edge-detection | 易学教程

Edge detection on C#

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问题 I have a black and white image like this (color overlays are mine, and can be removed): I need to figure out the edge of the hand shown, how can I do that? My current algorithm: List<Point> edgePoints = new List<Point>(); for (int x = 0; x < largest.Rectangle.Width && edgePoints.Count == 0; x++) { //top for (int y = 0; y < largest.Rectangle.Height - 3 && edgePoints.Count == 0; y++) { if (colorGrid[x, y].ToArgb() == Color.White.ToArgb() && colorGrid[x, y + 1].ToArgb() == Color.White.ToArgb() &

python laplace filter returns wrong values

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问题 As I need to implement a sort of image processing program in python I also wanted to implement the laplace filter. I used the matrix -1 -1 -1 -1 8 -1 -1 -1 -1 and implemented the following code: for row in range(1, (len(self._dataIn) - 1)): for col in range(1, (len(self._dataIn[row])- 1)): value = (- int(self._dataIn[row - 1][col -1][0]) - int(self._dataIn[row - 1][col][0]) - int(self._dataIn[row - 1][col + 1][0]) - int(self._dataIn[row][col -1][0]) + (8 * int(self._dataIn[row][col][0])) -

Sobel operator & Convolution with WriteableBitmapEx

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问题 So I'm using WriteableBitmapEx for an app on Windows RT. I'm trying to implement edge detection on an image using the sobel operator. I have successfully applied both kernels for x and y detection onto the image using .Convolute(), but now I'm stuck adding both images to one. The problem is, that all the pixels of both images seem to have the value 0 for transparency (so the A in ARGB). I can display both images on their own without a Problem, but adding them gives me just a black picture. So

Sub-Pixel Edge Detector Algorithm

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问题 I am working on edge detection, i tried the method of canny(matlab function). but it only detect edge in the pixel level, I'm looking for a subpixel edge detection algorithm/code with high accuracy. 回答1: AFAIK state-of-the-art edge detection algorithms operate at a pixel-level accuracy (e.g., gPb). If you want to get sub-pixel accuracy, you may apply a post-processing stage to the pixel-level results obtained by canny or gPb. You can fit a parametric curve to small neighborhoods of detected

Simple shape detection in a 1bpp image

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问题 I am trying to learn about simple shape detection for a project I'm working on. I have an image that is made of only black and white pixels and I need to detect shapes within the image, such as squares and ellipses. I also need to find the bounding boxes of the shapes. I have been searching online and reading articles but I can't find any good explanations of where to start. I am also looking for some partial/complete code examples preferably in Java or C++. Thanks! 回答1: There's a few

Get angle from OpenCV Canny edge detector

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问题 I want to use OpenCV's Canny edge detector, such as is outlined in this question. For example: cv::Canny(image,contours,10,350); However, I wish to not only get the final thresholded image out, but I also wish to get the detected edge angle at each pixel. Is this possible in OpenCV? 回答1: canny doesn't give you this directly. However, you can calculate the angle from the Sobel transform, which is used internally in canny() . Pseudo code: cv::Canny(image,contours,10,350); cv::Sobel(image, dx,

How to detect document from a picture in opencv?

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问题 I am trying to design an app similar to camscanner. For that, I have to take an image and then find the document in that. I started off with the code described here - http://opencvpython.blogspot.in/2012/06/sudoku-solver-part-2.html I found the contours and the rectangular contour with max area should be the required document. For every contour, I am finding an approximate closed PolyDP. Of all the polyDP of size 4, the one with max area should be the required document. However, this method

Line detection in image

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问题 I am new to image processing and I was trying to detect vertical lines using this code- image=imread('benzene.jpg'); BW = im2bw(image); w1=[-1 2 -1 ; -1 2 -1 ; -1 2 -1]; g=(imfilter(double(BW),w1)); g=abs(g); T=max(g(:)); g=g>=T; imshow(g); This was my image- And this is what I got after performming the operations- So my question is why am I getting this output?There are 10 vertical lines if vertical double bonds are counted as 2 distinct vertical lines.Also what if I want to get horizontal

Markerless AR lib for iPhone

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问题 I'm searching a functional AR Markerless library for the iPhone (from 3GS and supporting iOS 4.3 at least). I've already tested a large amount of SDKs including Qualcomm AR, Layar, ARToolkit, but none of them was satisfying my needs. To be more precise, I need neither a localization-based AR technology (Layar), nor a marker technology (ARToolkit). If possible, the library has to be free, as I don't have much financial resources. 回答1: Qualcomm ( QCAR ) has recently released an iOS version into

Sub-Pixel Edge Detector Algorithm

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I am working on edge detection, i tried the method of canny(matlab function). but it only detect edge in the pixel level, I'm looking for a subpixel edge detection algorithm/code with high accuracy. AFAIK state-of-the-art edge detection algorithms operate at a pixel-level accuracy (e.g., gPb ). If you want to get sub-pixel accuracy, you may apply a post-processing stage to the pixel-level results obtained by canny or gPb. You can fit a parametric curve to small neighborhoods of detected edges thus obtaining sub-pixel accuracy. The problem with running edge() on your original image is that the