Itseez/opencv — pull request #462 by kobigurk (2013-02-09 23:28:00+00:00)
Title: alpha channel support for 8-bit tiffs

This patch introduces alpha channel support for 8-bit tiffs.
It does that by using the appropriate macro when the image loader module requests for a 4 channel image.
It honors the request of the image loader to load only 3 channels and loads 4 channels only if imread is invoked with flags < 0, same as the patch for PNG some years ago.