I have a video of a set of blinking lights(LED in different frequencies) over a dark background and I want to detect LED , then track them in the video.
How can I do it if the number of LED is not given ?
I would suggest colour tracking from a video, try this link. There is example code and an explanation to how this is achieved in openCV.
The code is written in python, but once you have an idea of how it works, porting it to C++ shouldnt be too hard (Or you could do it in Python)
I think if you would like a more in-depth answer you should try providing more information in your question, it is rather vague. Explain more about what you are trying to achieve as an end goal, and hopefully people will be able to give you better information.
Related
See the picture below. It's a flash game from a well known website :)
http://imageshack.us/photo/my-images/837/poolu.jpg/
I'd like to capture the images, frame by frame, using Matlab, and then lenghten the line that goes from the 8 ball, the short one, so i can see exactly where it will go. And display another window, in which the exact pool table will appear but with longer lines for the paths :)
I know, or can easily find out, how to capture the screen and whatnot, the problem is that i'm not sure how to start detecting those lines, to see the direction they are heading towards. Can anyone suggest an idea on how to accomplish this? Any image processing techniques i could use to at least filter out everything except those lines.
Not sure where to even start looking, or for WHAT.
And yeah, it's a cheat i know. But i got programming skills, why not put them in practice? :D Help me out people, it's a fun project :)
Thanks.
I would try using the Hough transform in the Matlab Image Processing Toolbox.
EDIT1:
Basically the Hough transform is a technique for detecting linear structures (lines) in an image.
I'm a noob to this forum, but wanted to give it a try.
I'm currently learning Objective-C and Cocoa; trying to build my first iPhone app.
One thing I'm working on is allowing the user to cut his/her face from an image they have taken and paste it into another image. (The idea is cut from one image and paste into another image with a spot for a face to go.)
How can this be done? I am thinking I would allow the user to just touch and drag over their face, in the shape of a rectangle, and then allow them to copy.
Thanks for the help.
Ok, nevertheless your bit arrogant style of asking, here are some guidelines about how to start: generic obj-c/iOS development (start from hello world); UIImage class; camera API; image processing algorithms, face detection algorithms. Go on gradually and do not wish to resolve all problems at once. Write first an application that simple loads an arbitrary photo and shows it to the user. Then modify it that you can crop a specified rectangular area from the image and save it into the new file. Then write an app that switches on the camera that you can take an image and save it to the disk. Then unite what you wrote that you save only a cropped area of the captured image.
When you arrive to this point, you will know much more about software development image handling. AFTER THIS you can start looking for image processing algorithms. Start also here with something simple like a trivial blur filter or similar implemented by you. If you know already a bit of image processing, search for face detection algorithms on the net. It is even possible that you will find some ready framework that includes also these features, or at least you will understand the concepts. You can even come back here to stack overflow and ask for suggestions about a good face detection algorithms, however we still prefer if you have chosen already one and have some concrete issue with it.
I have to implement long exposure photo capabilities to an app. Since i know that this is not really possible i have to fake it. It should work like "Slow Shutter" or "Magic Shutter".
Sadly i got no clue how to achieve this. I know how to take images with the camera (through AVFoundation) but i'm stuck at merging them to fake long shutter times.
Possibly i need to manipulate and combine all the images with coregraphics but i'm not sure about this (even the how). Maybe there's a better solution to this.
I would appreciate every help i can get here,
thank you people!
You might try the plus lighter blend mode.
Well, I suppose it would be possible to average together the results of several shots. I've mucked around a bit with the core graphics stuff to resize images (averaging together adjacent pixels), but with lower res images. The algorithm I used is here -- maybe it'll give you some ideas.
There may, of course, be a better way, and some tricks for working efficiently with high-res images. Can't help you there.
Convert the images to pixel bitmaps. Align and stack the bitmaps. Then try applying various 3D convolution filters to the 3D pixel array.
I'm currently trying to write an app, that would be able to show the effects of glas, as seen through the iPhone Camera.
I'm not talking about simple, uniform glas but glass like this:
Now I already broke this into two problems:
1) Apply some Image Filter to the 2D-frames presented by the iPhone Camera. This has been done and seems possible, e.g. in the app: faceman
2) I need to get the individual lighting properties of a sheet of glas that my client supplies me with. Now basicly, there must be a way to read the information about how the glas distorts ands skews the image. I think It might be somehow possible to make a high-res picture of the plate of glasplate, laid on a checkerboard-image and somehow analyze this.
Now, I'm mostly searching for literature, weblinks on how you guys think I could start at 2. It doesn't need to be exact, in the end I just need something that looks approximately like the sheet of glass I want to show. And I'm don't even know where to search, Physics, Image Filtering or Comupational Photography books.
EDIT: I'm currently thinking, that one easy solution could be bump-mapping the texture on top of the camera-feed, I asked another question on this here.
You need to start with OpenGL. You want to effectively have a texture - similar to the one you've got above - displace the texture below it (the live camera view) to give the impression of depth and distortion. This is a 'non-trivial' problem, in that whilst it's a fairly standard problem in its field if you're coming from a background with no graphics or OpenGL experience you can expect a very steep learning curve.
So in short, the only way you can achieve this realistically on iOS is to use OpenGL, and that should be your starting point. Apple have a few guides on the matter, but you'll be better off looking elsewhere. There are some useful books such as the OpenGL ES 2.0 Programming Guide that can get you off on the right track, but where you start would depend on how comfortable you are with 3D graphics and C.
Just wanted to add that I solved this old answer using the refraction example in the Khronos OpenGl ES SDK.
Wrote a blog-entry with pictures about it :
simulating windows with refraction
I'm trying to write a game where the user can issue commands by drawing certain patterns with his fingers..for example, if he draws a circle, an 'S' letter, an expiral, etc.
I'm already familiar with touch events and I'm capable of reading the coordinates... my problem Is in finding algorithms and information about the recognition of the patterns with some degree of error.... for example, If I'm supposed to detect a circle I should detect it even if the user didn't did a make perfect one.
Any resources in the matter?, thanks !
This site demos a very simple, easy to implement gesture recognizer, which they wrote in Javascript. I've implemented it myself in another language, and found it quite easy to deal with. They've got code, and a paper describing the algorithm; everything you could need.
The patterns you're referring to are known as "gestures".
This code seems to be what you're looking for.