Tracking white color using python opencv

Let’s take a look at HSV color space: You need white, which is close to the center and rather high. Start with sensitivity = 15 lower_white = np.array([0,0,255-sensitivity]) upper_white = np.array([255,sensitivity,255]) and then adjust the threshold to your needs. You might also consider using HSL color space, which stands for Hue, Saturation, Lightness. Then you … Read more

How to use SIFT algorithm to compute how similar two images are?

First, aren’t you supposed to be using vl_sift instead of sift? Second, you can use SIFT feature matching to find correspondences in the two images. Here’s some sample code: I = imread(‘p1.jpg’); J = imread(‘p2.jpg’); I = single(rgb2gray(I)); % Conversion to single is recommended J = single(rgb2gray(J)); % in the documentation [F1 D1] = vl_sift(I); … Read more

Calculating percentage of Bounding box overlap, for image detector evaluation

For axis-aligned bounding boxes it is relatively simple. “Axis-aligned” means that the bounding box isn’t rotated; or in other words that the boxes lines are parallel to the axes. Here’s how to calculate the IoU of two axis-aligned bounding boxes. def get_iou(bb1, bb2): “”” Calculate the Intersection over Union (IoU) of two bounding boxes. Parameters … Read more

How to recognize vehicle license / number plate (ANPR) from an image? [closed]

EDIT: I wrote a Python script for this. As your objective is blurring (for privacy protection), you basically need a high recall detector as a first step. Here’s how to go about doing this. The included code hints use OpenCV with Python. Convert to Grayscale. Apply Gaussian Blur. img = cv2.imread(‘input.jpg’,1) img_gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) … Read more

Fit Quadrilateral (Tetragon) to a blob

I recommend the following steps: threshold() the image dilate() the image – this will remove the black line splitting the top and bottom section and also darker artifacts on the lower part findContours() using setting to retrieve only external contours(RETR_EXTERNAL) and simplify the output(CHAIN_APPROX_SIMPLE) process the contours further Step 1:threshold # threshold image ret,thresh = … Read more