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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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  • PHP Thumbnail image generator works, but consistently awaits 90% of its loadtime! Why?

    - by Sam
    Hi folks, This is the follow-up question from this general page load speed question. This question which will focus only, entirely and specifically on the thumbnail generator PHP code with the question: What's causing the 97% delays on these tiny thumbnails? Measuring only 3 ~ 5 kb each, this is strange indeed! Even after 7 orso bounty-rounds and 100 upvotes, the images are still doing nothing for over 97% of the time. It works allright, but it could be so much faster! ZAM, my pet robot, was so annoyed by not knowing why, he just pulled out some cords! Silly metal box... (I have asked permission from the original author, to put temporarily segments of the code online that I think could be the problem, after which I will remove all code, except the several lines that were the direct cause of this issue here to match the answer. This will be the free opportunity to perfect/speedup his otherwise already to my opinion vert versatile and userfriendly thumbnail generator.)

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  • Resize an array of images with OpenCV

    - by amr
    I'm passing an array of images (IplImage**) to an object in C++ using OpenCV. I'm then trying to iterate over that array and resize them all to a fixed size (150x150) I'm doing it this way: for(int i = 0; i< this->numTrainingFaces; i++) { IplImage* frame_copy = cvCreateImage( cvSize(150,150), this->faceImageArray[0]->depth, this->faceImageArray[0]->nChannels ); cout << "Created image" << endl; cvResize(this->faceImageArray[i], frame_copy); cout << "Resized image" << endl; IplImage* grey_image = cvCreateImage( cvSize( frame_copy->width, frame_copy->height ), IPL_DEPTH_8U, 1 ); cout << "Created grey image" << endl; cvCvtColor( frame_copy, grey_image, CV_RGB2GRAY ); cout << "Converted image" << endl; this->faceImageArray[i] = grey_image; cvReleaseImage(&frame_copy); cvReleaseImage(&grey_image); } But I'm getting this output, and I'm not sure why: Created image Resized image Created grey image Converted image Created image OpenCV Error: Assertion failed (src.type() == dst.type()) in cvResize, file /build/buildd/opencv-2.1.0/src/cv/cvimgwarp.cpp, line 3102 terminate called after throwing an instance of 'cv::Exception' what(): /build/buildd/opencv-2.1.0/src/cv/cvimgwarp.cpp:3102: error: (-215) src.type() == dst.type() in function cvResize Aborted I'm basically just trying to replace the image in the array with the resized one in as few steps as possible. Edit: Revised my code as follows: for(int i = 0; i< this->numTrainingFaces; i++) { IplImage* frame_copy = cvCreateImage( cvSize(150,150), this->faceImageArray[i]->depth, this->faceImageArray[i]->nChannels ); cvResize(this->faceImageArray[i], frame_copy); IplImage* grey_image = cvCreateImage( cvSize( frame_copy->width, frame_copy->height ), IPL_DEPTH_8U, 1 ); cvCvtColor( frame_copy, grey_image, CV_RGB2GRAY ); faceImageArray[i] = cvCreateImage( cvSize(grey_image->width, grey_image->height), grey_image->depth, grey_image->nChannels); cvCopy(grey_image,faceImageArray[i]); cvReleaseImage(&frame_copy); cvReleaseImage(&grey_image); } Then later on I'm performing some PCA, and get this output: OpenCV Error: Null pointer (Null pointer to the written object) in cvWrite, file /build/buildd/opencv-2.1.0/src/cxcore/cxpersistence.cpp, line 4740 But I don't think my code has got to the point where I'm explicitly calling cvWrite, so it must be part of the library. I can give a full implementation if necessary - is there anything in my code that's going to create a null pointer?

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  • problem with background subtraction

    - by riyana
    I'm doing background subtraction using opencv. The problem is the foreground object is not always detected correctly. To deal with this I would like to use four or five images, and take their average as the background image. How can I do that?

