Re: GM loses transparency on some grayscale PNG images?

Now that I look at the related code in Magick++/lib/Options.cpp I see 
that it does this:

Magick::ImageType Magick::Options::type ( void ) const
{
   return _imageInfo->type;
}

The ImageInfo structure is used for input options rather than for 
output.

The related code in Magick++/lib/Image.cpp forwards the request like:

// Image representation type
Magick::ImageType Magick::Image::type ( void ) const
{

   ExceptionInfo exceptionInfo;
   GetExceptionInfo( &exceptionInfo );
   ImageType image_type = constOptions()->type();
   if ( image_type == UndefinedType )
     image_type= GetImageType(constImage(), &exceptionInfo);
   throwImageException( exceptionInfo );
   return image_type;
}

The core library function which returns the desired 
value is GetImageType() in magick/analyze.c.  We can see that this 
function is called if the value returned by constOptions()->type() is 
UndefinedType.  I assume that it is not returning UndefinedType.

The default value for ImageInfo->type is UndefinedType (0).  What I am 
wondering is why the value is apparently not UndefinedType in your 
program?

Bob
-- 
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
Public Key,     http://www.simplesystems.org/users/bfriesen/public-key.txt