Realtime Compositor: Implement Tone Map node

This patch implements the tone map node for the realtime compositor
based on the two papers:

Reinhard, Erik, et al. "Photographic tone reproduction for digital
images." Proceedings of the 29th annual conference on Computer graphics
and interactive techniques. 2002.

Reinhard, Erik, and Kate Devlin. "Dynamic range reduction inspired by
photoreceptor physiology." IEEE transactions on visualization and
computer graphics 11.1 (2005): 13-24.

The original implementation should be revisited later due to apparent
incompatibilities with the reference papers, which makes the operation
less useful.

Differential Revision: https://developer.blender.org/D16306

Reviewed By: Clement Foucault

2 files changed, 89 insertions, 0 deletions

diff --git a/source/blender/compositor/realtime_compositor/algorithms/COM_algorithm_parallel_reduction.hh b/source/blender/compositor/realtime_compositor/algorithms/COM_algorithm_parallel_reduction.hh
index 9d0851eff84..b094782c18e 100644
--- a/source/blender/compositor/realtime_compositor/algorithms/COM_algorithm_parallel_reduction.hh
+++ b/source/blender/compositor/realtime_compositor/algorithms/COM_algorithm_parallel_reduction.hh
@@ -27,6 +27,13 @@ float sum_blue(Context &context, GPUTexture *texture);
  * coefficients to compute the luminance. */
 float sum_luminance(Context &context, GPUTexture *texture, float3 luminance_coefficients);
 
+/* Computes the sum of the logarithm of the luminance of all pixels in the given texture, using the
+ * given luminance coefficients to compute the luminance. */
+float sum_log_luminance(Context &context, GPUTexture *texture, float3 luminance_coefficients);
+
+/* Computes the sum of the colors of all pixels in the given texture. */
+float4 sum_color(Context &context, GPUTexture *texture);
+
 /* --------------------------------------------------------------------
  * Sum Of Squared Difference Reductions.
  */
@@ -55,4 +62,20 @@ float sum_luminance_squared_difference(Context &context,
                                        float3 luminance_coefficients,
                                        float subtrahend);
 
+/* --------------------------------------------------------------------
+ * Maximum Reductions.
+ */
+
+/* Computes the maximum luminance of all pixels in the given texture, using the given luminance
+ * coefficients to compute the luminance. */
+float maximum_luminance(Context &context, GPUTexture *texture, float3 luminance_coefficients);
+
+/* --------------------------------------------------------------------
+ * Minimum Reductions.
+ */
+
+/* Computes the minimum luminance of all pixels in the given texture, using the given luminance
+ * coefficients to compute the luminance. */
+float minimum_luminance(Context &context, GPUTexture *texture, float3 luminance_coefficients);
+
 }  // namespace blender::realtime_compositor
diff --git a/source/blender/compositor/realtime_compositor/algorithms/intern/algorithm_parallel_reduction.cc b/source/blender/compositor/realtime_compositor/algorithms/intern/algorithm_parallel_reduction.cc
index 3266ccd14eb..139c58bc190 100644
--- a/source/blender/compositor/realtime_compositor/algorithms/intern/algorithm_parallel_reduction.cc
+++ b/source/blender/compositor/realtime_compositor/algorithms/intern/algorithm_parallel_reduction.cc
@@ -134,6 +134,34 @@ float sum_luminance(Context &context, GPUTexture *texture, float3 luminance_coef
   return sum;
 }
 
+float sum_log_luminance(Context &context, GPUTexture *texture, float3 luminance_coefficients)
+{
+  GPUShader *shader = context.shader_manager().get("compositor_sum_log_luminance");
+  GPU_shader_bind(shader);
+
+  GPU_shader_uniform_3fv(shader, "luminance_coefficients", luminance_coefficients);
+
+  float *reduced_value = parallel_reduction_dispatch(context, texture, shader, GPU_R32F);
+  const float sum = *reduced_value;
+  MEM_freeN(reduced_value);
+  GPU_shader_unbind();
+
+  return sum;
+}
+
+float4 sum_color(Context &context, GPUTexture *texture)
+{
+  GPUShader *shader = context.shader_manager().get("compositor_sum_color");
+  GPU_shader_bind(shader);
+
+  float *reduced_value = parallel_reduction_dispatch(context, texture, shader, GPU_RGBA32F);
+  const float4 sum = float4(reduced_value);
+  MEM_freeN(reduced_value);
+  GPU_shader_unbind();
+
+  return sum;
+}
+
 /* --------------------------------------------------------------------
  * Sum Of Squared Difference Reductions.
  */
@@ -202,4 +230,42 @@ float sum_luminance_squared_difference(Context &context,
   return sum;
 }
 
+/* --------------------------------------------------------------------
+ * Maximum Reductions.
+ */
+
+float maximum_luminance(Context &context, GPUTexture *texture, float3 luminance_coefficients)
+{
+  GPUShader *shader = context.shader_manager().get("compositor_maximum_luminance");
+  GPU_shader_bind(shader);
+
+  GPU_shader_uniform_3fv(shader, "luminance_coefficients", luminance_coefficients);
+
+  float *reduced_value = parallel_reduction_dispatch(context, texture, shader, GPU_R32F);
+  const float maximum = *reduced_value;
+  MEM_freeN(reduced_value);
+  GPU_shader_unbind();
+
+  return maximum;
+}
+
+/* --------------------------------------------------------------------
+ * Minimum Reductions.
+ */
+
+float minimum_luminance(Context &context, GPUTexture *texture, float3 luminance_coefficients)
+{
+  GPUShader *shader = context.shader_manager().get("compositor_minimum_luminance");
+  GPU_shader_bind(shader);
+
+  GPU_shader_uniform_3fv(shader, "luminance_coefficients", luminance_coefficients);
+
+  float *reduced_value = parallel_reduction_dispatch(context, texture, shader, GPU_R32F);
+  const float minimum = *reduced_value;
+  MEM_freeN(reduced_value);
+  GPU_shader_unbind();
+
+  return minimum;
+}
+
 }  // namespace blender::realtime_compositor