Thursday 3 March 2016

Print size PPI and DPI

Print size PPI and DPI



Resolution refers to the number of pixels in an image.
Resolution is identified by the width and height of the image as well as the total number of pixels in the image.
PPI: Pixels per inch.
Most commonly used to describe the pixel density of a screen (computer monitor, smart phone, etc…) but can also refer to the pixel density of a digital image.
DPI: Dot’s per inch.
The number of dots in a printed inch.
The more dot’s the higher the quality of the print (more sharpness and detail).
 
The basic equation for calculating PPI is:
PPI = height(pixels)/ height of image (inches).
So, for example, if you want to print a 4-inch-by-6-inch image, and your pixel count is 800 x 1200, you need to divide 800 (the pixel height) by 4 (the photo height) and then divide 1200 (the pixel width) by 6 (the photo width).
 
The PPI will be 200, providing you with good quality photos.
However, if you want to print a larger photo, for example 8-inch-by-10-inch photo, the PPI reduces to 100 for width and 120 for height, giving you lower quality prints

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