Wednesday, February 29, 2012

Document Size increases on changing from Higher PPI to Lower PPI || What exactly is PPI - Pixels Per Inch in a Photograph

First of all, Let's understand what PPI is ? PPI stands for 'Pixels per Inch', which has literal meaning that when a image is constructed, how many pixels are places in one inch region of that photograph. More the pixels, better is quality and increase the chances of using this image for various purposes. This is one of the reason that many times people reduce the PPI for a photograph before posting on websites or blogs, so that others can't use them for any commercial purpose. Let's continue this discussion from here...

PPI stands for 'Pixel Per Inch' and at times, DPI is also used in different context. DPI stands for Dots per inch. But for now, let's refarin from confusing between these two terms and focus on term PPI which is most of the times discussed when we talk about printing technologies for images. Many Digital Imaging softwares use PPI in various workflows.

What effectively means when we say 300 PPI? We have a photograph which has 300 pixels in each inch and 100 PPI means 100 pixel in every inch of a photograph.

Now let's take an example of Nikon's Full Frame D700 Camera which produces an image of 4256 by 2832. So if we set 300PPI, we will get a photograph which will have following dimensions -

Height - 2832/300 = 9.44 inches
Width - 4256/300 = 14.18 inches

And if we set the same image at 100PPI we will get following dimensions -

Height - 2832/100 = 28.32 inches

Width - 4256/100 = 42.56 inches

Which means increasing PPI means, decreasing size of photographs and many folks think it otherwise !!!

Please comment back in case you like it or have more queries about it.

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