Load OpenExr image's alpha value in mobile devices.

I have a float 16f openExr picture exported from a render texture, the alpha channel storing some data. In standalone mode, I can get access to the picture's alpha value (the image is in dx5 format) no matter in shaders or in the image preview window.


The problem is when I switch to mobile platforms, I can no longer view the openExr picture's alpha channel whatever its format. I can either read it's original storing alpha value in the shader (the read value actually looks like the intensity of the pixel. The M in RGBM encoding). The problem is how can I load the original OpenExr picture's alpha value on mobile devices.