[PIL]: Image size in runtime

[Andrea Gavana]

Hello NG,

sorry if the message is not strictly Python-related, but it is
fantastically impossible to send post to Image-SIG.
I am using PIL to load and display some pictures (via wxPython) in a
GUI. I have added the ability for the user to change the linear
dimensions of the image (in pixels) and the quality of the image in
order for the image to be saved in another file.
I was wondering if is there a way to know in advance, based on the
pixel dimensions specified by the user and by the image quality, which
file size (in
bytes) I will obtain for the new image (approximatively). Is there a
way to obtain such result without actually saving the image?

Thanks for any hint.

Andrea.

"Imagination Is The Only Weapon In The War Against Reality."
http://xoomer.virgilio.it/infinity77/

 

[Scott David Daniels]

I am using PIL to load and display some pictures (via wxPython) in a
GUI. I have added the ability for the user to change the linear
dimensions of the image (in pixels) and the quality of the image in
order for the image to be saved in another file.
I was wondering if is there a way to know in advance, based on the
pixel dimensions specified by the user and by the image quality, which
file size (in
bytes) I will obtain for the new image (approximatively). Is there a
way to obtain such result without actually saving the image?

The answer is really no, since it depends on the complexity of the
picture. A solid square of one color is highly compressible, and a
photo of a tall ship's rigging is relatively hard to compress. You
can compress to a cStringIO file (and so not have to actually hit
the disk) to get a size, ten discard the cStringIO object.