[Image-SIG] Help w/ resize

[kcaza@cymbolic.com]

Basically, you just need to find out the aspect ratio of the new file at 275
pixels wide, and resize it using that size.  It's pretty simple.

##############
import Image

def BetterThumbnail(im, xmax, ymax):
     inaspect =float(im.size[0])/ float(im.size[1])
     outaspect = float(xmax) / float(ymax)

     if inaspect > outaspect: # meaning that xmax will be used in resizing, and
y will be determined by aspect ratio
          im = im.resize((xmax, int((float(xmax) / inaspect) + 0.5)),
Image.BICUBIC) # round it off, resize with Bicubic
     else: # meaning that ymax will be used in resizing, and x will be
determined by aspect ratio
          im = im.resize((int((float(ymax) * inaspect) + 0.5), ymax),
Image.BICUBIC)

     return im

################

That should do it for ya... check it out with a couple test images though, it's
similar to what I use in my stuff, but not exactly the same.

Kevin.





Jason Long <jason@streetrodstuff.com> on 05/15/2000 07:14:43 AM

To:   image-sig@python.org
cc:    (bcc: Kevin Cazabon/cymbolic/gig)

Subject:  [Image-SIG] Help w/ resize




Hi, I am a newbie to the PIL library and I need a little help.

For the record, I am using Python/PIL on Redhat 6.1 - Python version 1.5.2.

Here is my scenario:  I have some images of all different sizes that I would
like to resize to a size of 275 pixels wide, and I don't care how tall.  I want
to preserve the aspect ratio, though.  I have had success with the thumbnail()
function, however the image quality is not very good.  I was thinking that I
would get better results with resize() since I could specify BILINEAR or BICUBIC
filters.  I guess I am not exactly sure how to use the resize function correctly
for my needs.

To summarize, I need to:
- resize images of different sizes to (275, x)
- generate the best quality I can

Basically, I'd like the thumbnail functionality with better output quality.  I'm
sure I'm simply not doing something correctly.  Perhaps a snipet of code would
do me best.

Thank you very much in advance.

Jason

--
Jason Long
Webmaster http://www.streetrodstuff.com


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