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  • How to mask part of an image in matlab ?

    - by ZaZu
    Hey guys, I would like to know how to mask part of an image that is in BLACK & WHITE ? I got an object that needs to be edge detected, but I have other white interfering objects in the background that are below the target objet ... I would like to mask the entire lower part of an image to black, how can I do that ? Thanks !!

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  • How to play extracted wave file byte array in C#?

    - by user261924
    At the moment i have managed to separate the left and right channel of a WAVE file and have included the header in a byte[] array. My next step is to be about to play both channels. How can this be done? Here is a code snippet: byte[] song_left = new byte[fa.Length]; byte[] song_right = new byte[fa.Length]; int p = 0; for (int c = 0; c < 43; c++) { song_left[p] = header[c]; p++; } int q = 0; for (s = startByte; s < length; s = s + 3) { song_left[s] = sLeft[q]; q++; s++; song_left[s] = sLeft[q]; q++; } p = 0; for (int c = 0; c < 43; c++) { song_right[p] = header[c]; p++; } This part is reading the header and data from both the right and light channel and saving it to array sLeft[] and sRight[]. This part is working perfectly. Once I obtained the byte arrays, I did the following: System.IO.File.WriteAllBytes("c:\\left.wav", song_left); System.IO.File.WriteAllBytes("c:\\right.wav", song_right); Added a button to play the saved wave file: private void button2_Click(object sender, EventArgs e) { spWave = new SoundPlayer("c:\\left.wav"); spWave.Play(); } Once I hit the play button, this error appers: An unhandled exception of type 'System.InvalidOperationException' occurred in System.dll Additional information: The wave header is corrupt. Any ideas?

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  • parallel computation for an Iterator of elements in Java

    - by Brian Harris
    I've had the same need a few times now and wanted to get other thoughts on the right way to structure a solution. The need is to perform some operation on many elements on many threads without needing to have all elements in memory at once, just the ones under computation. As in, Iterables.partition is insufficient because it brings all elements into memory up front. Expressing it in code, I want to write a BulkCalc2 that does the same thing as BulkCalc1, just in parallel. Below is sample code that illustrates my best attempt. I'm not satisfied because it's big and ugly, but it does seem to accomplish my goals of keeping threads highly utilized until the work is done, propagating any exceptions during computation, and not having more than numThreads instances of BigThing necessarily in memory at once. I'll accept the answer which meets the stated goals in the most concise way, whether it's a way to improve my BulkCalc2 or a completely different solution. interface BigThing { int getId(); String getString(); } class Calc { // somewhat expensive computation double calc(BigThing bigThing) { Random r = new Random(bigThing.getString().hashCode()); double d = 0; for (int i = 0; i < 100000; i++) { d += r.nextDouble(); } return d; } } class BulkCalc1 { final Calc calc; public BulkCalc1(Calc calc) { this.calc = calc; } public TreeMap<Integer, Double> calc(Iterator<BigThing> in) { TreeMap<Integer, Double> results = Maps.newTreeMap(); while (in.hasNext()) { BigThing o = in.next(); results.put(o.getId(), calc.calc(o)); } return results; } } class SafeIterator<T> { final Iterator<T> in; SafeIterator(Iterator<T> in) { this.in = in; } synchronized T nextOrNull() { if (in.hasNext()) { return in.next(); } return null; } } class BulkCalc2 { final Calc calc; final int numThreads; public BulkCalc2(Calc calc, int numThreads) { this.calc = calc; this.numThreads = numThreads; } public TreeMap<Integer, Double> calc(Iterator<BigThing> in) { ExecutorService e = Executors.newFixedThreadPool(numThreads); List<Future<?>> futures = Lists.newLinkedList(); final Map<Integer, Double> results = new MapMaker().concurrencyLevel(numThreads).makeMap(); final SafeIterator<BigThing> it = new SafeIterator<BigThing>(in); for (int i = 0; i < numThreads; i++) { futures.add(e.submit(new Runnable() { @Override public void run() { while (true) { BigThing o = it.nextOrNull(); if (o == null) { return; } results.put(o.getId(), calc.calc(o)); } } })); } e.shutdown(); for (Future<?> future : futures) { try { future.get(); } catch (InterruptedException ex) { // swallowing is OK } catch (ExecutionException ex) { throw Throwables.propagate(ex.getCause()); } } return new TreeMap<Integer, Double>(results); } }

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  • How to record sound from a microphone in VB6?

    - by Clay Nichols
    We've been recording sound for over a decade using what seems like a very clunky method using the Winmm.dll and the MCIsendString. I've read that this doesn't set the recording quality value correctly (not sure if that article was ever true or is still true). I was wondering if there is any better way to record sound.