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  • detect sender of signal (linux, ptrace)

    - by osgx
    Hello Can I distinguish signal, between delivered directly to a process and delivered via debugger. Case 1: $ ./process1 process1 (not ptraced) set up handler alarm(5); .... signal is handled and I can parse handler parameters Case 2: $ debugger1 ./process1 process1 (is ptraced by debugger1) set up handler alarm(5); ... signal is catched by debugger1. It resumes process1 with PTRACE_CONT, signal_number is 4th parameter of PTRACE_CONT. signal is redelivered to process1 it is handled. So, how can I detect in signal handler, was it redelivered by debugger or send by system? OS is Linux, kernel is 2.6.30. Programs are written in plain C.

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  • Fastest way to compute a "Visual" checksum of an image

    - by ensnare
    I'm looking to create an ID system for cataloging images. I can't use md5() since that will change if I alter the EXIF tags of the image. I am currently using the SHA1 checksum computed by imagemagick. It works perfectly, but it's really, really slow on larger images (~15 seconds on a quad-core xeon for a 21 megapixel JPG). Are there any other "visual" methods of uniquely identifying an image that would be faster? Thank you.

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  • Java text classification problem

    - by yox
    Hello, I have a set of Books objects, classs Book is defined as following : Class Book{ String title; ArrayList<tags> taglist; } Where title is the title of the book, example : Javascript for dummies. and taglist is a list of tags for our example : Javascript, jquery, "web dev", .. As I said a have a set of books talking about different things : IT, BIOLOGY, HISTORY, ... Each book has a title and a set of tags describing it.. I have to classify automaticaly those books into separated sets by topic, example : IT BOOKS : Java for dummies Javascript for dummies Learn flash in 30 days C++ programming HISTORY BOOKS : World wars America in 1960 Martin luther king's life BIOLOGY BOOKS : .... Do you guys know a classification algorithm/method to apply for that kind of problems ? A solution is to use an external API to define the category of the text, but the problem here is that books are in different languages : french, spanish, english ..

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  • Baffled by differences between WPF BitmapEncoders

    - by DanM
    I wrote a little utility class that saves BitmapSource objects to image files. The image files can be either bmp, jpeg, or png. Here is the code: public class BitmapProcessor { public void SaveAsBmp(BitmapSource bitmapSource, string path) { Save(bitmapSource, path, new BmpBitmapEncoder()); } public void SaveAsJpg(BitmapSource bitmapSource, string path) { Save(bitmapSource, path, new JpegBitmapEncoder()); } public void SaveAsPng(BitmapSource bitmapSource, string path) { Save(bitmapSource, path, new PngBitmapEncoder()); } private void Save(BitmapSource bitmapSource, string path, BitmapEncoder encoder) { using (var stream = new FileStream(path, FileMode.Create)) { encoder.Frames.Add(BitmapFrame.Create(bitmapSource)); encoder.Save(stream); } } } Each of the three Save methods work, but I get unexpected results with bmp and jpeg. Png is the only format that produces an exact reproduction of what I see if I show the BitmapSource on screen using a WPF Image control. Here are the results: BMP - too dark JPEG - too saturated PNG - correct Why am I getting completely different results for different file types? I should note that the BitmapSource in my example uses an alpha value of 0.1 (which is why it appears very desaturated), but it should be possible to show the resulting colors in any image format. I know if I take a screen capture using something like HyperSnap, it will look correct regardless of what file type I save to. Here's a HyperSnap screen capture saved as a bmp: As you can see, this isn't a problem, so there's definitely something strange about WPF's image encoders. Do I have a setting wrong? Am I missing something?

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  • Stack usage with MMX intrinsics and Microsoft C++

    - by arik-funke
    I have an inline assembler loop that cumulatively adds elements from an int32 data array with MMX instructions. In particular, it uses the fact that the MMX registers can accommodate 16 int32s to calculate 16 different cumulative sums in parallel. I would now like to convert this piece of code to MMX intrinsics but I am afraid that I will suffer a performance penalty because one cannot explicitly intruct the compiler to use the 8 MMX registers to accomulate 16 independent sums. Can anybody comment on this and maybe propose a solution on how to convert the piece of code below to use intrinsics? == inline assembler (only part within the loop) == paddd mm0, [esi+edx+8*0] ; add first & second pair of int32 elements paddd mm1, [esi+edx+8*1] ; add third & fourth pair of int32 elements ... paddd mm2, [esi+edx+8*2] paddd mm3, [esi+edx+8*3] paddd mm4, [esi+edx+8*4] paddd mm5, [esi+edx+8*5] paddd mm6, [esi+edx+8*6] paddd mm7, [esi+edx+8*7] ; add 15th & 16th pair of int32 elements esi points to the beginning of the data array edx provides the offset in the data array for the current loop iteration the data array is arranged such that the elements for the 16 independent sums are interleaved.

