check if texture alpha channel exists

Hi,

after loading a texture how can i check if the source image (PNG) has an alpha channel/transparent pixels or not?

I need to know this to set the flags material.diffuseTexture.hasAlpha and material.useAlphaFromDiffuseTexture to true.

In my scenario the images/textures which will be used later in the application are not predefined.

The only way is that i automatically detect if i need to enable the alpha flags.