I'm seeing a noticeable decrease in dynamic range when trying to capture a still image of a rendered OpenGL scene that employs alpha blending. I've attached an example patch and two images, one a direct screen grab of the render window, the other a PNG generated with the "exportimage" message to jit.matrix. To my eyes the screen grab clearly has a greater dynamic range.
Would anyone care to take a look and point me in the right direction here? The end goal is to be able to capture pixel accurate still captures of my rendered scene.
Mac OSX 10.7.5
Macbook Pro, 2.3Ghz i7
AMD Radeon HD 6750M