Storing Images Flashcards
What are the images called mainly used for photos?
Bitmap images, they’re made up of loads of little dots called pixels.
What is each colour of a pixel represented by?
Binary code. The number of colours available is related to the number of bits the code has.
What bits do black and white images need?
They only use two colours so only need 1-bit to represent each pixel.
- 0 for white
- 1 for black
What are 2-bit images made of?
Four colours. Each pixel can be made up of four binary values: 00, 01, 10 and 11
How can you make a greater range of shades and colours in an image?
Increasing the number of bits for each pixel.
What is the colour depth?
The number of bits used for each pixel.
How can you work out how many colours can be made if you know the colour depth?
total number of colours = 2^n
where n = number of bits per pixel, or bpp or colour depth
What colour depth do most devices use?
24-bit, with 8 bits used to indicate the levels of red, green and blue needed for each pixel. It’s estimated the human eye can see around 10 million different colour, so the 24-bit colour depth should cover every possible colour we could see.
What is resolution?
The density of pixels in an image. i.e. how many pixels there are within a certain area.
What is resolution normally measured in?
Dots per inch (dpi)
How does it affect the image the higher the resolution?
The more pixels in a certain area so better quality of image.
Having more bits in an image due to increasing resolution means what?
It improves the image quality but increases the file size.
What is metadata?
The information stored in an image file which helps the computer recreate the image on the creek from the binary data in each pixel.
What does metadata usually include?
The image's: - file format - height - width - colour depth - resolution also extra things like: - time and date the image was created or last edited
Without metadata what would devices not be able to do?
Display the image on screen as intended.
