I’ve got a texture where the blue channel and the alpha channel have the same information. I have literally copied the alpha-channel data into the blue channel.
Yet, if I do this inside Unity:
fixed4 c = tex2D(_MainTex, IN.uv_MainTex);
o.Albedo = lerp(c.a, c.b, _Lerp);
And then play with lerp, these two will look different (the blue one will be darker).
Why is this?