Raw HDR Rendering

Question

Hi all!

I am currently using Unity for simulation purposes. The images I am producing have specular reflections which are saturated in the output JPG images that are rendered. I was wondering if it is possible in Unity to render images to a raw output format which contains the actual intensity values at that pixel without saturation or clipping. Currently I am rendering like so:

     RenderTexture rt = new RenderTexture(w, h, 24);
     cam.targetTexture = rt;
     cam.Render();

     Texture2D img = new Texture2D(w, h);
     RenderTexture.active = rt;
     img.ReadPixels(new Rect(0, 0, w, h), 0, 0);
     img.Apply();

Many thanks!

Answer 1

You'll need to specify an HDR texture format for both the render texture and output texture if you want to store HDR values;

 //Cache the current active RTs
 RenderTexture prevCam = cam.targetTexture;
 RenderTexture prevActive = RenderTexture.active;
 
 //Use GetTemporary() and ReleaseTemporary() if the RT doesn't need to exist over multiple frames
 //Use ARGBHalf format for both textures (16-bit floating point/channel)
 RenderTexture rt = RenderTexture.GetTemporary (w, h, 24, RenderTextureFormat.ARGBHalf);
 cam.targetTexture = rt;
 cam.Render();
 RenderTexture.active = rt;
 
 //Also set equivalent HDR format here
 Texture2D img = new Texture2D(w, h, TextureFormat.RGBAHalf);
 img.ReadPixels(new Rect(0, 0, w, h), 0, 0);
 img.Apply();
 
 //Cleanup RTs
 cam.targetTexture = prevCam;
 RenderTexture.active = prevActive;
 RenderTexture.ReleaseTemporary (rt);

If you are going to then encode to a format to save on disk, you'll need to use an HDR format (EXR is the main one supported by Unity with a function overload to handle encoding for you).

Raw HDR Rendering

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