3.5.6.4 Bitmapped graphics. Flashcards
Outline how bitmaps represent an image.
An image is broken down into pixels, each of which has a binary value assigned to it.
What do bitmap graphics represent?
An image.
Explain the following for bitmaps: resolution.
Resolution is expressed as number of dots per inch where a dot is a pixel.
What can resolution also refer to?
The number of pixels in an image.
Explain the following for bitmaps: colour depth
The number of bits assigned to a pixel in its image.
In an image, if each pixel had been assigned one bit then this would allow four 2 (2^1) different colours to be represented.
If a colour depth of two bits were used, there would be four (22) different
colours that each pixel could take, represented by the bit patterns 00, 01, 10 and 11
Colour depth = number of bits stored for each pixel.
What determines the colour of a pixel?
The value assigned to it.
Define a pixel.
The smallest addressable part of a bitmap image.
Explain the following for bitmaps: size in pixels
Size of an image in pixels is:
width of image in pixels x height of image in pixels.
Explain how to calculate storage requirements for bitmapped images.
Ignoring metadata,
storage requirements = size in pixels x colour depth
where size in pixels is:
width in pixels x height in
pixels
What must we be aware of when dealing with bitmap image files?
That they may contain metadata.
Outline the typical metadata for bitmapped images.
Width.
Height.
Data created.
Colour depth.
