1.2 Multimedia Flashcards
What is a bitmap image?
A digital image made up of pixels. Each pixel has one colour stored as a binary number.
What is the file header?
The file header holds data about the image.
1) Width + Height, measured in pixels
2) Type of encoding
3) Date stamp
What is the image resolution?
The amount of pixels an image contains per inch (dpi), determines the detail an image has.
What is the screen resolution?
Value quoted for monitor specification, eg 1024 x 768, the larger the number, the more picture elements displayed.
What is the colour depth?
The number of possible colours that can be used in an image.
What is the bit depth?
The number of bits used to encode a single pixel.
File size (in bytes)
(Width in pixels * Height in pixels * Bit depth) + Header bytes.
What impacts file size?
1) Image resolution
2) Colour depth
What impacts image quality?
1) Image resolution
2) Colour depth
What is a vector (SVG format) graphic?
An image made up of drawing objects. The properties of each object store a set of instructions that determine its shape and appearance, held in a drawing list.
Benefits of using a Bitmap.
- Bitmap images can be compressed, with a significant reduction in file size (vectors don’t compress well).
- Bitmap graphics use less processing power than vector graphics.
Benefits of using a vector graphic.
- Usually takes up less space than a Bitmap.
- Vectors can be enlarged without the image becoming pixelated.
What are Bitmaps suitable for?
Suitable for photographs / scanned images.
What are Vectors suitable for?
Suitable for geometric shapes, eg Flowchart diagrams.
How is sound encoded?
- Analogue sound wave picked up by microphone
- Sent to an Analog to Digital converter.
- Digitally stored as binary values.
