[Tutor] can not get subtype?

[Danny Yoo]

On Thu, 21 Oct 2004, Ertl, John wrote:

> Thanks.  The header thing might be the place to start.  I am using
> another program to make the png and the person that wrote that code said
> they did not make any changes but knowing them they might have.


[keeping tutor at python.org in CC]


Hi John,


It might also have to do with the way the files are transferred between
machines.  Note that the PNG standard deliberately puts '\r\n' as part of
the header.  This makes it easy to detect damage from improper newline
conversions (a side-effect of treating a PNG file as text instead of
binary.)


The PNG standard explains their rationale here:

http://www.libpng.org/pub/png/spec/1.2/PNG-Rationale.html#R.PNG-file-signature