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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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  • 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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  • 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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  • Why does this code read all ' ' for the anything after the 4th character?

    - by djs22
    #define fileSize 100000 int main(int argc, char *argv[]){ char *name=argv[1]; char ret[fileSize]; FILE *fl = fopen(name, "rb"); fseek(fl, 0, SEEK_END); long len = fileSize; fseek(fl, 0, SEEK_SET); //fread(ret, 1, len, fl); int i; *(ret+fileSize) = '\0'; for (i=0; i<fileSize; i++){ *(ret+i)=fgetc(fl); printf("byte : %s \n", ret); } fclose(fl); } In the above code, when I feed the name of a jpeg file, it reads anything after the 4th character as ' '...any ideas? Thanks!

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  • Resizing Images with ASP.NET and saving to Database

    - by Ryan
    I need to take an uploaded image, resize it, and save it to the database. Simple enough, except I don't have access to save any temp files to the server. I'm taking the image, resizing it as a Bitmap, and need to save it to a database field as the original image type (JPG for example). How can I get the FileBytes() like this, so I can save it to the database? Before I was using ImageUpload.FileBytes() but now that I'm resizing I'm dealing with Images and Bitmaps instead of FileUploads and can't seem find anything that will give me the bytes. Thanks!

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  • How would I detect horizontal-black lines using ImageMagick?

    - by Zando
    So I have what is essentially a spreadsheet in TIFF format. There is some uniformity to it...for example, all the column widths are the same. I want to de-limit this sheet by those known-column widths and basically create lots of little graphic files, one for each cell, and run OCR on them and store it into a database. The problem is that the horizontal lines are not all the same height, so I need to use some kind of graphics library command to check if every pixel across is the same color (i.e. black). And if so, then I know I've reached the height-delimiter for a cell. How would I go about doing that? (I'm using RMagick)

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  • Improving Performance on this Image Creation function

    - by Abs
    Hello all, I am making use of GD2 and the image functions to take in a string and then convert that into an image using different fonts at different sizes. The function I use is below. Currently, its pretty quick but not quick enough. The function gets called about 20 times per user and the images generated are always new ones (different) so caching isn't going to help! I was hoping to get some ideas on how to make this function faster. Maybe supply more RAM to the script running? Anything else that is specific to this PHP function? Anything else that I can do to tweak performance of this function? function generate_image($save_path, $text, $font_path, $font_size){ $font = $font_path; /* * I have simplifed the line below, its actually a function that works out the size of the box * that is need for each image as the image size is different based on font type, font size etc */ $measure = array('width' => 300, 'height'=> 120); if($measure['width'] > 900){ $measure['width'] = 900; } $im = imagecreatetruecolor($measure['width'], $measure['height']); $white = imagecolorallocate($im, 255, 255, 255); $black = imagecolorallocate($im, 0, 0, 0); imagefilledrectangle($im, 0, 0, $measure['width'], $measure['height'], $white); imagettftext($im, $font_size, 0, $measure['left'], $measure['top'], $black, $font, ' '.$text); if(imagepng($im, $save_path)){ $status = true; }else{ $status = false; } imagedestroy($im); return $status; } Thanks all for any help

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  • Image Resizing: Poor jpeg quality and black PNG backgrounds

