Learning objective
Bitmapped graphics: Explain how bitmaps are represented. Explain the following for bitmaps: • resolution • colour depth • size in pixels. The size of an image is also alternatively sometimes described as the resolution of an image. Size of an image in pixels is width of image in pixels x height of image in pixels. Resolution is expressed as number of dots per inch where a dot is a pixel. Colour depth = number of bits stored for each pixel. Calculate storage requirements for bitmapped images and be aware that bitmap image files may also contain metadata. Ignoring metadata, storage requirements = size in pixels x colour depth where size in pixels is width in pixels x height in pixels. Be familiar with typical metadata. eg width, height, colour depth.
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Topic
Representing images, sound and other data
Subtopic
Bitmapped graphics
Aqa A Level Computer ScienceFundamentals of data representation
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Quick explanation
Bitmapped graphics: Explain how bitmaps are represented. Explain the following for bitmaps: • resolution • colour depth • size in pixels. The size of an image is also alternatively sometimes described as the resolution of an image. Size of an image in pixels is width of image in pixels x height of image in pixels. Resolution is expressed as number of dots per inch where a dot is a pixel. Colour depth = number of bits stored for each pixel. Calculate storage requirements for bitmapped images and be aware that bitmap image files may also contain metadata. Ignoring metadata, storage requirements = size in pixels x colour depth where size in pixels is width in pixels x height in pixels. Be familiar with typical metadata. eg width, height, colour depth
- This point belongs to Representing images, sound and other data, especially Bitmapped graphics.
- You need to be able to bitmapped graphics: Explain how bitmaps are represented. Explain the following for bitmaps: • resolution • colour depth • size in pixels. The size of an image is also alternatively sometimes described as the resolution of an image. Size of an image in pixels is width of image in pixels x height of image in pixels. Resolution is expressed as number of dots per inch where a dot is a pixel. Colour depth = number of bits stored for each pixel. Calculate storage requirements for bitmapped images and be aware that bitmap image files may also contain metadata. Ignoring metadata, storage requirements = size in pixels x colour depth where size in pixels is width in pixels x height in pixels. Be familiar with typical metadata. eg width, height, colour depth.
- Use the linked flashcards and practice questions to check recall, then practise applying the idea in an exam-style answer.
Why it matters
This objective helps connect Bitmapped graphics to exam-style questions, flashcards, and revision notes for Representing images, sound and other data.
Quick student answer
What is meant by the colour depth of a bitmap?
Direct answer
The number of bits stored for each pixel
Key terms
- Bitmap: An image represented using pixels, with bits stored to describe each pixel.
- Metadata: Information stored in an image file about the image, such as its width, height and colour depth.
Common trap
Confusing resolution with size in pixels: Width × height gives the size of the image in pixels. Resolution is expressed as dots per inch, where a dot is a pixel.
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