[Zope] Re: image hot fix

[seb bacon]

* Ron Bickers <rbickers-dated-999542769.b3b605@logicetc.com> [010827 19:55]:
> > So maybe you could give a look at ImageMagick, especially the "mogrify"
> > command. I've used it only from os.system, but AFAIK there's a python
> > module for ImageMagick which may produce better results than PIL
> > (untested), it's called PyMagick IIRC.
> 
> I've been running some tests with my Photo product that uses PIL and
> comparing it to the output of mogrify and I can barely tell any difference
> in any of the rendered images.  I've resized 1024x768 JPG to 480x'whatever'
> and 128x'whatever' and I don't see enough difference to say ImageMagick is
> better.  In fact, parts of the image seem better with PIL and other parts
> with IM.  Am I missing something?  What options should I be using for
> mogrify?

I'm afraid I just don't have time to gather the evidence right now,
but unless I've made some huge mistake, there are definitely problems
with the PIL resizing output quality - I've seen 'jagged edges' too.
The tests you mention are scaling images by powers of two (i.e. 480 =
1024 / 2, 128 = 1024 / 2^3) which will minimise the number of
rounding errors (I'm guessing a bit - can you tell? ;-).  Have you
tried scaling down by 1/3, 1/7, etc?

> If people are disatisfied with PIL resizes, I'd like to provide an
> alternative, but IM isn't nearly as Python friendly.

I'm still not clear of the _disadvantage_ of having to do an
os.popen() call, or similar?

cheers,

seb