Legacy ImageMagick Discussions Archive

More specifically, I'm looking at this:
http://imagemagick.org/Usage/fourier/#blurring
specifically the multiplication by circle/blurred circle.

You cannot do that.
1) there is no Gaussian:0x2 by itself
Right, I was wondering if I could automagically get one, in much the same way that I can automagically create a canvas using "-size 64x64 canvas:black".

2) -compose is associated with -composite and requires two images, generally the same ...

Is it possibly to multiply by a kernel, this could be very convenient. I'm trying variations of:

Doesn't work in png either. Tried a few flags and wasn't able to make any progress. scrot seems to be a working replacement for the time being.

I'm trying to use import to capture a screenshot. Namely as:

import -descend -window root screenshot.jpg

but I get annoying black boxes around all my system tray icons, any thoughts?

Assuming I have a grayscale image is there a good way of counting the fraction of pixels with a value above or below a cutoff value? I'm planning on determining if I am clipping on either end of the histogram, but I'm not quite sure how to proceed. My thought it maybe to apply a curve operator which ...

Both the magnitude and phase should have been the same format in my previous message.

Also, interestingly after transforming to phase space and back again the size of the image increased about 3 fold. But there seem to be little if any visually perceptible differences between the original and the ...

Well that only gives one output file, but I can't open it in the gimp. I guess I can play with the image in imagemagick later. Using ppm's for the intermediates seems appealing as I won't get errors from compression.

The previous other than the warning seems to work, so I may as well stick with it ...

I'll certainly try both (all) methods, hopefully some relative timings will be forthcoming in a bit.

I've started with the fft method and have successfully built imagemagick with fft support, and it seems to be working, but I get a
"convert: unbalanced parenthesis `)' @ error/convert.c ...

I would like to use in a script a very strongly blurred grayscale copy of an image and I am wondering at the relative speeds and advantage to the various methods

I am currently using the gaussian-blur, but will compare the results of the gaussian-blur to those of blur. Additionally, it seems I can ...

Sorry, I'm actually using convert -compose -composite (as suggested) and mangled it up in my attempt to post a minimum working example. So the ordering is correct. I'll try to update in original post.

I've switched to ppm from jpg and my error has gone down from 807.5 (0.012) to 667.7 (0.010). The ...

I tried two different ways of getting what I expect to be the same output, the first is:

C = A * mask;
output = C + B;

or in nearer IM syntax

composite -compose multiply mask A C
composite -compose plus C B output

and the second is

convert B A mask -compose plus -composite output

which should ...

What I arrived at (with linebreaks to improve readibility) is:

-fx 'iso=32;
rone=rand();
rtwo=rand();
myn=sqrt(-2*ln(rone))*cos(2*Pi*rtwo);
myntwo=sqrt(-2*ln(rtwo))*cos(2*Pi*rone);
pnoise=sqrt(p)*myn*sqrt(iso)*channel(4.28,3.86,6.68,0)/255;
max(0,p+pnoise)'

So you can see, while I needed a ...

I'm trying to compose an fx operation where

output value = max( 0, input value + value from normal distribution with sigma)

and I see I can get a random number, but I'd rather not make some crazy expression to go from uniform [0,1] random to normal random, besides doing so might be slow in ...

Fred,
I've posted some examples on the blog if you're interested (full size: http://www.flickr.com/photos/hwttdz/sets/72157626380901534/detail/ ). http://astoryworthtelling.wordpress.com/2011/03/28/smart-sharpening-in-imagemagick/

Have you tried the script? I'd be interested to know what you think ...