    - by azz0r
    Hello, I have two issues with my class, basically the quality of the jpeg images is quite poor, but I'm not sure if thats down to my ratio resizing. Ideally I'd like this class to be strict with image sizes and crop into them, but I cant get my head around it. My main issue is that pngs always have a black bg, does anyone have experience with this happening? <?php class OpenSource_ImageResize { function __construct($theFile, $toWhere, $mime, $extension, $newWidth, $newHeight) { if ($mime == NULL) { $mime = getimagesize($theFile); $mime = $mime['mime']; } if ($mime == 'image/jpeg') { $size = getimagesize($theFile); if ($size[0] > $newWidth || $size[1] > $newHeight) { $sourceImage = imagecreatefromjpeg($theFile); } else { return copy($theFile, $toWhere); throw new exception('Could not create jpeg'); return false; } } else if ($mime == 'image/png') { $size = getimagesize($theFile); if ($size[0] > $newWidth || $size[1] > $newHeight) { $sourceImage = imagecreatefrompng($theFile); } else { return copy($theFile, $toWhere); //throw new exception('Could not create png'); return false; } } else if ($mime == 'image/gif') { $size = getimagesize($theFile); if ($size[0] > $newWidth || $size[1] > $newHeight) { $sourceImage = imagecreatefromgif ($theFile); } else { return copy($theFile, $toWhere); //throw new exception('Could not create gif'); return false; } } else { throw new exception('Not a valid mime type'); return false; } $oldX = imageSX($sourceImage); $oldY = imageSY($sourceImage); if ($newWidth == NULL) { $thumbHeight = $newHeight; $thumbWidth = round($newHeight/($oldY/$oldX)); } else if ($oldX > $oldY) { $thumbWidth = $newWidth; $thumbHeight = $oldY * ($newHeight/$oldX); } if ($oldX < $oldY) { $thumbWidth = round($newHeight/($oldY/$oldX)); $thumbHeight = $newHeight; } if ($oldX == $oldY) { $thumbWidth = $newWidth; $thumbHeight = $newHeight; } if (!gd_info()) { $dstImage = ImageCreate($thumbWidth, $thumbHeight); imagecopyresized($dstImage, $sourceImage, 0, 0, 0, 0, $thumbWidth, $thumbHeight, $oldX, $oldY); } else { $dstImage = ImageCreateTrueColor($thumbWidth, $thumbHeight); imagecopyresampled($dstImage, $sourceImage, 0, 0, 0, 0, $thumbWidth, $thumbHeight, $oldX, $oldY); } if ($mime == 'image/png') { $xparent = imagecolorresolvealpha($dstImage, 255,2,240, 0) ; imagecolortransparent($dstImage,$xparent); imagealphablending($dstImage,true); imagepng($dstImage, $toWhere); } else if ($mime == 'image/jpeg') { imagejpeg($dstImage, $toWhere); } else if ($mime == 'image/gif') { imagegif ($dstImage, $toWhere); } imagedestroy($dstImage); imagedestroy($sourceImage); return true; } }

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  • Removing the transperancy from image while keeping the actual image

    - by KPL
    Hello people, I have three images,and , they are not square or rectangular in shape. They are just like face of anyone. So,basically, my images are in the size 196x196 or anything like that, but complete square or rectangle with the face in the middle and transperant background in the rest of the portion. Now, I want to remove the transperant background too and just keep the faces. Don't know if this is possible and mind you, this isn't a programming question.

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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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  • 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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  • Technique to remove common words(and their plural versions) from a string

    - by Jake M
    I am attempting to find tags(keywords) for a recipe by parsing a long string of text. The text contains the recipe ingredients, directions and a short blurb. What do you think would be the most efficient way to remove common words from the tag list? By common words, I mean words like: 'the', 'at', 'there', 'their' etc. I have 2 methodologies I can use, which do you think is more efficient in terms of speed and do you know of a more efficient way I could do this? Methodology 1: - Determine the number of times each word occurs(using the library Collections) - Have a list of common words and remove all 'Common Words' from the Collection object by attempting to delete that key from the Collection object if it exists. - Therefore the speed will be determined by the length of the variable delims import collections from Counter delim = ['there','there\'s','theres','they','they\'re'] # the above will end up being a really long list! word_freq = Counter(recipe_str.lower().split()) for delim in set(delims): del word_freq[delim] return freq.most_common() Methodology 2: - For common words that can be plural, look at each word in the recipe string, and check if it partially contains the non-plural version of a common word. Eg; For the string "There's a test" check each word to see if it contains "there" and delete it if it does. delim = ['this','at','them'] # words that cant be plural partial_delim = ['there','they',] # words that could occur in many forms word_freq = Counter(recipe_str.lower().split()) for delim in set(delims): del word_freq[delim] # really slow for delim in set(partial_delims): for word in word_freq: if word.find(delim) != -1: del word_freq[delim] return freq.most_common()

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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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