Where would I find the exact algorithm for generating a Data Matrix ECC200 bar code image that would eventually be printed? I've seen plenty of general explanations but nothing sufficient enough to write code from. I realize of course that there are libraries for this but I'd like to reinvent this particular wheel.
The datamatrix symbology is defined by the standard ISO/IEC 16022 available at:
https://www.iso.org/standard/44230.html
If you poke around the web a bit, you may find a copy....
Related
I'm interested in implementing the Fast Multipole Method to efficiently simulate a system of repulsive particles.
I've found a large collection of references discussing FMM, but none seem very approachable for non-mathematicians who want to fully understand the algorithm.
Can you recommend a ground-up reference that clearly explains the mathematics behind the process, and includes pseudocode exemplifying a proper implementation?
I am by no means an expert in FMM, but this java implementation and introduction is the best source I've found so far for explaining it carefully and slowly. The paper is good at defining terms before using them, and the code at least is useful as a reference point. The math still gets hairy very quickly, but it is what it is :)
A pedestrian introduction to fast multipole methods is a close second. It doesn't explain the actual details of a working FMM implementation, but it's a good introduction to the basic ideas.
I like the short course on FMM. In begins with FMM in 1D, than it uses theory of complex variable to do FMM in 2D. And than there is the crazy 3D version which uses theory of spherical harmonics functions, which I guess can be very difficult for non-mathematician. But If you need FMM only in 2D you should be fine.
Unfortunately no pseudo codes are given there.
But do you really need the accuracy of FMM?. You might be fine with Barnes-Hut's algorithm
After running into a similar issue to you, I ended up writing a fully-documented Python fast multipole method implementation, pybbfmm. I've also written a short, mathematics-free tutorial on how the method works. Together, I think they're substantially more accessible than any of the other presentations I could find.
(meta: Although this is effectively a linkpost, the OP is explicitly asking for a link. I've added what I think was missing from the last one - the name fo the library - but I'm not sure how else to offer this answer except as a name and a link. Certainly it doesn't feel any more linkpost-y than the accepted answer. If this one gets deleted as well, I'll give up)
I want to extract an object such as a man ,a car or something like that from an image.The image is just an ordinary iamge, not medical image or other types for specific purpose.
I have searched for a long time and found that the automatic image segmentation algorithms just segment the image into a set of regions or gives out the contour in the image,not a semantic object. so I turned to the interactive image segmentation algorithms and I found some popular algorithms like interactive graph cuts and SIOX and so on. I think these algorithms just meet my demand.
Further more, I also downloaded two interactive image segmentation tool,the first one is the interactive segmentation tool, the second one is the interactive segmentation tool-box.
So my quesions are
1.if the interactive image segmentation algorithm is the right solution for my task since the performance is the most important.
2.and if I want to use the automatic image segmentation algorithm, what should I do next?
Any suggestion will be approciated.
If you want to pick out a object from a single static image just by a few scribbles. I recommend you have a read of
'Closed-form solution to image matting'
or 'Spectral matting',
or 'lazy snapping'
but as in my tests, the last doesn't perform as well as the first two methods when dealing with subtle objects like hairs.
However you can find their source matlab codes very easily from google.
But the first two method are't so pleasant to use actually, I think you'll need to do lots of modification to make them easy to use. It's main problem IMHO, is it requires very decent scribbles on the image, that's if you draw some extra scribbles or at wrong positions, you'll ruin your object cutting .
Apart from these, you may try 'bayesian matting, possion matting, etc.' which all request some helping image called trimap, and it's hard to draw really.
Extracting objects from an image, specially a picture is not that easy as you think, you may want to take a look at the OpenCV project.
OpenCV
Other than OpenCV, I would suggest looking at ITK. It is very popular in medical image analysis projects, because there it is known that semi-automatic segmentation tools provide the best results. I think that the methods apply to natural images as well.
Try looking at tools like livewire segmentation, and level-set based image segmentation. ITK has several demos that allow you to play with these tools on your own images. The demo application such as this is part of the open source distribution, but it can be downloaded directly from the itk servers (look around for instructions)
If this is a business case, you'd better look for companies specialized in "video content analysis". I mean it: reliable people and vehicle detection aren't a single man's project.
