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# matlab does algorithm processing for specific areas

wangjz38257372 注册会员
2023-02-26 18:13

Part of the answer refers to GPT, GPT_Pro to solve the problem better
If you want to realize only processing areas of interest, you can use the image processing function of Matlab. First, the input video can be read into different frames, and then each frame can be processed. The specific steps are as follows:

1. reads the video file and obtains file information, such as frame number, frame size, etc.
2. reads each frame in a loop, And store it in the matrix
3. convert each frame image into gray image
4. Use the image processing function of Matlab to filter, corrosion, expansion, open operation, close operation, etc.
5. define the region of interest, Define the coordinates of the four corner points of the region of interest
6. Pass the four corner points of the region of interest as parameters to the Matlab function, To perform algorithmic processing on the region of interest
7. To recombine the processed region of interest into the original frame
8. to save the processed result to a new video file

The above is the realization steps of Matlab algorithm processing for specific areas. Example code is as follows:

``````% 读取视频文件，初始化参数
videoFile = 'sampleVideoFile.mp4';
frameCount = 0;
frameWidth = 0;
frameHeight = 0;

if frameCount == 0 % 若是第一帧，则初始化参数
frameCount = frameCount + 1;
frameWidth = size(frame, 2);
frameHeight = size(frame, 1);

% 这里可以定义感兴趣区域的四个角点坐标，即ROI区域
x1 = round(frameWidth * 0.2);  % ROI左上角x坐标
y1 = round(frameHeight * 0.2); % ROI左上角y坐标
x2 = round(frameWidth * 0.8);  % ROI右下角x坐标
y2 = round(frameHeight * 0.8); % ROI右下角y坐标

end

% 将彩色图片转换成灰度图片
grayFrame = rgb2gray(frame);

% 对ROI区域使用Matlab内置函数进行滤波、腐蚀、开闭运算等处理
roiFrame = grayFrame(y1:y2, x1:x2);     % 截取ROI区域图片
filteredRoiFrame = imfilter(roiFrame, fspecial('gaussian', 5)); % 滤波处理
erodedRoiFrame = imerode(filteredRoiFrame, strel('disk', 3));   % 腐蚀处理
openedRoiFrame = imopen(erodedRoiFrame, strel('disk', 3));      % 开运算处理
closedRoiFrame = imclose(openedRoiFrame, strel('disk', 3));     % 闭运算处理

% 将处理好的ROI区域合并到原始图片中
grayFrame(y1:y2, x1:x2) = closedRoiFrame;

% 存储处理后的帧
processedFrames(:, :, :, frameCount) = grayFrame;

frameCount = frameCount + 1;
end

% 创建新的视频文件，将处理后的帧写入文件中
videoWriter = vision.VideoFileWriter('processedVideoFile.mp4', 'FrameRate', 30);
for k = 1 : frameCount-1  % 将处理后的帧写入文件中
step(videoWriter, processedFrames(:, :, :, k));
end
release(videoWriter);     % 释放内存占用
``````

qa3601103 注册会员
2023-02-26 18:13

the reference answer GPT ᴼ ᴾ ᴱ ᴺ ᴬ ᴵ < br / > you can use MATLAB in the Region of Interest(ROI) function to implement algorithmic processing only for specific areas in the video. Here are some steps to do this:

1. Read the video and obtain the video frame rate and frame number
``````video = VideoReader('your_video_file.mp4');
frameRate = video.FrameRate;
numFrames = video.NumFrames;

``````
2. Select the region of interest and create the ROI object
``````x = 100;  % x坐标
y = 100;  % y坐标
width = 200;  % 区域宽度
height = 200;  % 区域高度

roi = images.roi.Rectangle(gca,'Position',[x y width height]);

``````

3. Go through every frame of the video and perform algorithm processing on pixels in ROI

``````outputVideo = VideoWriter('output_file.avi');
outputVideo.FrameRate = frameRate;
open(outputVideo);

for i = 1:numFrames
% 读取帧

% 在帧上应用ROI对象
frame_roi = roi.apply(frame);

% 对ROI中的像素进行算法处理
processed_frame_roi = your_algorithm(frame_roi);

% 将处理后的帧保存到输出视频中
writeVideo(outputVideo, processed_frame_roi);
end

close(outputVideo);

``````

In the above code, we use the ROI object to select the region of interest and apply the ROI to each frame using the Apply method. Then, during processing, we only apply algorithmic processing to pixels in ROI. Finally, we save the processed frames to the output video.

Note: The ROI object needs to be recreated in each frame and applied to the current frame. If you want to select a different area, you can change the properties of the ROI object and then use the new ROI object in the next frame.

sdjnyh2010 注册会员
2023-02-26 18:13

Hello, if you only want to do algorithm processing for a specific area of the video, you can use the video frame to intercept the image, and then use matlab to do area intercept for the image specified area. matlab. The code of a specific area is roughly as follows :

``````A = imread('1.jpg');
imshow(A);
[x,y] = ginput(2);    %确定图像上的两点利用ginput函数，返回值是两点的坐标
pic_1 = imcrop(A,[x(1),y(1),abs(x(1)-x(2)),abs(y(1)-y(2))]);
%利用imcrop函数对图像进行切割，输入参数是一个定点坐标，
%从该定点出发向右abs(x(1)-x(2))，向下abs(y(1)-y(2))的区域进行切割
figure,imshow(pic_1);
imwrite(pic_1,'1.jpg');
``````

Finally do the algorithm processing

daipeiai 注册会员

Publish Time
2023-02-26 18:13
Update Time
2023-02-26 18:13