Search found 88 matches

by imaggie
2011-12-26T12:52:57-07:00
Forum: Users
Topic: tiling trouble
Replies: 4
Views: 7601

Re: tiling trouble

thanks again. that's the second biggest problem with IM , the doc is about an anarchistic as the syntax. If found the "doc" for the tile option but it was so brief as to be useless. http://www.imagemagick.org/script/command-line-options.php?#tile There has clearly been a huge amount of work gone int...
by imaggie
2011-12-26T12:39:41-07:00
Forum: Bugs
Topic: bad error trapping could cause unexpected shell commands
Replies: 8
Views: 14729

Re: bad error trapping could cause unexpected shell commands

thanks very much for you help. The biggest problem I find with IM is that just about every command is an exception ;) The amount of possibilities of what one can do with IM is amazing, but so it the amount of work and reading required to get there. :( I'm sure this is the result of years of bolt-on ...
by imaggie
2011-12-26T08:06:07-07:00
Forum: Bugs
Topic: bad error trapping could cause unexpected shell commands
Replies: 8
Views: 14729

bad error trapping could cause unexpected shell commands

Hi, through struggling with IM syntax I make frequent errors. Several of these has pointed out what looks like it could be an exploit. convert -size $((5*$wid))x$((5*$ht)) xc: -tile (-extract 50%x25%+25%+5% tile.png)\ -draw "rectangle 0,0 $((5*$wid)),$((5*$ht))" \ output-tile.png It seems the parser...
by imaggie
2011-12-26T07:45:23-07:00
Forum: Users
Topic: tiling trouble
Replies: 4
Views: 7601

tiling trouble

Hi, I need to tile a new image with a repeated section of a base image. I can't seem to get the right syntax for any of the many ways to do tiling. So far I can crop the bit I need and create an image with one copy but cannot tile it. convert -size $((5*$wid))x$((5*$ht)) xc:black \ tile.png -crop 50...
by imaggie
2011-12-25T11:26:31-07:00
Forum: Digital Image Processing
Topic: proper scaling of the Jinc filter for EWA use
Replies: 234
Views: 424194

Re: proper scaling of the Jinc filter for EWA use

I can't recall the details but I think Lanczos being a rigorous mathematician did actually have sound theoretical reasons for his choice. My point was that the fact that sinc-sinc works well is not reason to suppose jinc-jinc it necessarily the best way to do for EWA. I don't understand your use of ...
by imaggie
2011-12-21T09:17:17-07:00
Forum: Digital Image Processing
Topic: proper scaling of the Jinc filter for EWA use
Replies: 234
Views: 424194

Re: proper scaling of the Jinc filter for EWA use

NicolasRobidoux wrote:Apparently, what imaggie needs is to transform a windowed Jinc into a mask (so he/she can apply it in Fourier domain?).

Anybody knows how to do that?
Yes , sorry if that was not clear from my earlier post.
by imaggie
2011-12-21T09:13:11-07:00
Forum: Digital Image Processing
Topic: proper scaling of the Jinc filter for EWA use
Replies: 234
Views: 424194

Re: proper scaling of the Jinc filter for EWA use

... jinc is the FT of the cylinder but the window fn is not specifically related to, say, the FT of the rectangular image array. So there is no 'right' answer there. Single sinc lobe seems a good choice for orthogonal so a rotation of that would seem a good choice for a circularly symmetric fn like...
by imaggie
2011-12-21T07:01:14-07:00
Forum: Users
Topic: roll and blur
Replies: 4
Views: 8860

roll and blur

I am trying to reduce ringing around lettering in an FFT processing with a mask jinc mask. It seems that much of the ringing is due to strong components in the middle of the frequency range caused by image border discontinuities. I would like smooth this transition by rolling the image 50% and blurr...
by imaggie
2011-12-20T05:35:03-07:00
Forum: Digital Image Processing
Topic: proper scaling of the Jinc filter for EWA use
Replies: 234
Views: 424194

Re: proper scaling of the Jinc filter for EWA use

PS the (original) script has a "slow" option that, apart from interpolation errors does that same thing. The result is indistinguishable in reality in the square case to which it is currently restrained. convert -size ${w1}x${h1} xc: -monitor \ -fx "zz=hypot($fxd*(i-$cx),$fyd*(j-$cy)); (zz<=3)?$jinc...
by imaggie
2011-12-20T02:30:26-07:00
Forum: Digital Image Processing
Topic: proper scaling of the Jinc filter for EWA use
Replies: 234
Views: 424194

Re: proper scaling of the Jinc filter for EWA use

Thanks for your replies. I'm looking into removing defocus blurring. So, no it's not orthogonal. The application is different but it seems all the windowing and function discussions will be an exact parallel with the same issues. Hopefully we'll get two for the price of one at the end of the day. I'...
by imaggie
2011-12-19T13:55:41-07:00
Forum: Digital Image Processing
Topic: BC-splines with 2C+B=1 are optimal for EWA resampling
Replies: 41
Views: 112773

Re: BC-splines with 2C+B=1 are optimal for EWA resampling

I would suggest finding another name than "lanczos" for jinc-jinc. firstly it's confusing because it is not a lanczos filter (sinc-sinc) and secondly out of respect for Lanczos who was a thorough and brilliant mathematician and does not deserve to have his name recycled and given to something he did...
by imaggie
2011-12-19T09:44:59-07:00
Forum: Digital Image Processing
Topic: proper scaling of the Jinc filter for EWA use
Replies: 234
Views: 424194

Re: proper scaling of the Jinc filter for EWA use

Quite a coincidence seeing this being actively discussed just now . I'm looking at this question of jinc-jinc vs sinc-jinc and window fn extent. Am I correct in thinking your conclusion is that they both seem to perform similarly in quality but that jinc-jinc falls off rather too quickly , giving pr...
by imaggie
2011-12-19T09:34:08-07:00
Forum: Digital Image Processing
Topic: search for a decent interpolatory EWA filter
Replies: 17
Views: 48636

Re: search for a decent interpolatory EWA filter

Hi , just chipping in on this , catmull-rom spline is used for interpolation in gimp. By definition it passes though all four reference points so would seem to fit your no-op criterion. It can tend to overshoot on steep changes but that is more or less a result of containing it to pass through all f...