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IM6 vs 7: Convolve with bias 50% differ
Posted: 2014-12-26T05:43:44-07:00
by 7eicher
Hi folks,
I was using convert in IM6 to create the edges with the convolve method successfully like that:
Code: Select all
convert file.jpg -bias 50% -morphology Convolve loG:0x2 edge.jpg
Using now IM7 with the exact same command results in a totally white image:
Code: Select all
magick file.jpg -bias 50% -morphology Convolve loG:0x2 edge.jpg
Is this intentionally or a bug? I am using for IM7 this windows pre-build from
http://blog.astrophotographytargets.com ... n-windows/ with FFTW support.
Source image:
IM6 bias 50%:
IM7 bias 50%:
IM7 bias 0%:
Re: IM6 vs 7: Convolve with bias 50% differ
Posted: 2014-12-26T07:37:46-07:00
by snibgo
That version is two years old. So it will have whatever bugs v6 had at that time, plus whatever bugs were introduced by the pre-release v7.
You might try this with a recent build of v7.
If I were you, I would use v7 only for operations that need it. In your case, this is just fft.
Re: IM6 vs 7: Convolve with bias 50% differ
Posted: 2014-12-26T08:39:52-07:00
by 7eicher
makes sense... thanks!
Re: IM6 vs 7: Convolve with bias 50% differ
Posted: 2014-12-26T11:19:03-07:00
by fmw42
I have tested your command and image on my Mac OSX Snow Leopard with IM 6.9.0.0 Q16 and IM 7 beta Q16 HDRI (Dec 20, 2014) and the two results agree visually. However, they are somewhat different (and likely more correct) than your IM 6 version. Your LoG 0x2 looks too sharp. You do not say what version of IM 6 you are using and it might be old or have a bug. Always best to identify your version of IM and platform.
Re: IM6 vs 7: Convolve with bias 50% differ
Posted: 2014-12-26T11:49:41-07:00
by fmw42
Installation of FFTW on Windows and Ubuntu can be found at
viewtopic.php?f=4&t=14251