PIL: retreive image resolution (dpi)

[AlexGreif.2609394]

Hi,
I looked at the PIL Image class but cannot see a posibility to retreive
the image resolution dots per inch (or pixels per inch)

Could somebody
please tell me how to get these metadata infos in PIL?

thanks,
Alex.

[and-google]

Al***************@bloglines.com wrote:

I looked at the PIL Image class but cannot see a posibility to retreive
the image resolution dots per inch (or pixels per inch)

Not all formats provide a DPI value; since PIL doesn't do anything with
DPI it's not part of the main interface.

For PNG and JPEG at least the value may be retrievable from the extra
info dictionary (image.info['dpi']) when loaded from a file that sets
it. Expect an (x, y) tuple (not necessarily square-pixel).

--
And Clover
mailto:an*@doxdesk.com
http://www.doxdesk.com/

[Terry Reedy]

<an********@doxdesk.com> wrote in message
news:11*********************@g44g2000cwa.googlegro ups.com...

Al***************@bloglines.com wrote:

I looked at the PIL Image class but cannot see a posibility to retreive
the image resolution dots per inch (or pixels per inch)

Not all formats provide a DPI value; since PIL doesn't do anything with
DPI it's not part of the main interface.

Digital images intrinsically have a size in pixels, not a 'resolution'.
Resolutions (dpi or whatever) represent relationships and transformations
between images and physical substrates. Somes images have an input
transform, though for digital cameras, the input dpi or dpm(illimeter) of
the ccd imager is seldom useful. Some have one *or more* output
transforms. Some have both. So I think the option i/o transforms are best
thought of and kept as 'extra' data. (The same applies to strings and I/O
formats.)

Terry J. Reedy
Terry J. Reedy

[Do Re Mi chel La Si Do]

Hi !
The size of a image is an element ; but resolution is another. It is the
link, between the image and the reality. Size AND resolution can to give the
scale.

Exemple : when you scan a document, the size (in pixels) is not sufficient,
for to reproduce the document. Size + resolution, yes.
@-salutations

Michel Claveau