Representing an image as a series of pixels questions and answers
Q1. Define ‘pixel’.
A1. A single dot of an image.
Q2. When talking about pictures, what is meant by a ‘bitmap’?
A2. The collection of information stored in pixels that describe a picture.
Q3. What is a ‘codec’?
A3. A maths formula, which when applied to a file, compresses it.
Q4. State three types of picture codec.
A4. E.g. JPG, GIF, TIFF.
Q5. How many colours are used in a GIF picture compared to a JPG picture and select a typical use for each type of picture.
A5. GIF = 256 colours, JPG = approx. 65000 colours. GIF ideal for icons, simple drawings, JPG ideal for photos and other pictures, which require many shades of colour.
Q6. What type of picture file does a scanner take?
A6. They take bitmaps. Typically, you would specify in the scanner's settings what codec to convert the picture into.
Q7. What is meant by 'resolution'?
A7. This is the term used to describe the density of pixels in an area.
Q8. What is the colour depth of a picture?
A8. The colour depth is the number of bits you are using to record details about the colour of each pixel.
Q9. How do vector images differ to bitmaps?
A9. Vectors use formulas to record pictures rather than details about each pixel used.
Q10. Name one drawing application that is free to download, great fun and uses vector rather than bitmap images?
A10. SketchUp!