ColorShift.OnRenderImage C# (CSharp) Method

    void OnRenderImage(RenderTexture source, RenderTexture destination)
    {
        if (accumTexture == null || accumTexture.width != source.width || accumTexture.height != source.height){
            DestroyImmediate(accumTexture);
            accumTexture = new RenderTexture(source.width, source.height, 0,RenderTextureFormat.ARGB32);
            accumTexture.hideFlags = HideFlags.HideAndDontSave;
            Graphics.Blit( source, accumTexture );
        }
        accumTexture.MarkRestoreExpected();

        material.SetTexture("iChannel0", accumTexture);
        material.SetFloat ("_Strength", strength);

        Graphics.Blit (source, destination, material);
        Graphics.Blit(destination,accumTexture);
    }