Understanding the features of image / audio files and formats can help you make appropriate choices to ensure that your use of image / audio is as successful as possible
What is your target? Know whether your image / audio file is going to be displayed
Which file format is best for a particular media?mp3, mov
How important is the quality of the image when transferred, copied, or displayed?
How important is the speed at which the image transfers or loads?
How important is the file size?
Saves space by discarding pixels not needed for viewing the file.
When opened the pixels are restored using colours from the available set
Data is lost every time a lossy file is edited and saved
In an image, it saves space by packing up and grouping common colours
no data lost when the file is opened and colours restored
e.g. 1. in one part of a picture it has many pixels the same colour. it is easy to compact that part of the picture to 239 pixels of green instead of repeating the pixel 239 times. This is how run-length encoding works (RLE)
e.g. 2. in an audio file there are parts the human ear cannot hear, so those parts can be removed making the file much smaller in size, but still lossless
the more pixels captured, the larger the file size
the more pixels captured, the larger the possible print size
less pixels cannot be made more, without losing quality
more pixels can be made less
how you are going to use an image = file size
minimum file size for 300 dpi at 100mmx150mm is 2 megapixels for quality prints
minimum file size for 300 dpi at 200mmx250mm is 5 megapixels for quality prints