What is image contour?

The corrosion in Opencv refers to the concept of corrosion in nature and the principle of opencv corrosion. The corroded convolution kernel is a matrix of all 1.

Canny is called the ultimate method of edge detection, because it is very simple compared with Sobel, Schell and Laplace filtering. On the one hand, Canny handles edges very carefully and has good results. In addition, Canny is also very simple, and only

There must be many edge lines in an image. The main function of high pass filtering is to detect edges. Opencv provides us with several high pass filters.

The advantage of bilateral filtering is that it can preserve the edge and smooth the edge area at the same time. The main function of bilateral filtering is beauty.

The function of filtering is to get another image through a filter, where the filter is also called convolution kernel, and the filtering process is called convolution.

In opencv, image transformation is a tool we often use, including image scaling, image flip, image rotation, etc. How to operate it?

Method of making watermark and adding watermark to image in opencv

The api of image fusion is addWeighted (A, alpha, B, bate, gamma). If two images are to be fused, their dimensions must be the same.

In Opencv, two images can operate on each other, including addition, subtraction, multiplication and division. What is the effect of the two images after operation?

Opencv mouse control case, opencv realizes the basic drawing of mouse

Opencv's api for drawing text is:

The Opencv polygon drawing api is:

Opencv's api for drawing ellipses is ellipses. Let's take a look at the attributes of ellipses.

The line api used by opencv to draw straight lines has four important attributes:

For an image, we can do some processing on its channels. The normal image includes three channels of BGR. How can we separate and merge the channels together? The first two apis you need to know to realize channel separation and merging.

What is Mat?

The color space of Opencv can be converted to each other. It is very common for Opencv to convert the color space.

Trackbar controls are often used in experiments. What exactly is a trackbar like? The following figure shows the style of trackbar.

To control the mouse, Opencv must first set a callback function for the window. The prototype is: setMouseCallback (winname, callback, userdata)

It is very simple to use opencv to record video data into files. opencv provides us with a class that specifically saves video frames into video files. We can call it directly.

Opencv reads video frames from multimedia files in the same way as it reads keyframes from devices, using the VideoCapture API. The difference is that the input parameters are different.

Opencv helps us to provide a very useful video capture api. We only need to call a few simple apis to collect video data. Let's see what apis are available.

The api used by Opencv to save pictures is imwrite (name, img)

Opencv loads an image and displays it in the window.