Topic: Frequency Domain Filter Bug?

Hello,
i dont know so much about the Frequency Domain Filter but i think i fund a bug.
When i want to use this filter on images which are small (smaller than maybe 500x400 pixel) i get a abort and warning "Floating Point Error" .
That ist not really a problem while its only by small images.
But i think maybe its useful to report this.

2

Re: Frequency Domain Filter Bug?

I cannot reproduce this behavior - only with a 1x1 pixel image it behaves bad for me. What version of IA are you using?

Michael Vinther

> software developer <

Re: Frequency Domain Filter Bug?

Version 1.28 i am using

4

Re: Frequency Domain Filter Bug?

Ok, then the only thing I can suggest is to upgrade to 1.29.

Michael Vinther

> software developer <

Re: Frequency Domain Filter Bug?

ok i will do this :-)

Re: Frequency Domain Filter Bug?

I have a Question:
when i Paint by the FrequencyDomainFilter the Graph all Black, and then Process the Image, what is then left?
By me it is not nothing, it is the rest of a chromatic abberation.
When i subtract this rest image by the original i get off the LensErrors, very nice, but i understand not why?
which Frequency are Left when i paint all black?

7

Re: Frequency Domain Filter Bug?

Actually the frequency domain filter only works on the luminance plane (Y of YCbCr transformation) and ignores the chrominance planes.

Michael Vinther

> software developer <

Re: Frequency Domain Filter Bug?

Ok, but what happens when i Paint all black=?
Why is there a little Rest of something=?
Does a Tutorial for the Frequency Domain Filter exist?

To explain what i mean: I make Images with a selfmade/manipulatet Digicam, with i could use analog optics of old Minolta SLRs. The Lens i use had an Focuserror on the Red-Channel.
When i paint in the Frequency domain Filter all Black, the only thing which stays in the processed image is this "Error" a dark image with Red contures.
So i thought what a Luck i could know soubtract this Image by the original and get a really more sharp Picture (because the Red-Focus-Error does not Blur the Image after subtracting)

9

Re: Frequency Domain Filter Bug?

When you paint the FFT image black you simply set the Y plane of the YCbCr image to zeros but the Cb and Cr parts are left untouched. If you want to modify only the red plane of a RGB image you need to split it in RGB planes, modify the R plane and then recombine the planes to a color image.

Michael Vinther

> software developer <

10 (edited by blackberry8100 2009-08-20 8:27:44)

Re: Frequency Domain Filter Bug?

Marked! I will check it later!thanks a lot.
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Re: Frequency Domain Filter Bug?

But if the brightness (Y channel) is set to 0, then it should not matter what the color channels are because it should be black. Black IS brightness=0. So that explanation you gave makes NO sense.

12

Re: Frequency Domain Filter Bug?

Remember that we are in the frequency domain. Removing some selected frequencies doesn't mean that the image (or even part of it) becomes black.

Michael Vinther

> software developer <