Image Representation Flashcards
1
Q
How are bitmap images stored in memory?
A
- The colour value of each pixel is stored consecutively within VRAM
- Each pixel is MAPPED to one or more addresses
- The video systems read the values from the data buses
2
Q
What are bitmap graphics made of?
A
- Image is broken down into pixels
- Binary values of pixels determine the colour
3
Q
How to find the resolution of an image? How to find image size?
A
- Resolution is the number of dots per square inch (dot is pixel)
- Image size = image height x width
4
Q
What is colour depth / bit depth?
A
- number of colours in image = 2^n
- n is the colour depth
- this is the number of bits required to represent the different colours
5
Q
How do you calculate file size for bitmap images?
A
- file size = bit depth x image size
- this file size is in bits
6
Q
What is in the header for bitmap files?
A
- metadata (info about image) : GPS, camera, time and date
- colour depth
- resolution
- THIS INFO IS NEEDED TO DECODE IMAGE
7
Q
What are vector images?
A
- images are represented as geometric objects and shapes
- their properties such as fill colour, fill style and dimensions stored in a list
8
Q
Why are vector graphics used as compared to to bitmapped graphics?
A
- infinitely scalable without losing quality
- easily manipulated or editable
- small file sizes
- suitable for icons, logos but not photos
9
Q
What are the disadvantages of vector images?
A
- cannot produce photo-realistic images
- can take longer to render a complex image
- cannot use if colour is likely to vary from pixel to pixel
10
Q
What is a pixel?
A
the smallest addressable element of an image
