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2017-02-22 23:56 GMT+02:00 Ola Zetterqvist <>:

> Has created a license and version information page for my program but
> there were problems with lua5.3.4 doc file "logo.gif".
> Dragging the file to a web browser so it does not seem to have the right view about the file,
> Firefox can do it best, but shows odd things, believe it is a png image.
> Also when to Save_as becomes double suffix logo.gif.png
> Have also been tested in Linux, when you open the file (double-click) so says the
> "File does not appear to be a GIF file"
> (lua-5.3.4.tar.gz is downloaded from LUA site)

You are right.

$ file /usr/local/src/lua-5.3.4/doc/logo.gif
/usr/local/src/lua-5.3.4/doc/logo.gif: PNG image data, 128 x 128,
8-bit/color RGBA, non-interlaced

Linux applications that rely on the ImageMagick library genarally ignore
extensions. You can rename your file to whatever you like, it will just
read it in as binary and use its mighty 'identify' module to find out whether
it is one of the formats it can handle. I suspect that Firefox probably just
handles anything with a graphics extension by the ImageMagick library.
(This is a guess; there might be some other even mare basic library
under it.) E.g. if you rename it to .zip or .pdf, 'display' and friends are not
fooled, but Firefox chokes.

Thanks for this question. Most of the above I did not know before right now.