5MB.

  6. Question Why do you think storing such a diagram as a bitmap would be a waste of memory? Answer The huge majority of the pixels will just be white, the background to the picture. The only information all these white pixels give us is the simple fact that the background colour is white.

  7. Cartesian coordinates

  8. Vector Graphics / Raster Graphics • Advantage of the vector strategy is that it is a very compact form of coding. With just 41 numbers (about 984 bytes), we have summed up the essence of our diagram. A bitmap of the same diagram would have required at least tens of thousands of bytes. • Another advantage of vector graphics is the resulting image is scalable: we can easily shrink or stretch the size of it without any loss of information. • Problems. First, vector coding only really works with fairly simple images. It would be hopeless for the Mordorpainting. Second, if I send the set of numbers we generated to a friend, they will need a sophisticated computer program on their computer to interpret the numbers and display them as a diagram. • Drawing Packages – Painting Packages

  9. Image for exam question

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