在matlab中从视频中减去背景图像

Question

我正在尝试从视频中读取前 20 帧，将这些图像与我通过取这 20 个图像的中值获得的背景图像一起保存在一个文件夹中。然后我试图从视频中的每一帧中减去这个背景图像并将输出写入一个新视频。但最后，我只在新视频中得到黑色输出并得到以下警告： 警告：没有视频帧写入此文件。该文件可能无效。

在 VideoWriter.VideoWriter>VideoWriter.close 在 307 在 VideoWriter.VideoWriter>VideoWriter.delete 在 256 在 43 帧提取中

我该怎么办？

clear all;
clc;
thresh=100;
workingDir = 'D:/DDP/proj3';
mkdir(workingDir)
mkdir(workingDir,'images')
vid= VideoReader('D:/DDP/sample1.3gp');

for k=1:20
img = readFrame(vid);
filename = [sprintf('%01d',k-1) '.jpg'];
imwrite(img,fullfile(workingDir,'images',filename))    
end
folder = 'D:\DDP\proj3\images\';
filelist = dir( fullfile(folder,'*.jpg') );
filelist = strcat(folder, filesep, {filelist.name});

images = zeros(720,1280,3, numel(filelist), 'double');
for i=1:numel(filelist)
images(:,:,:,i) = double( imread(filelist{i}) );
end
background = uint8(median(images, 4)); 
imwrite(background,'D:\DDP\proj3\images\background.jpg','jpg')

fr_size = size(BW1);
width = fr_size(2);
height = fr_size(1);
fg = zeros(height, width);
vid.CurrentTime = 0;  % Rewind video reader
VW = VideoWriter('D:/DDP/proj3/new');
open(VW);
while hasFrame(vid)
fr = readFrame(vid);
fr_diff = abs(double(fr) - double(background));
for j=1:width
for k=1:height
if ((fr_diff(k,j) > thresh))
fg(k,j) = 255;
else
fg(k,j) = 0;
end
end
end
writeVideo(VW,double(fg)/255);

end
close(VW)
cc=  VideoReader('D:/DDP/proj3/new.avi');
cd= VideoWriter('D:/DDP/proj3/new1');
open(cd);
while hasFrame(cc);
    s=readFrame(cc);
    J = imnoise(s,'salt & pepper',0.02);
    img_filtered = J;
    for c = 1 : 3
    img_filtered(:, :, c) = medfilt2(J(:, :, c), [3, 3]);
    end
writeVideo(cd, double(img_filtered)/255);
end
close(cd);

Answer 1

在您的代码中，错误来自您没有将视频阅读器倒回到第一帧这一事实。您发布的代码似乎与您就背景图像的数据类型为双精度类型所做的评论不符。如果你使用 imread 读取背景图片，它应该是 uint8 类型。这是我的建议：

workingDir = 'D:/DDP';
mkdir(workingDir)
mkdir(workingDir,'images')
vid= VideoReader('D:/DDP/samplee.3gp');

for k=1:20
    img = readFrame(vid);
    filename = [sprintf('%01d',kk-1) '.jpg'];
    imwrite(img,fullfile(workingDir,'images',filename))    
end
folder = 'D:\DDP\images\';
filelist = dir( fullfile(folder,'*.jpg') );
filelist = strcat(folder, filesep, {filelist.name});

images = zeros(720,1280,3, numel(filelist), 'double');
for i=1:numel(filelist)
    images(:,:,:,i) = double( imread(filelist{i}) );
end
background = uint8(median(images, 4)); % Convert background image to uint8 type
imwrite(background,'D:\DDP\images\background.jpg','jpg')

vid.CurrentTime = 0;  % Rewind video reader
VW = VideoWriter('D:/DDP/new');
open(VW);
while hasFrame(vid)
    CDatas(:,:,:) = readFrame(vid) - background;     
    writeVideo(VW,CDatas);   
end
close(VW)