RPi Camera Module DPI


4 posts
by prevoste » Wed Jul 24, 2013 3:02 pm
Hi All,

I notice that taking an image using the default settings with raspistill produces an image of size 2592 x 1944 with a dpi of 72. Taking a picture with an old 6mp digital camera produces an image size of 2816 x 2112 with a dpi of 180. I don’t fully understand the relationship between the image size and dpi. Is it possible to get the Camera module to increase the dpi?

Ernie
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by towolf » Wed Jul 24, 2013 3:07 pm
DPI means nothing. It would only give your paper printing programme a hint of how big you want the image printed on a sheet of paper. It's just a scale factor. Attaching a dpi to a photo is arbitrary. 72 dpi is commonly used as shorthand for "screen resolution"

The only thing that counts is total number of pixels i.e., image dimensions. Unfortunately, less than knowledgeable people in the past equated resolution with dimension and the word resolution lost its meaning. Resolution is detail per area.
Last edited by towolf on Wed Jul 24, 2013 3:39 pm, edited 1 time in total.
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by jamesh » Wed Jul 24, 2013 3:37 pm
If necessary you shoudl be able to change the DPI value in the EXIF using the -exif command line option. I've never tried to though.
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by prevoste » Wed Jul 24, 2013 4:15 pm
Thanks to Towolf & Jamesh for your quick replies.

I have a better understanding now.


Ernie
Posts: 26
Joined: Mon Jul 16, 2012 9:36 am