用matlab进行PPM编码图像处理

以下是PPM编码图像处理的MATLAB代码示例：

1. 读取PPM格式的图像文件

fid = fopen('image.ppm', 'r');
header = fscanf(fid, '%s', [1, 1]);
width = fscanf(fid, '%d', [1, 1]);
height = fscanf(fid, '%d', [1, 1]);
maxval = fscanf(fid, '%d', [1, 1]);
img = fscanf(fid, '%d', [width, height])';
fclose(fid);

2. 将图像转换为二进制流

img_bin = dec2bin(img(:), ceil(log2(maxval)));
img_bin = img_bin(:)';

3. 对二进制流进行PPM编码

ppm_code = '';
count = 1;
while count <= length(img_bin)
    run_length = 0;
    while count+run_length+1 <= length(img_bin) && img_bin(count) == img_bin(count+run_length+1)
        run_length = run_length + 1;
    end
    if run_length > 0
        ppm_code = [ppm_code num2str(run_length+1) img_bin(count)];
        count = count + run_length + 1;
    else
        ppm_code = [ppm_code '1' img_bin(count)];
        count = count + 1;
    end
end

4. 将PPM编码的二进制流转换为字符形式

ppm_code_char = reshape(ppm_code, 8, [])';
ppm_code_char = char(bin2dec(ppm_code_char))';

5. 保存PPM编码的图像文件

fid = fopen('image.ppm.code', 'w');
fprintf(fid, 'P6\n%d %d\n%d\n', width, height, maxval);
fwrite(fid, ppm_code_char, 'uint8');
fclose(fid);

这些代码可以将一个PPM格式的图像文件进行PPM编码，并保存为PPM编码格式的文件。