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  • Rapid calls to fread crashes the application

    - by Slynk
    I'm writing a function to load a wave file and, in the process, split the data into 2 separate buffers if it's stereo. The program gets to i = 18 and crashes during the left channel fread pass. (You can ignore the couts, they are just there for debugging.) Maybe I should load the file in one pass and use memmove to fill the buffers? if(params.channels == 2){ params.leftChannelData = new unsigned char[params.dataSize/2]; params.rightChannelData = new unsigned char[params.dataSize/2]; bool isLeft = true; int offset = 0; const int stride = sizeof(BYTE) * (params.bitsPerSample/8); for(int i = 0; i < params.dataSize; i += stride) { std::cout << "i = " << i << " "; if(isLeft){ std::cout << "Before Left Channel, "; fread(params.leftChannelData+offset, sizeof(BYTE), stride, file + i); std::cout << "After Left Channel, "; } else{ std::cout << "Before Right Channel, "; fread(params.rightChannelData+offset, sizeof(BYTE), stride, file + i); std::cout << "After Right Channel, "; offset += stride; std::cout << "After offset incr.\n"; } isLeft != isLeft; } } else { params.leftChannelData = new unsigned char[params.dataSize]; fread(params.leftChannelData, sizeof(BYTE), params.dataSize, file); }

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  • minimum enclosing rectangle of fixed aspect ratio

    - by Ramya Narasimha
    I have an Image with many rectangles at different positions in the image and of different sizes (both overlapping and non-overlapping). I also have a non-negative scores associated with each of these rectangles. My problem now is to find one larger rectangle *of a fixed (given) aspect ratio* that encloses as many of these rectangles as possible. I am looking for an algorithm to do this, if anyone has a solution, even a partial one it would be helpful. Please note that the positions of the rectangles in the image is fixed and cannot be moved around and there is no orientation issue as all of them are upright.

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  • Detect Rotation of a scanned image in C#

    - by ahmed fouad
    We want a c# solution to correct the scanned image because it is rotated. To solve this problem we must detect the rotation angle first and then rotate the image. This was our first thought for our problem. But then we thought image warping would be more accurate as I think it would make the scanned image like our template. Then we can process it as we know all the coordinates of our template... I searched for a free SDK or a free solution in c#. Helping me in this will be great as it is the last task in our work. Really, thanks for all.

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  • Reading Character from Image

    - by Chinjoo
    I am working on an application which requires matching of numbers from a scanned image file to database entry and update the database with the match result. Say I have image- employee1.jpg. This image will have two two handwritten entries - Employee number and the amount to be paid to the employee. I have to read the employee number from the image and query the database for the that number, update the employee with the amount to be paid as got from the image. Both the employee number and amount to be paid are written inside two boxes at a specified place on the image. Is there any way to automate this. Basically I want a solution in .net using c#. I know this can be done using artificial neural networks. Any ideas would be much appreciated.

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  • Generate an image / thumbnail of a webpage using X/Gui-less linux

    - by dassouki
    There are a lot of solutions out there on generating a thumbnail or an image preview of a webpage. Some of these are websites like websnapshots, windows libraries such as PHP's imagegrabscreen (only works on windows), and KDE's wkhtml. Many more do exist. However, I'm looking for a GUI-less solution. Something I can create an API around and link it to php or python. I'm comfortable with python, php, C, and shell. This is a personal project, so I'm not interested in commercial applications as I'm aware of their existence. Any ideas?

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  • mean and variance of image in single pass

    - by ajith
    hi everyone,am trying to calculate mean and variance using 3X3 window over image(hXw) in opencv...here is my code...is there any accuracy issues with this??or is there any other efficient method to do it in one pass.? int pi,a,b; for(i=1;i

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  • How to start writing out an existing AudioQueue in response to an event?

    - by Halle
    Hello, I am writing a class that opens an AudioQueue and analyzes its characteristics, and then under certain conditions can begin or end writing out a file from that AudioQueue that is already instantiated. This is my code (entirely based on SpeakHere) that opens the AudioQueue without writing anything out to tmp: void AQRecorder::StartListen() { int i, bufferByteSize; UInt32 size; try { SetupAudioFormat(kAudioFormatLinearPCM); XThrowIfError(AudioQueueNewInput(&mRecordFormat, MyInputBufferHandler, this, NULL, NULL, 0, &mQueue), "AudioQueueNewInput failed"); mRecordPacket = 0; size = sizeof(mRecordFormat); XThrowIfError(AudioQueueGetProperty(mQueue, kAudioQueueProperty_StreamDescription, &mRecordFormat, &size), "couldn't get queue's format"); bufferByteSize = ComputeRecordBufferSize(&mRecordFormat, kBufferDurationSeconds); for (i = 0; i < kNumberRecordBuffers; ++i) { XThrowIfError(AudioQueueAllocateBuffer(mQueue, bufferByteSize, &mBuffers[i]), "AudioQueueAllocateBuffer failed"); XThrowIfError(AudioQueueEnqueueBuffer(mQueue, mBuffers[i], 0, NULL), "AudioQueueEnqueueBuffer failed"); } mIsRunning = true; XThrowIfError(AudioQueueStart(mQueue, NULL), "AudioQueueStart failed"); } catch (CAXException &e) { char buf[256]; fprintf(stderr, "Error: %s (%s)\n", e.mOperation, e.FormatError(buf)); } catch (...) { fprintf(stderr, "An unknown error occurred\n"); } } But I'm a little unclear on how to write a function that will tell this queue "from now until the stop signal, start writing out this queue to tmp as a file". I understand how to tell an AudioQueue to write out as a file at the time that it's created, how to set files format, etc, but not how to tell it to start and stop midstream. Much appreciative of any pointers, thanks.

