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  • In a digital photo, detecting if a mountain is obscured by clouds.

    - by Gavin Brock
    The problem I have a collection of digital photos of a mountain in Japan. However the mountain is often obscured by clouds or fog. What techniques can I use to detect that the mountain is visible in the image? I am currently using Perl with the Imager module, but open to alternatives. All the images are taken from the exact same position - these are some samples. My naïve solution I started by taking several horizontal pixel samples of the mountain cone and comparing the brightness values to other samples from the sky. This worked well for differentiating good image 1 and bad image 2. However in the autumn it snowed and the mountain became brighter than the sky, like image 3, and my simple brightness test started to fail. Image 4 is an example of an edge case. I would classify this as a good image since some of the mountain is clearly visible.

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  • On-the-fly lossless image compression

    - by geschema
    I have an embedded application where an image scanner sends out a stream of 16-bit pixels that are later assembled to a grayscale image. As I need to both save this data locally and forward it to a network interface, I'd like to compress the data stream to reduce the required storage space and network bandwidth. Is there a simple algorithm that I can use to losslessly compress the pixel data? I first thought of computing the difference between two consecutive pixels and then encoding this difference with a Huffman code. Unfortunately, the pixels are unsigned 16-bit quantities so the difference can be anywhere in the range -65535 .. +65535 which leads to potentially huge codeword lengths. If a few really long codewords occur in a row, I'll run into buffer overflow problems.

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  • Shared value in parallel python

    - by Jonathan
    Hey all- I'm using ParallelPython to develop a performance-critical script. I'd like to share one value between the 8 processes running on the system. Please excuse the trivial example but this illustrates my question. def findMin(listOfElements): for el in listOfElements: if el < min: min = el import pp min = 0 myList = range(100000) job_server = pp.Server() f1 = job_server.submit(findMin, myList[0:25000]) f2 = job_server.submit(findMin, myList[25000:50000]) f3 = job_server.submit(findMin, myList[50000:75000]) f4 = job_server.submit(findMin, myList[75000:100000]) The pp docs don't seem to describe a way to share data across processes. Is it possible? If so, is there a standard locking mechanism (like in the threading module) to confirm that only one update is done at a time? l = Lock() if(el < min): l.acquire if(el < min): min = el l.release I understand I could keep a local min and compare the 4 in the main thread once returned, but by sharing the value I can do some better pruning of my BFS binary tree and potentially save a lot of loop iterations. Thanks- Jonathan

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  • Displaying Image On SmallBASIC

    - by Nathan Campos
    I want to display a image using SmallBASIC. For this I've started by searching on the references, then I found a reference for IMAGE, that is like this: IMAGE #handle, index, x, y [,sx,sy [,w,h]] Then I found another to open files(OPEN): OPEN file [FOR {INPUT|OUTPUT|APPEND}] AS #fileN But I want to know some things: What image types this function can display? There is any real example to use IMAGE?

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  • efficient algorithm for drawing circle arcs?

    - by banister
    I am using the mid-point circle algorithm (bresenham circle) to efficiently draw whole circles. Is there something similar to draw circle arcs? I would like to specify a start angle and end angle and have only that portion of the circle drawn. Thanks in advance! EDIT: I would like to draw filled circle arcs too, i.e pie-slices. :)

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  • Finding text orientation in image (angle for rotation)

    - by maximus
    There is an image captured by camera, and I need to find the angle of the text in order to rotate it to make the image better for OCR results. So I know that the fourier transform can be used for that purpose, My question is, does it really gives good results or may be it is better to use something different than that? Can you tell me if there is a good method for this purpose? I am afraid that not every image containing the text will give me a good result after using fourier transform method. Actually, if I make like it is written here: link text (see the part related with an example of text image) calculating the logarithm of the magnitude of the Fourier transform of image with text and then thresholding it, I get that points and I can calculate the line approximately passing through them, and after getting the line calculate the angle, and then make an affine transform, But, what if I do not get a good result every time using this method , and make a false transform? Any ideas please to judge wether the result is correct or not, or may be another method is better? The binary image can contain noise, even if there are not so much of them, the angle found as a result can be not accurate.

