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Image quality on resized images

Posted: Thu Apr 24, 2008 8:02 pm
by dstonek
I cannot see differences between setting 'quality=0' or 'quality=1' in scaling.properties.
I set 0.8 by default but I see artifacts on people faces so I made some test on extreme values.
Is there something I am missing?
I am resizing from 12Mp to 500 pixels max size.
The differences between this photos and the Irfanview's (a nice program to handle images) generated ones are appreciable.
Thank you
PS: In all quality setting the jpeg file size is 35Kb Irfanview's 42Kb (80/100 qual)

Re: Image quality on resized images

Posted: Thu Apr 24, 2008 8:23 pm
by support
Try values from 0.05 to 1.0, you will see the differences. For 0.1, JPEG compression is good but image quality is very bad. For 1.0, quality is perfect but image size is big.

Re: Image quality on resized images

Posted: Thu Apr 24, 2008 10:18 pm
by dstonek
I aaaaalways forget to clean the java cache. To do this in Firefox I have to close and open the program.
500x380 pixels takes around 174kb (this image) in quality 1
35Kb in quality 0.6
49Kb in quality 0.8

Is it possible to control sharpening amount?
I would prefer less filtering.
Thank you.

Re: Image quality on resized images

Posted: Fri Apr 25, 2008 8:03 am
by support
No, this feature is not available. But it could be a good idea. Do you a have link that explain the basics of such filtering ?

Re: Image quality on resized images

Posted: Fri Apr 25, 2008 12:16 pm
by dstonek
Well, I've read something about sharpening several years ago but I don't have a modern link.

Re: Image quality on resized images

Posted: Sun Apr 27, 2008 12:20 pm
by support
I've found this one:
http://www.photoshopsupport.com/tutoria ... ening.html

Does it fit to your definition ?