Render to texture with HDR enabled?

I am trying to use render to texture with a hdr camera. The result I get looks like the post process effects do not have HDR enabled.

Here is what I do:

 var tex = new Texture2D(width, height, TextureFormat.ARGB32, false);
 var target = new RenderTexture(width, height, 32, RenderTextureFormat.ARGB32);
 camera.targetTexture= target;
 camera.Render();
 RenderTexture.active = target;
 tex .ReadPixels(new Rect(0, 0, renderTexture.width, renderTexture.height), 0, 0);
 tex .Apply(false);

Unity 5.6.0f3

Post Processing Stack 1.0.2