bitmap size and file size

When I run the code shown in the link http://in.mathworks.com/matlabcentral/fileexchange/13584-compression-ratio, i got the output

Among these what is the difference between ' FileSize ' and ' BitmapSize ' .How this FileSize is calculated here. The formula for compression ratio is also here.

Answer 1

[Walter Roberson]

"How this FileSize is calculated here."

Record the output of dir() of the file. Access the "bytes" field of the result.

"' BitmapSize '"

Bitmapsize is Height time Width.

"The formula for compression ratio is also here."

See https://www.mathworks.com/matlabcentral/answers/27322-cr-bit-per-pixel-image-compression#comment_410392

[Renjith V Ravi]

Is there any unit for the ' FileSize ' in above example

[Walter Roberson]

Bytes.

[Walter Roberson]

Note that for compression calculations you need to know the number of channels per pixel and the number of bits per channel per pixel.