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20 Cards in this Set
- Front
- Back
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Define Pixel |
Pixel is smallest block of colour in an image |
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What is a Bitmap? |
Bitmap - is created when the pixels of an image are mapped in position to memory that store binary codes representing the colour of each pixel |
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What does 1024 x 768 mean? |
- 1024 x 768 means there are 1024 pixels wide and 768 pixel high |
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Define Resolution? |
Resolution - the number of pixels per unit inch - the higher higher per unit inch - the higher the resolution |
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What is Colour depth? |
Colour depth - is the number of bits used to represent one pixel
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If the colour depth is n what is the number of colours available? |
if the colour depth is n- the number of colours available are 2^n. |
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What is 1-bit colour? |
1-bit colour is black and white |
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What is 12-bit direct colour and where is it used ? |
-12-bit direct colour - 2^12 different colours - used in displays with limited size like mobile phones |
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What is 24-bit true colour? |
24-bit true colour - 2^24 colours |
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What is 32-bit colour ? |
32-bit colour - 2^32 colours |
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How do you work out the number of bytes in a bitmap? |
To work out the number of bytes in a bitmap - - Multiply the number of pixel wide by the number of pixel high - Multiply that number by the colour depth - Divide the answer by 8 to get from bits to bytes |
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What happens when a bitmap image becomes scaled? |
When a bitmap image becomes scaled - it becomes distorted because the size of the pixels increases which means the resolution decreases because there will be less pixels per unit inch. |
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What is Vector Graphic? |
Vector graphic - an image that is created by formulae and not made by pixels |
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What are the advantages of vector graphics? |
Advantages of vector graphics: - They are not distorted when they are scaled because they are intrinsically resolution free - if the image involves shapes - it will store less memory than if it is stored as a bitmap - it is easy to manipulate the shapes that make up the vector graphic compared to manipulating direct areas from a bitmap |
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What is an object? |
Object - an object of a vector graphic like circle, triangle , square. |
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What is a Property ? |
Property - property of an object of a vector graphic like size, direction, thickness colour
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What is Drawing list? |
Drawing list - list of drawing commands that are needed to create a vector graphic |
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What is the advantage of a bitmapped graphic? |
Advantage of bitmapped graphic is that if the image includes continuous areas of colour - the image will store less memory as a bitmap than if it stored as a vector graphic |
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What is Data compression? |
Data compression - squeezing the data so that is stored with less byte than it was before
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What is Lossy compression |
Loss compression - the image is different after compression than it was before compression. For images - lossy compression would involve doing something that is not very important for the image like reducing the resolution of the background |
