[Frameworks] DPI

[Buck Bito - Movette]

Hi Gene,
The dimensions you quoted look like pixel dimensions.
DPI is a term from the printing industry that refers to a physical
manifestation (dots per inch). It doesn't really apply to digital
manifestations of an image. The corresponding digital term would be ppi
(pixels per inch) which is an attribute of a display device rather than a
file - although files can have a specified ppi, in practice unless we are
creating a physical manifestation, it has little meaning.

So in the purely digital realm, if left unscaled, that 400x500 image file
will have very different sizes depending on the ppi of the display device:

The the LCD on the laptop I'm typing on has 107ppi: 3.74" x 4.67"
iPhone6 (326ppi): 1.23" x 1.53"
iPhone6plus (401ppi): 1" x 1.25"
A 60" 1080p TV (37 ppi): 10.81" x 13.51"

The little iPhone6plus has the same number of pixels as a gigantic 60"
1080p HDTV, so that 400x500 image will be 1 inch wide on the phone and
almost 11 inches wide on the TV.

-Hope that helps,
--Buck Bito

Lawrence "Buck" Bito
Movette Film Transfer
1407 Valencia St.
San Francisco, CA 94110
(Valencia at 25th St.)
415-558-8815
Open Tuesday - Saturday
Tue+Thu: 8-6, Wed+Fri: 9-6, Sat: 10-4
www.movettefilm.com

On Wed, July 1, 2015 10:24 am, Gene Youngblood wrote:
> Friends, am I assuming correctly that when you "get info" about the
> properties of an online photo, "dimensions" (i.e., 400 x 500) refers
> to DPI?
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