How does LifeSizer actually work?

In the online community there is a long standing joke about the “online ruler problem”.  How can it be that we can solve incredibly complex technical problems that allow sites to scale to millions of users across the globe, but we can’t show a ruler in actual size on a screen.  Well, we’re happy to say that LifeSizer has finally solved this problem!

LifeSizer allows sites to display images or products (including an online ruler) in actual life size by determining and reconciling the physical dimension data and digital resolution data of two different elements:

  1. The physical dimension of an object within an image.  This is determined by using your mouse to draw an arrow on the product in the image (e.g., along the length or width) and indicating how long the arrow is.  This is used in conjunction with the digital resolution data inherent in all digital pictures (e.g., 200 pixels wide by 300 pixels tall) to then calculate the actual life size pixels per inch for that image.
  2. The physical dimensions of the screen on which the image will be displayed.  This is determined automatically for some mobile devices and Mac computers but for most computers this requires input from the user.  However, most users don’t know the physical dimensions of their screen (e.g., 13.3” inches diagonal) so LifeSizer uses a simple methodology that allows users to determine their physical display dimensions using nothing more than a commonly available real-world item (e.g. a CD/DVD, ruler, dollar bill, credit card, etc.).  By zooming in or out on an image of a CD on the screen until it is the same size as the one they are holding up to their screen, we can determine the Pixels Per Inch of their display.  This PPI is then used in conjunction with the digital resolution data available inherent in all computer screens (e.g., 1920 pixels wide by 1080 pixels tall) to then calculate the actual life size dimensions for that display (e.g., X inches wide by Y inches tall.

With these two data points (pixels per physical inch of an image and PPI of a screen) LifeSizer is able to scale the image to display a product in its actual life size.

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