When I open this image in Photoshop the alpha channel / transparency hides the colour pixels underneath.
http://fc06.deviantart.net/fs70/f/2012/056/e/7/texture_png_by_pamelahflores-d4qyxyy.png
In Photoline I can create a simple layer mask based on alpha (without creating a selection first), and then turn the layer mask off to reveal the "hidden" image. Or I paint with the brush and only affect the alpha.
In Photoshop I cannot seem to access that information. Nor can I paint or erase the transparency only. To me it seems as if Photoshop treats this transparency as something other than an alpha channel. The channel palette only shows the transparency.
Can anyone please explain to me how to convert that transparency to a layer mask, and retain the coloured pixel information? How do I access/reveal the "hidden" image?
Answered my own question: It's identical to Photoline.
With no selection active: Layer-->Layer Mask-->From Transparency.
Done.