Re: Installation Question: Debian 12, GraphicsMagick 1.3.42, JasPer 4.0

On Sat, 30 Sep 2023, Matthias Schmitt via Graphicsmagick-help wrote:
>>
>> If you use GraphicsMagick to open and look at a JP2 file that was written, does it visually look similar to the input image?
>
> Yes, you are right. All JP2 test images seem to be created 
> correctly. When I convert images using the gm tool, JP2 images get 
> generated and they look flawless. I double checked that the 
> resulting files are really in JPEG 2000 format and not another 
> format.

It seems that the maximum error (e.g. 0.143998661477254) is a bit 
high.  The read/write tests allow a maximum error of 0.06 for JPEG 
2000.  The same is used for WebP and classic JPEG.  These have not 
failed up until now.

It is interesting that the tests work for me.

What compiler and compiler version are being used?  What options were 
used while building JasPer?

What GraphicsMagick configuration options did you use?

What type of hardware are you using?

It is worthwhile to try using the 'jasper' utility to perform 
conversions (e.g. from reference.jp2 to output.jp2) and then use

   gm compare -metric PSNR  reference.jp2 output.jp2

to see some error metrics.

JasPer also provides a similar means to compare two images.

You could also start from a lossless format supported by JasPer and 
use that original as the reference.

Bob
-- 
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
Public Key,     http://www.simplesystems.org/users/bfriesen/public-key.txt