[Image-SIG] Aliasing problem using PIL ..

Bryan Lawrence b.n.lawrence@rl.ac.uk
Mon, 3 Feb 2003 09:12:03 +0000

Hi Folks

Isn't it amazing how sharing a problem immediately concentrates your mind?

Firstly, Brandon is right, it's the top left, and that's what I wanted it to 
do, I just commented it for the list in a hurry ... wrongly ...

In the process of putting the jpg files on a website in reply to Bradon's 
email and to avoid filling folks inboxes, I used something else to view the 
files, and discovered that the aliasing problem is not in the output image, 
but in 
  a) the packages which squeeze the image up to fit on my display, and
  b) possibly, their printer drivers.
(I had tried two different viewers ... obviously not enuff ...) So, after 
troubling you all, there is nothing wrong with the output of this programme, 
everything is wong with what I do next (or with the concept). 

Can I restate my (new) problem in two parts?

Firstly, what i'm trying to do is produce an output image which loses as 
little as possible of the resolution of the input images, so I'm aiming to 
produce the output as close as possible to the desired print resolution.  
(That's why it's a 4800x6600 image, which ought to be 8 inches by 11 inches 
at 600 dpi - not 300 as I said in my badly commented snip
of code).   Does that make sense? 

Secondly, what's a sensible way of getting such an image to a printer
with the minimum distortion introduced by an image display printer driver? 
Is there a good package under linux (suse 8.1). (Given that the target printer 
is a psc2115 using the hpoj/hpijs combination)

Once again, apologies, I feel like these are rather trivial questions, but 
I'm new at this, and I don't know where else to ask.

Thanks in advance,

On Sunday 02 February 2003 19:35, Brandon Craig Rhodes wrote:
> Bryan Lawrence <b.n.lawrence@rl.ac.uk> writes:
> > anyway, the following piece of code works but doesn't give the
> > quality of results i expected.
> My results upon running it were to get the image, with its normal size
> and appearance, in the upper-left (not upper-right - my copy of PIL
> seems to count coordinates from the upper-left) of an absolutely
> enormous 4800x6600 canvas (well, enormous for my 1024x768 display).
> To view the large image I can either pan across it, which makes my
> image look normal-sized on the screen, or I can shrink the view to fit
> on my screen, in which case I see the image - quite appropriately -
> rather small and in the upper left corner.
> If you could provide for us the test image *and* the bad-looking
> output image you are getting, we could probably be of much more
> assistance to you.