Thanks for the vips link (needs a www. BTW) .
I was not expecting you to dig the code just some thoughts on the DFT but if you're busy , 'nuff said.
Sorry I was forgetting that jinc is a convolution kernel in the EWA context. No DFT. So irrelevant to this thread.
Search found 88 matches
- 2012-01-03T08:55:57-07:00
- Forum: Digital Image Processing
- Topic: proper scaling of the Jinc filter for EWA use
- Replies: 234
- Views: 608806
- 2012-01-03T06:30:01-07:00
- Forum: Digital Image Processing
- Topic: proper scaling of the Jinc filter for EWA use
- Replies: 234
- Views: 608806
Re: proper scaling of the Jinc filter for EWA use
Hi Nicola, if you have time could you look at this post I sent to the bugs forum? Your expertise in maths may help clarify what IM is or isn't doing and whether it is correct. http://imagemagick.org/discourse-server/viewtopic.php?f=3&t=20102 If fft is in some way producing less than rigorous res...
- 2012-01-03T06:19:05-07:00
- Forum: Digital Image Processing
- Topic: proper scaling of the Jinc filter for EWA use
- Replies: 234
- Views: 608806
Re: proper scaling of the Jinc filter for EWA use
Yes, I think gamma is relevant. I was suggesting this to Fred in recent days w.r.t. deblur et al. Gamma is a non-linear transformation and so it will have an affect on the result. I would expect this to affect colour balance more than ringing/blurring. Is there some kind of statistic that IM could p...
- 2012-01-03T04:49:56-07:00
- Forum: Bugs
- Topic: FFT phase ?
- Replies: 19
- Views: 39474
FFT phase ?
Hi, I am having some doubts as to whether -fft is producing the correct phase data. (Or perhaps documentation is incomplete as to what it is _supposed_ to produce). I'm looking at the DFT of simple straight line segment that can be used to simulate a motion blur: http://www.fmwconcepts.com/imagemagi...
- 2012-01-03T00:04:26-07:00
- Forum: Digital Image Processing
- Topic: proper scaling of the Jinc filter for EWA use
- Replies: 234
- Views: 608806
Re: proper scaling of the Jinc filter for EWA use
Of course, it was right in front of me all the time !
Why don't we use some of the russian tarts that adorn my screen every time I visit this forum ???
Why don't we use some of the russian tarts that adorn my screen every time I visit this forum ???
- 2012-01-02T23:58:41-07:00
- Forum: Digital Image Processing
- Topic: proper scaling of the Jinc filter for EWA use
- Replies: 234
- Views: 608806
Re: proper scaling of the Jinc filter for EWA use
the Kodac suite (24bit PNG) http://r0k.us/graphics/kodak/ has a girl in red hat that looks suitable. Preamble says images are "for unrestricted usage". http://r0k.us/graphics/kodak/kodak/kodim04.png Between the smooth flesh tones and freckles that should some provide fairly exacting tests.
- 2012-01-02T09:24:40-07:00
- Forum: Digital Image Processing
- Topic: proper scaling of the Jinc filter for EWA use
- Replies: 234
- Views: 608806
Re: proper scaling of the Jinc filter for EWA use
Well, blur=0.943159799432847711 is a tad sharper with all that that implies. More jaggies on tripod, sharper look overall, slightly more intense look of concentration for the cameraman. I think the most accurate is a straight jinc3 without the deblur. With blur=0.88549061701764 I see a bit of roughn...
- 2012-01-02T00:00:09-07:00
- Forum: Digital Image Processing
- Topic: proper scaling of the Jinc filter for EWA use
- Replies: 234
- Views: 608806
Re: proper scaling of the Jinc filter for EWA use
http://www.fmwconcepts.com/imagemagick/fourier_transforms/images/cameraman.png could I suggest you take a look at this as a test image. While not a block graphic, it does have high contrast edges and sharp diagonals which are useful picking up some defects in various filters. I just ran the followi...
- 2012-01-01T12:03:59-07:00
- Forum: Digital Image Processing
- Topic: proper scaling of the Jinc filter for EWA use
- Replies: 234
- Views: 608806
Re: proper scaling of the Jinc filter for EWA use
I would expect 2 lobe versions to be too soft. They are cropped too early and deviate too much from the idea function to be sharp. Be sure to give equal testing time to block graphics. Nice photos like rose: will be a lot less susceptible to harsh ringing and results may lead to conclusions that are...
- 2011-12-30T00:09:00-07:00
- Forum: Bugs
- Topic: bad error trapping could cause unexpected shell commands
- Replies: 8
- Views: 17125
Re: bad error trapping could cause unexpected shell commands
thanks for the clarification.
Do you have any comment on the subject of this thread, that premature abortion of command line parsing can cause basically arbitrary residual text to be executed by the shell?
Do you have any comment on the subject of this thread, that premature abortion of command line parsing can cause basically arbitrary residual text to be executed by the shell?
- 2011-12-29T12:18:43-07:00
- Forum: Users
- Topic: roll and blur
- Replies: 4
- Views: 10398
Re: roll and blur
thanks, that gives me some homework for tonight ;) That looks like I should be able to do exactly what I want with a bit of digging. what did already was this wid=`identify -format "%w" $src` half=$(($wid/2)) blur=52 convert -gravity Center $src \ -roll +$half+0 \ -region 6%x100% -blur 3x$...
- 2011-12-29T05:28:08-07:00
- Forum: Users
- Topic: roll and blur
- Replies: 4
- Views: 10398
Re: roll and blur
Thanks I have managed to blur a +/-5% strip that I rolled to centre and then back afterwards, repeated in x and y. This drastically reduces ringing due to boundary discontinuities, however, it's very clumsy. what would be nearer to what is needed is a progressive blur, like a linear gaussian blur wi...
- 2011-12-29T05:16:15-07:00
- Forum: Digital Image Processing
- Topic: proper scaling of the Jinc filter for EWA use
- Replies: 234
- Views: 608806
Re: proper scaling of the Jinc filter for EWA use
Can't think of a good method at this time. The big problem is that images only store a interger from 0 to 2^16-1 (for IM Q16) and Jinc has negatives. You would need HDRI or some type of offset, to do it properly. One thing I could do is map Resampling filters to Convolve/Morphology Kernels! But tho...
- 2011-12-29T01:16:31-07:00
- Forum: Digital Image Processing
- Topic: proper scaling of the Jinc filter for EWA use
- Replies: 234
- Views: 608806
Re: proper scaling of the Jinc filter for EWA use
As a result of some testing using windowed jinc on deblur it appears that there is not one "best" choice , indeed windowing is not always advantageous. As I said elsewhere I think some more thought needs to go into why the window is there and what it is supposed to achieve rather than subj...
- 2011-12-26T17:14:48-07:00
- Forum: Bugs
- Topic: bad error trapping could cause unexpected shell commands
- Replies: 8
- Views: 17125
Re: bad error trapping could cause unexpected shell commands
that's great news.
IM is really powerful but it's usefulness is severely reduced by the arcane commands. I'm sure a thorough restructuring of the CLI would make it much more accessible.
Looks like , by the time I master the current command set , it'll be out of date. LOL.
IM is really powerful but it's usefulness is severely reduced by the arcane commands. I'm sure a thorough restructuring of the CLI would make it much more accessible.
Looks like , by the time I master the current command set , it'll be out of date. LOL.