Legacy ImageMagick Discussions Archive

I disagree with the assertion "The same thing happens in convolutions, where the weighted averaging of values make the actual range of the values being used of little consequence, alpha weighting or otherwise." This was exactly the problem I reported at the beginning of this thread, when m...

Let's hope for the best! Hopefully IM 7 will adopt the double precision representation, fix these problems, and make it more robust. Right now it makes me wonder if the errors in built in operations like convolution and such are not too detrimental and results reliable. Thanks for the ImageJ tip. Be...

Thanks for the tip. Unfortunately this is a cumbersome solution and probably not right when using high order polynomials (my primary motivation when I started this thread) specially when the polynomial order is only known at run time. Also, for numbers larger than 15 all gets mapped either to 255 (s...

Unfortunately it is the [0.0, 1.0] representation of color/intensity values that is troublesome. It is a smart decision to adopt a canonical representation, to have a uniform way to seamlessly handle all possible different quantizations, but it seems that has its drawbacks as it was shown by the mul...

I don't know the internals of IM but wouldn't using double and, if needed, quad precision floating point numbers to perform the operations be sufficient? Only after the operations are done results would be mapped to whatever quantization is necessary to hold the numbers. No need for normalization he...

By the way, for completeness, the platform I ran the tests above is Linux Ubuntu 11.04 natty and IMagick 6.6.3-8 (6.6.2-6 2011-03-16 gives the same problem) Linux XXX 2.6.38-8-generic #42-Ubuntu SMP Mon Apr 11 03:31:24 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux Version: ImageMagick 6.6.3-8 2010-08-21 Q...

Calling convert mock.pgm -depth 16 -evaluate pow 2 mock-square.pgm to compute the square value of each pixel in the input image mock.pgm is producing odd results, i.e., the resulting numbers are not actually the square values and they are off by quite a margin of error. I made sure square values of ...

Here is the classical reference to the area opening and closing topic: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.125.6317&rep=rep1&type=pdf The idea is more or less the following (area closing for binary images): find the connected components in the image and paint with backgr...

Thanks for the detailed answer and information. I now know that using multiple kernels in a single call to thinning is detrimental to speed. I will make changes accordingly. I will try the debugging you suggested to see what is happing under the hood. I am satisfied with Skeleton:2 and will continue...

Thanks for the link and for documenting the morphology suite. I have been using it extensively and it has been very very useful. Area opening and closing are different from opening and closing with a structured element (kernel) as they are not shape related but simply area related (sometimes called ...

Is there any equivalent of area opening and area closing in IM ? These are operators that can remove and fill binary regions having at least a given number of pixels (area size). They are very useful to remove undesired tiny spots before e.g. a thinning operation. They are shape independent so defin...

I have found differences in results when performing the following thinning operations on a B&W image: convert img.pgm -morphology Thinning:-1 'Skeleton:1;Corners' thin.pgm convert thin.pgm -morphology Thinning:-1 'LineEnds:-1;Peaks:1.5' -depth 1 result_1.pgm and combining both thinnings in a sin...

Thanks for replying and willingness to take a look at the problem and apologies for not posting an example image sooner.
You can find the image.tif file mentioned in my previous post here: http://www.imagenoir.com/magick/
Hopefully there is a way IM can handle such images.

I would like to use IM to work on some tiff images that were extracted from a multipage microscopy file (.lsm, Zeiss format, tiff based). The problem I think I am having is that there are 2 channels only on the tiff files (see below) and IM can't quite work with that. For example, % convert -separat...

Does IM compute convex hull of binary images ? I have many binary images with a single (connected component) object in each image. Is there a way to use IM to determine the convex hull of the foreground object in a binary image and then paint its interior and produce another image with same size as...