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  • pdf2swf using MAC OS Batch command or Apple script

    - by Garth Humphreys
    How do I write a batch process on the Mac for pdf2swf, I want to convert all pdfs in a folder into swf. But pdf2swf doesn't have a option to convert a folder of pdfs to swfs, you have to do it one at a time. I'm not sure how if I should use a Apple script or a Shell script, either one I'm not sure how to get or assign a file name variable. pdf2swf file_name_variable.pdf -o file_name_variable.swf -T 9 -f Thanks

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  • Overlay of multiple colors in ImageJ

    - by nico
    Hi everyone, I'm writing a little plugin for imageJ and I am drawing several regions as an overlay on the image. I'm using this code: ImagePlus imp = getImage(); Overlay ov = new Overlay(); for (int r=0; r<regions.length; r++) { ov.add(regions[r]); } imp.setOverlay(ov); Where regions is an array of Roi. This works as intended and draws the regions in the (hurting to my eyes) standard ImageJ cyan used for overlays. I would like to draw one particular region in another colour, but I cannot seem to find a way to do it. I found that you can change the colour of the whole overlay, but I need two colours in the same overlay. Any ideas? Thanks in advance nico

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  • How can I select the pixels from an image in opencv?

    - by ajith
    This is refined version of my previous question. Actually I want to do following operation... summation for all k|(i,j)?wk [(Ii-µk)*(Ij-µk)], where wk is a 3X3 window, µk is the mean of wk, Ii & Ij are the intensities of the image at i and j. I dont know how to select Ii & Ij separately from an image which is 2 dimensional[Iij]...or does the equation mean anything else?

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  • Regex for finding an unterminated string

    - by Austin Hyde
    I need to search for lines in a CSV file that end in an unterminated, double-quoted string. For example: 1,2,a,b,"dog","rabbit would match whereas 1,2,a,b,"dog","rabbit","cat bird" 1,2,a,b,"dog",rabbit would not. I have very limited experience with regular expressions, and the only thing I could think of is something like "[^"]*$ However, that matches the last quote to the end of the line. How would this be done?

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  • C# - Data Clustering approach

    - by Brett
    Hi all, I am writing a program in C# in which I have a set of 200 points displayed on an image. However, the points tend to cluster in various regions, and I am looking to find a way to "cluster." In other words, maybe draw a circle/ellipse around the clustered points. Has anyone seen any way to do this? I have heard about K-means clustering, but I am not sure how to implement it in C#. Any favorite implementations out there? Cheers, Brett

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  • How to isolate a single color in an image

    - by Janusz
    I'm using the python OpenCV bindings and at the moment I try to isolate a colorrange. That means I want to filter out everything that is not reddish. I tried to take only the red color channel but this includes the white spaces in the Image too. What is a good way to do that?

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  • algorithm for image comparison

    - by Rajnikant
    Please consider following use case, I have one bigger image, lets called is master image. Now from some where else, I am getting one small image. I want to check whether this small image is subset of master image or not. important points are, smaller image might have different file format, smaller image might captured from comparatively different view. smaller image may have different light intensity. At this stage of algorithm/computation advancement, which level of accuracy I could expect? Any algorithm/open source implementation that would have such implementation? Thanks, Rajnikant

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  • Why does Clojure hang after hacing performed my calculations?

    - by Thomas
    Hi all, I'm experimenting with filtering through elements in parallel. For each element, I need to perform a distance calculation to see if it is close enough to a target point. Never mind that data structures already exist for doing this, I'm just doing initial experiments for now. Anyway, I wanted to run some very basic experiments where I generate random vectors and filter them. Here's my implementation that does all of this (defn pfilter [pred coll] (map second (filter first (pmap (fn [item] [(pred item) item]) coll)))) (defn random-n-vector [n] (take n (repeatedly rand))) (defn distance [u v] (Math/sqrt (reduce + (map #(Math/pow (- %1 %2) 2) u v)))) (defn -main [& args] (let [[n-str vectors-str threshold-str] args n (Integer/parseInt n-str) vectors (Integer/parseInt vectors-str) threshold (Double/parseDouble threshold-str) random-vector (partial random-n-vector n) u (random-vector)] (time (println n vectors (count (pfilter (fn [v] (< (distance u v) threshold)) (take vectors (repeatedly random-vector)))))))) The code executes and returns what I expect, that is the parameter n (length of vectors), vectors (the number of vectors) and the number of vectors that are closer than a threshold to the target vector. What I don't understand is why the programs hangs for an additional minute before terminating. Here is the output of a run which demonstrates the error $ time lein run 10 100000 1.0 [null] 10 100000 12283 [null] "Elapsed time: 3300.856 msecs" real 1m6.336s user 0m7.204s sys 0m1.495s Any comments on how to filter in parallel in general are also more than welcome, as I haven't yet confirmed that pfilter actually works.

