It is not necessary for people to be technically minded in order to understand the basics of DPI, PPI & Resolution. These terms can look confusing at first glance, but they actually refer to something that is relatively easy to understand. The benefits of learning a bit about resolution is that it means that the individual will be better able to make decisions when dealing with all types of graphic image.
The easiest way to explain resolution would be to say that it refers to the number of small squares of colour in a picture. These squares are generally referred to as pixels, and they are combined in such a way as to create the desired image. When people say that an image has a high resolution, they are really saying that is has a high number of pixels. By increasing the number of pixels used to create an image, it causes this image to appear smoother and more realistic – generally speaking.
Pixels or Dots
Pixels will sometimes be referred to as dots, but this can be confusing because it gives people the impression that pixels are round with empty spaces between them because of this shape. Pixels are always square, and there are no spaces between them in an image.
DPI
Dots per Inch (DPI)is a term used to describe the number of printer dots that appear on paper when printing off an image. It is actually referring to the number of droplets of ink that will be laid down on the paper. DPI indicates the number of dots that will be in the span of one inch. The higher the DPI, the more ink droplets will be used print off the image. A high DPI does not necessarily mean a clearer image because too much ink can impair shadow detail and lead to a less than ideal print.
PPI
Pixels per Inch (PPI)refer to the number of pixels in the span of one inch. A pixel (picture element) can be described as the smallest possible area of illumination on a computer screen. Each pixel is made up of three colour dots – red, blue, and green – and it is possible to change the brightness of each dot to create millions of possible colours. If the PPI is low, it leads to images that look jagged. Professional photographers will usually want to save images that are at least 300 PPI.
Importance of PPI
The reason for why it can be so important to know the PPI is because this will determine the maximum size of the image that can be created without a noticeable decline in quality. This is because the amount of information available in the pixel cannot be increased afterwards, and if the image is too big the individual pixels will be larger thus reducing the overall crispness and quality.
Difference between DPI and PPI
DPI and PPI are different ways of measuring resolution – one is a measurement of dots on paper, and the other is a measure of pixels on a screen. It is easy for people to get mixed up between dots and pixels, but they are not the same thing. DPI is used to help people determine the resolution of their printer and PPI is the resolution of their image on their screen. Even the experts will tend to get these to measurements confused, but it can be important to understand the difference between the two.
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Robert Petterson is a blogger at www.document-options.co.uk a Brighton printing company. Robert enjoys sports and technical drawing in his spare time and perfecting techniques for the copyshop in Brighton.
