Re: Small Resize Quality
From: gak (email@example.com)
Date: Sun 06 Jan 2002 - 13:10:31 UTC
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Thanks for your response. To address this issue I tried to use some of the filters to remove the blur. Specifically I tried unsharpmask and conv sharpen. The conv sharpen worked GREAT (i.e. $scaled->filter(type=>'conv', coef=>[-0.2, 1, -0.2]);
Thanks for the help!
P.S. This is an AWESOME perl module. A big thanks to those that made it possible! THANKS!
The following message was sent by Arnar Mar Hrafnkelsson <firstname.lastname@example.org> on Fri, 4 Jan 2002 11:52:33 -0500 (EST).
> Typically when it comes to downsampling there is a little tradeoff between
> sharpness and noise in the scaled version. It's also possible that the
> scaling ratio is more important than the actual final size, then there
> a possible issue in the scaling code. It's also just possible that they
> look blurry if there is just too much high frequency in the image for that
> There was an issue in versions older than 0.39 where resizing could nasty
> artifacts. The downsampling method used is effectively a lowpass filter
> followed by decimation. The filter is a lancoz kernel, There are some
> parameters (that are not exported right now) which can be altered. One
> idea is to have a callback that specifies the lowpass filter to be used.
> -- Arnar
> On Fri, 4 Jan 2002, gak wrote:
> > Happy New Year!
> > I see a 'qtype' (quality type?) variable described under the Image Resizing
> section of the Imager documentation. Are there other settings other than
> > I've found that images resized by Imager to a relatively small size (100
> to 125 pixels wide) come through slightly blurry. Larger resized photos
> (400+ pixels wide) look GREAT! I'm wondering if a qtype=high setting exists
> to improve the quality for small images.
> > Anyone have experience with improving the quality of smaller images?
> Maybe there is another method.
> > Thanks!