Introduction to Resolution
Resolution is something of prime importance in digital arts. In a general term it is referred to image resolution, monitor resolution and output device resolution. To be precise, it is a unit of measurement, used to determine the size of an image, the way an image displayed on the monitor and the device on which an image is output.
While preparing the image in digital arts we have to consider these three ways of resolution. Different Raster packages, like Photoshop etc. comes up with different facilities to decide and manipulate resolution.
It is essential to have good amount of knowledge of this resolution concept as it affects the entire artwork. With web, it can totally change the appearance of the design of the site. Specially, it is considered to be the job of skilled person when it comes to resolution while scanning.
It is measured in ppi i.e. pixel per inch. It can be defined as number of pixels in the image. The more the pixel in the image the higher is the resolution and larger is the size of the file. It can be explained with the following example. A 1-inch square of an image scanned at 72 ppi contains 5184 pixels (72 X 72) and has a file size of 6K, if the same file is scanned at 144 ppi will contain 20736 pixels (144 X 144) will have file size 21 K.
It's a hardware related resolution hence it is fixed, decided by the manufacturer of the monitor. It is measured in dpi (dots per inch). Mostly monitors come with 72 dpi resolution. It determines how your image is displayed on your monitor. Image with higher resolution appears larger on the screen. An image scanned at 144 ppi appears doubled then the image scanned at 72 ppi because on 72 dpi monitor, only 72 of the 144 ppi can be displayed in one inch. Check out the tutorial where this concept is explained using example.
It is measured in dpi (dots per inch) and lpi (line per inch). It is device dependent. It determines the quality of the final printed image. Normal inkjet printer can have the resolution of 300- 600 dpi where laser may go up to 1200 -2400 dpi or even higher.
Each pixel has particular depth which is called as "Bit Resolution". It measures the amount of color information stored per pixel. This is again measures in number of bits.