function BMPReader(strPathName)

fFile = fopen(strPathName, 'rb');

[data, count] = fread(fFile);

%offset

nOffset = 0;

for i = 1:4

nOffset = nOffset + bitshift(data(10+i), (i-1)*8);

end

%width

nWidth = 0;

for i = 1:4

nWidth = nWidth + bitshift(data(18+i), (i-1)*8);

end

%height

nHeight = 0;

for i = 1:4

nHeight = nHeight + bitshift(data(22+i), (i-1)*8);

end

%bit count

nBitCount = data(29) + bitshift(data(30), 8);

%bmp格式存储是从图片的下到上

img = zeros(nHeight, nWidth);

img = reshape(data(nOffset+1:end), nWidth, nHeight);

img = flipud(img'); %先转置，然后上下交换

imshow(img, [0, 255]);

%close file

fclose(fFile);