[Image-SIG] Resizing images

[Matthew Nuzum]

Well, the only way to know for sure is to try it... you could probably
whip up a quick and dirty solution in 1-2 hours.

And, while I'm sure PIL is as good or better than ImageMagick,
different algorithms can sometimes produce different results, so you
want to try it out too to see which works best for your art.

By the way, I don't know what's going on behind the scenes here, but
he obviously uses Python, so maybe PIL too. This is a cool project,
though not OSS: http://snipshot.com/

On 2/22/07, Chris MacKenzie <chris at sunnyneuk.com> wrote:
> Hi Mathew,
>
> Thanks for helping out. Yeah you can do the old droplet thing.
>
> In my limited experience of CS2, though, I define a new resize action if I
> want to modify an existing one.
>
> Also, I have two sets of actions one for portrait and one for landscape
> images to produce the same four constants; A3, A4, Email, Web and I want to
> add ebay and Alamay.
>
> Also, things just seem to get a bit too cluttered for my ordered world.
>
> It just seems cool and simple in my programmers brain if everything is in a
> python script or similar that checks out width > height and uses the correct
> sizes.
>
> Chris
>
>
> ----- Original Message -----
> From: "Matthew Nuzum" <newz at bearfruit.org>
> To: "Chris MacKenzie" <chris at sunnyneuk.com>
> Cc: <image-sig at python.org>
> Sent: Thursday, February 22, 2007 2:58 PM
> Subject: Re: [Image-SIG] Resizing images
>
>
> > On 2/20/07, Chris MacKenzie <chris at sunnyneuk.com> wrote:
> >> I am doing a vast amount of work in photoshop cs2 and then resizing
> >> images
> >> into multiple sizes for email, web publication, printing out on A3, A4
> >> etc,etc. To date I have been using PhotoShop actions which is a real
> >> pain.
> >
> >> My Question is will resizing in PIL reduce the image quality compared to
> >> CS2
> >> or will it remain the same as the CS2 output.
> >
> > I'm not a hard-core pil dev/user, but I've been in the same boat as
> > you, so here's my thoughts:
> >
> > With Photoshop you'll be working from high-res, lossless files (PSDs).
> > If you were to save them out as a high-res jpg and then resize that
> > into smaller files with PIL, you'd definitely loose some quality,
> > since PIL's source material (JPGs) will be of lower quality.
> >
> > If you give PIL a non-lossless format, like 24/32b PNGs and you resize
> > to even multiples of the source image's size (for example, 800x600 -->
> > 400x300 --> 200x150 --> 100x75) I suspect you'd get pretty similar
> > results.
> >
> > Where Photoshop shines, in my experience, is:
> > * resizing to non-even multiple of source image's size (800x600 --> 90x68)
> > * using masks to define different compression ratios for different
> > parts of the image
> > * choosing the best compression ratio to match your desired output
> > size/quality
> >
> > This is just a guess though. Since Photoshop is a proprietary program,
> > no one outside Adobe can be confident about what goes on inside its
> > "save optimized" code. Maybe PIL can do better!
> >
> > Also, different types of photos may be affected differently by the
> > various programs. Line-art may look rotten and photos may look superb.
> > You could batch them and then fix up anything that doesn't look good
> > enough.
> >
> > By the way, I'm surprised you felt using actions a pain... don't you
> > just drop a folder of images onto your action's "droplet" .exe file? I
> > don't use cs2, so maybe they've taken droplets out.
> > --
> > Matthew Nuzum
> > www.bearfruit.org
> > newz2000 on freenode
> >
>
>
>
>


-- 
Matthew Nuzum
www.bearfruit.org
newz2000 on freenode