My goal is to take an ico-image, like this [wikipedia.ico][1] and flip it vertically. My first attempt was

    $ convert -flip wikipedia.ico flipped.ico

And it works, except that the resulting file `flipped.ico` is larger than the original:

    $ identify wikipedia.ico 
    wikipedia.ico[0] ICO 48x48 48x48+0+0 4-bit sRGB 2734B 0.000u 0:00.000
    wikipedia.ico[1] ICO 32x32 32x32+0+0 4-bit sRGB 2734B 0.000u 0:00.000
    wikipedia.ico[2] ICO 16x16 16x16+0+0 4-bit sRGB 2734B 0.000u 0:00.000

    $ identify flipped.ico 
    flipped.ico[0] ICO 48x48 48x48+0+0 8-bit sRGB 15086B 0.000u 0:00.000
    flipped.ico[1] ICO 32x32 32x32+0+0 8-bit sRGB 15086B 0.000u 0:00.000
    flipped.ico[2] ICO 16x16 16x16+0+0 8-bit sRGB 15086B 0.000u 0:00.000

Adding the flag `-depth 4` does not help. 

How can I do I get the exact same image, simply flipped?

*Edit*:

Thanks to Paolo Gibellini's answer, it got a smaller file `flipped.ico`. However, using  `-colors 16 -depth 4` still results in a file, that is much larger than the original:

    $ convert -flip -colors 16 -depth 4 wikipedia.ico flipped.ico
    $ ls -l flipped.ico wikipedia.ico
    [...] 10734 May 14 21:05 flipped.ico
    [...]  2734 May 14 09:41 wikipedia.ico
    $ identify flipped.ico 
    flipped.ico[0] ICO 48x48 48x48+0+0 8-bit sRGB 10734B 0.000u 0:00.009
    flipped.ico[1] ICO 32x32 32x32+0+0 4-bit sRGB 10734B 0.000u 0:00.000
    flipped.ico[2] ICO 16x16 16x16+0+0 4-bit sRGB 10734B 0.000u 0:00.000
I am running this on a debian pc. In the first line, there still seems to be some 8-bit image. Is there a way to have flipped.ico exactly the same size? Dos this really work on windows, as mentioned in the answer?
 
  [1]: https://en.wikipedia.org/static/favicon/wikipedia.ico