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  • Who do you use for a merchant account?

    - by Josh
    Hi everyone, I was hoping to get an idea of the merchant accounts out there and if there are any strong recommendations for one in particular. I would also appreciate advice on how merchant accounts differ. Please use separate answers for each recommendation so that we can take full advantage of the voting system. Thanks!

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  • Finding a small image in a bigger one

    - by tur1ng
    Given an image with a large dimension ( 1.000 x 1.000). What is a good approach to find a small image (e.g. 50 x 50) in the big one? The smaller image can be rotated and differ in the size, but only with a 1:1 ratio. It's not related to any programming language - I'm just interested in pattern recognition. Thank you.

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  • filter that uses elements from two arrays at the same time

    - by Gacek
    Let's assume we have two arrays of the same size - A and B. Now, we need a filter that, for a given mask size, selects elements from A, but removes the central element of the mask, and inserts there corresponding element from B. So the 3x3 "pseudo mask" will look similar to this: A A A A B A A A A Doing something like this for averaging filter is quite simple. We can compute the mean value for elements from A without the central element, and then combine it with a proper proportion with elements from B: h = ones(3,3); h(2,2) =0; h = h/sum(h(:)); A_ave = filter2(h, A); C = (8/9) * A_ave + (1/9) * B; But how to do something similar for median filter (medfilt2 or even better for ordfilt2)

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  • Java: Line appears when using AffineTransform to scale image

    - by Malakim
    Hi, I'm having a problem with image scaling. When I use the following code to scale an image it ends up with a line either at the bottom or on the right side of the image. double scale = 1; if (scaleHeight >= scaleWidth) { scale = scaleWidth; } else { scale = scaleHeight; } AffineTransform af = new AffineTransform(); af.scale(scale, scale); AffineTransformOp operation = new AffineTransformOp(af, AffineTransformOp.TYPE_NEAREST_NEIGHBOR); BufferedImage bufferedThumb = operation.filter(img, null); The original image is here: http://tinyurl.com/yzv6r7h The scaled image: http://tinyurl.com/yk6e8ga Does anyone know why the line appears? Thanks!

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  • How to solve the problem of not being informed of successful payments by the 3rd party system used b

    - by user68759
    I have a subscription based website that interacts with a 3rd party system to handle the payments. The steps to process a new subscriber registration are as follow: The subscriber enters his/her details in the subscription form and click on the submit button. Assuming the details specified are valid, a new record is created in the database to store these details. The subscriber is then redirected to the website of the 3rd party system (similar to paypal) to process the payment. Once the payment is succesful, the 3rd party website then redirect the subscriber back to our website. At this time, I know that the payment was succesful, so the record in the database is updated to indicate that payment has been made successfully. A problem that I have found occurring quite often is that if a subscriber pays but does not complete the process correctly (e.g. uses the back browser, closes the window), his/her record in the database doesn't get updated about this. Accordingly, I don't know if s/he has paid by just looking the record and need to wait for the report from the 3rd party system to find this out. How do you solve this problem? PS. One of the main reasons to store their details into the database before the payment process is done is so they can come back to complete the payment without re-entering their details again. For example, when their credit cards were rejected by the 3rd party system and they need to sort this out with their financial institution which may take a while.

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  • What exactly does raw microphone data represent?

    - by esperantist
    I'm using PyAudio, a PortAudio wrapper for Python. I'm getting data from a microphone. Data which is represented by a continuous stream of bytes divided into chunks (of a size determined by me). I've tried to plot the signal, assuming the bytes represent the current signal amplitude, but I get an interesting image that I can't easily describe. ^^ It seems to be composed of two waves, one shifted from the other. What exactly do the particular bytes represent, and how does this change when I'm recording only one channel, instead of two? Any explanations, suggestions, code snippets, anything, very welcome! (I'm new at this.) Thanks!

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  • What is the "task" in twitter Storm parallelism

    - by John Wang
    I'm trying to learn twitter storm by following the great article "Understanding the parallelism of a Storm topology" However I'm a bit confused by the concept of "task". Is a task an running instance of the component(spout or bolt) ? A executor having multiple tasks actually is saying the same component is executed for multiple times by the executor, am I correct ? Moreover in a general parallelism sense, Storm will spawn a dedicated thread(executor) for a spout or bolt, but what is contributed to the parallelism by an executor(thread) having multiple tasks ? I think having multiple tasks in a thread, since a thread executes sequentially, only make the thread a kind of "cached" resource, which avoids spawning new thread for next task run. Am I correct? I may clear those confusion by myself after taking more time to investigate, but you know, we both love stackoverflow ;-) Thanks in advance.

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