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  • Django Template tag, generating template block tag

    - by Issy
    Hi Guys, Currently a bit stuck, wondering if anyone can assist. I am using django-adminfiles. Which is a near little application. I want to use it to insert images into posts/articles/pages for a site i am building. How django-adminfiles works is it inserts a placeholder i.e <<< ImageFile and this gets rendered using a django template. It also has the feature of inserting custom options i.e (Insert Medium Image) , i figured i would used this to automatically resize images and include it in the post (similar to how WP does it). Django-adminfiles makes use of sorl.thumbnail app to generate thumbnails. So i have tried testing generating thumbnails: The current template that is used to render the inserted image is: {% spaceless %} <img src="{{ upload.upload.url }}" width="{{ upload.width }}" height="{{ upload.height }}" class="{{ options.class }}" class="{{ options.size }}" alt="{% if options.alt %}{{ options.alt }}{% else %}{{ upload.title }}{% endif %}" /> {% endspaceless %} I tried modifying this to: {% load thumbnail %} {% spaceless %} <img src="{% thumbnail upload.upload.url 200x50 %}" width="{{ upload.width }}" height="{{ upload.height }}" class="{{ options.class }}" class="{{ options.size }}" alt="{% if options.alt %}{{ options.alt }}{% else %}{{ upload.title }}{% endif %}" /> {% endspaceless %} I get the error: Exception Value: Caught an exception while rendering: Source file: '/media/uploads/DSC_0014.jpg' does not exist. I figured the thumbnail needs the absolute path so tried putting that in the template, and that works. i.e this works: {% thumbnail '/Users/me/media/uploads/DSC_0014.jpg' 200x50 %} So basically i need to generate the absolute path to the file give the relative path (to web root). You could do this by passing the MEDIA_ROOT setting to the template, but the reason i want to do a template tag is to programmatically set the image size.

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  • Spectral Reconstruction

    - by Hani
    I have a small system which consist of: Led Clusters, camera(RGB or grayscale) and an object to be detected. I am emitting a light from the LED clusters (ex: yellow). After emitting light on the object, I am capturing an image for the object from the camera. I want to get the spectral image of the object from the captured image. Please if any one knows the algorithm or a code for this purpose(grayscale or RGB camera), tell me. Thanks.....

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  • find the colour name from a hexadecimal colour code

    - by sree01
    Hi , i want to find the name of a colour from the hexadecimal colour code. When i get a hex colour code i want to find the most matching colour name. for example for the code #c06040 , how to find out if it is a shade of brown, blue or yellow ?. so that i can find the colour of an object in the image without human intervention. Is there any relation between the hexadecimal code of the shades of a colour? please give some sample code if there is any.

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  • Running Awk command on a cluster

    - by alex
    How do you execute a Unix shell command (awk script, a pipe etc) on a cluster in parallel (step 1) and collect the results back to a central node (step 2) Hadoop seems to be a huge overkill with its 600k LOC and its performance is terrible (takes minutes just to initialize the job) i don't need shared memory, or - something like MPI/openMP as i dont need to synchronize or share anything, don't need a distributed VM or anything as complex Google's SawZall seems to work only with Google proprietary MapReduce API some distributed shell packages i found failed to compile, but there must be a simple way to run a data-centric batch job on a cluster, something as close as possible to native OS, may be using unix RPC calls i liked rsync simplicity but it seem to update remote notes sequentially, and you cant use it for executing scripts as afar as i know switching to Plan 9 or some other network oriented OS looks like another overkill i'm looking for a simple, distributed way to run awk scripts or similar - as close as possible to data with a minimal initialization overhead, in a nothing-shared, nothing-synchronized fashion Thanks Alex

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