Why BMP file format last line of image is first line on file? I'm studying Microsoft Windows Bitmap File Format, extension BMP.
I'm curious to know why scanlines are stored on file from bottom to up: the last scanline on image is the first line on file and the first scanline on image is the last line on file.
The documents that I have read do not explain it.
Here's a quote from Petzold:
  
  
    So, in DIBs, the bottom row of the image is the first row of the file,
    and the top row of the image is the last row in the file. This is
    called a bottom-up organization. Because this organization is
    counterintuitive, you may ask why it's done this way.
    
    Well, it all goes back to the OS/2 Presentation Manager. Someone at
    IBM decided that all coordinate systems in PM—including those for
    windows, graphics, and bitmaps—should be consistent. This provoked a
    debate: Most people, including programmers who have worked with
    full-screen text programming or windowing environments, think in terms
    of vertical coordinates that increase going down the screen. However,
    hardcore computer graphics programmers approach the video display from
    a perspective that originates in the mathematics of analytic geometry.
    This involves a rectangular (or Cartesian) coordinate system where
    increasing vertical coordinates go up in space.
    
    In short, the mathematicians won. Everything in PM was saddled with a
    bottom-left origin, including window coordinates. And that's how DIBs
    came to be this way.
  
  
  Source: Charles Petzold, Programming for Windows 5th Edition, Chapter
  15.


from
https://stackoverflow.com/questions/8346115/why-are-bmps-stored-upside-down