Images Flashcards
What are the 2 most popular types of input devices for creating an image in binary form?
Flatbed scanner
Digital camera
How does a digital camera work?
It has an image sensor that creates binary files directly.
These files are then stored in the camera’s memory card or transferred by USB cable and Wi-Fi into a computer
What are pixels?
One of the individual units (often called dots) that make up an image
What does increasing the number of pixels do?
Makes the image looks completely smooth (higher resolution)
How does a bitmap image file represent an image?
As a series of pixels
What is a popular bitmap image file format?
BMP (Device Independent Bitmap File)
Why can BMP files be large and take up a lot of storage?
It has data on every single pixel
What word can be used to describe a BMP file?
Uncompressed, as it has data on every single pixel
How are JPEG files compressed?
Lossy Compression - Some non-vital pixel information is discarded. So although some quality is lost
What is a megapixel equal to?
A unit of resolution equal to one million pixels
What can a binary number represent?
A single, specific colour
What do you need to display greater range of colours?
A greater range of binary numbers
How many colours will 2 binary numbers represent?
2 - black and white
What is a greyscale image?
An image containing only different shades of grey
What three colours can the cells in our eye pick up?
Red
Green
Blue
How much memory is assigned to each pixel?
1 byte of memory for each of those three values (RGB)
How many different shades of red could be displayed with a 1 byte pixel?
256
How many possible colours could be displayed with a 3 byte number system?
256x256x256 = 16.8 million
What is colour depth?
The number of bits per pixel used to represent a colour
What does a greater colour depth mean?
The better the colour rendering
What happens to the file size with a greater colour depth?
A larger file size because it is storing more bits per pixel
What is colour depth measured in?
Bits per pixel
What is image resolution?
The number of pixels per inch
What does a higher number of pixels cause?
A greater resolution
What is resolution measured in?
Dots per inch (dpi)
What does a high resolution mean for an image?
A greater amount of detail can be seen
What happens to the file size with a greater resolution?
The file size gets larger because more information needs to be stored about the image
What is metadata?
Extra information stored in the image file to help render it properly
What are digital images stored as?
Data files
What 6 things does metadata include?
Width in pixels Height in pixels Horizontal resolution in dpi Vertical resolution in dpi Colour (bit) depth Dimensions
What does metadata help an application to do?
Render an image properly