Genreral purpose segmentation tools won't do the trick because they have no notion of what a man or a car look like. All they are deemed to do is to find uniform regions in an image.
It is quite late but there is an algorithm called connected component labeling, which you may find useful.
here is wiki link of the algorithm
I am looking for an algorithm visualization library/tool that is well documented and you can call from your source code.
I took a look at jhave - example of usage. And I liked it, it seems it has some documentation but I do not trust its future.
I found this article about Algorithm explorer it has a nice idea. It is implemented as a c++ api but I cannot find it anywere.
My main idea is that I want to do some unit tests for the brain.
So I construct various exercises and in future when I want to test my knowledge I redo them.
I found that images stick longer with me, so that is why I want to visualize algorithms in certain states. ( I might remember better a tricky case like what happens when data is sorted in reverse and I use quick sort if I view it.)
An ideal tool:
1. Has to integrate with any language.
2. Has to be well documented with a growing comunity and examples.
3. Be implemented on top of a capable rendering engine(ogre, xna).
Here is the place you need to visit: The Algorithm Visualization Portal!
I have a friend that is starting up a new project. He wants to be able to use some sort of OCR in order to detect and translate Kanji symbols into other languages. He has hit a bit of a brick wall in finding available algorithms in order to do so, since these symbols are a bit more complex than the English characters that we're used to.
We suggested he start looking into 2D convolution and Fourier transforms to start the pattern recognition process, but he is looking for a good starting point.
Unfortunately my knowledge of OCR is extremely limited, so any suggestions that I can pass along will probably be most helpful!
Have a look at nhocr.
(Also, there is tesseract, but I'm not sure if they actually support CJK.)
There are quite a few questions with information about OCR on SO, for instance, try this search.
Is it possible to write a program that can extract a melody/beat/rhythm provided by a specific instument in a wave (or other music format) file made up of multiple instruments?
Which algorithms could be used for this and what programming language would be best suited to it?
This is a fascinating area. The basic mathematical tool here is the Fourier Transform. To get an idea of how it works, and how challenging it can be, take a look at the analysis of the opening chord to A Hard Day's Night.
An instrument produces a sound signature, just the same way our voices do. There are algorithms out there that can pick a single voice out of a crowd and identify that voice from its signature in a database which is used in forensics. In the exact same way, the sound signature of a single instrument can be picked out of a soundscape (such as your mixed wave) and be used to pick out a beat, or make a copy of that instrument on its own track.
Obviously if you're thinking about making copies of tracks, i.e. to break down the mixed wave into a single track per instrument you're going to be looking at a lot of work. My understanding is that because of the frequency overlaps of instruments, this isn't going to be straightforward by any means... not impossible though as you've already been told.
There's quite an interesting blog post by Comparisonics about sound matching technologies which might be useful as a start for your quest for information: http://www.comparisonics.com/SearchingForSounds.html
To extract the beat or rhythm, you might not need perfect isolation of the instrument you're targeting. A general solution may be hard, but if you're trying to solve it for a particular piece, it may be possible. Try implementing a band-pass filter and see if you can tune it to selects th instrument you're after.
Also, I just found this Mac product called PhotoSounder. They have a blog showing different ways it can be used, including isolating an individual instrument (with manual intervention).
Look into Karaoke machine algorithms. If they can remove voice from a song, I'm sure the same principles can be applied to extract a single instrument.
Most instruments make sound within certain frequency ranges.
If you write a tunable bandpass filter - a filter that only lets a certain frequency range through - it'll be about as close as you're likely to get. It will not be anywhere near perfect; you're asking for black magic. The only way to perfectly extract a single instrument from a track is to have an audio sample of the track without that instrument, and do a difference of the two waveforms.
C, C++, Java, C#, Python, Perl should all be able to do all of this with the right libraries. Which one is "best" depends on what you already know.
It's possible in principle, but very difficult - an open area of research, even. You may be interested in the project paper for Dancing Monkeys, a step generation program for StepMania. It does some fairly sophisticated beat detection and music analysis, which is detailed in the paper (linked near the bottom of that page).