First, check out /samples/c/squares.c in your OpenCV distribution. This example provides a square detector, and it should be a pretty good start on how to detect corner-like features. Then, take a look at OpenCV’s feature-oriented functions like cvCornerHarris() and cvGoodFeaturesToTrack(). The above methods can return many corner-like features – most will not be the “true … Read more
This is how I am getting a color from an image at a touch location. I translated this answer: https://stackoverflow.com/a/12579413/359578 (This sample does no error checking for nil) func createARGBBitmapContext(inImage: CGImage) -> CGContext { var bitmapByteCount = 0 var bitmapBytesPerRow = 0 //Get image width, height let pixelsWide = CGImageGetWidth(inImage) let pixelsHigh = CGImageGetHeight(inImage) // … Read more
I wrote a very simple python code to read YUV NV21 stream from binary file. import cv2 import numpy as np class VideoCaptureYUV: def __init__(self, filename, size): self.height, self.width = size self.frame_len = self.width * self.height * 3 / 2 self.f = open(filename, ‘rb’) self.shape = (int(self.height*1.5), self.width) def read_raw(self): try: raw = self.f.read(self.frame_len) yuv … Read more
You may want to check out the answers to these similar question: Image processing language/environment
You can view compress level using the identify tool in ImageMagick. Download and installation instructions can be found at the official website. After you install it, run the following command from the command line: identify -format ‘%Q’ yourimage.jpg This will return a value from 0 (low quality, small filesize) to 100 (high quality, large filesize). … Read more
As you don’t care if it is a vector shape or a bitmap, I’ll just outline solutions using a bitmap here. If you actually wanted a vector shape, I believe you would need to work with vector input to get a good result. Use a ColorAdjust effect with the brightness set to minimum (-1). Cache … Read more
Please check some thinning implementations in my blog: Zhang-Suen algorithm. (copy on archive.org) Guo-Hall algorithm. (copy on archive.org) Both using OpenCV 2.x API.
Motion blur and camera shake are kind of the same thing when you think about the cause: relative motion of the camera and the object. You mention slow shutter speed — it is a culprit in both cases. Focus misses are subjective as they depend on the intent on the photographer. Without knowing what the … Read more
Complete solution for arbitrary Sobel kernel sizes and angles tl;dr: skip down to section ‘Examples’ To add another solution, expanding on this document (it’s not particularly high quality, but it shows some usable graphics and matrices starting at the bottom of page 2). Goal What we’re trying to do is estimate the local gradient of … Read more
Comparing histograms is quite a subject in itself. You’ve got two big classes of comparison functions : bin-to-bin comparison and cross-bin comparison. Bin-to-bin comparison : As you stated, standard sum of differences is quite bad. There’s an improvement: the Chi-squared distance. If H1.red[0] = 0.001 and H2.red[0] = 0.011, then H2.red[0] is much more important … Read more