Vignette filter: precompute more values, simplify math, cleanup code
Change-Id: I29cfc313a5173fd393944dd9af58d0111a3d726a
diff --git a/tests/RenderScriptTests/ImageProcessing/src/com/android/rs/image/vignette.rsh b/tests/RenderScriptTests/ImageProcessing/src/com/android/rs/image/vignette.rsh
index 9429564..a1e4ae5 100644
--- a/tests/RenderScriptTests/ImageProcessing/src/com/android/rs/image/vignette.rsh
+++ b/tests/RenderScriptTests/ImageProcessing/src/com/android/rs/image/vignette.rsh
@@ -14,48 +14,43 @@
* limitations under the License.
*/
-static float2 scale;
-static float2 center, dimensions;
-static float range, inv_max_dist, shade, slope;
-static float2 overDimensions;
+static float2 neg_center, axis_scale, inv_dimensions;
+static float sloped_neg_range, sloped_inv_max_dist, shade, opp_shade;
void init_vignette(uint32_t dim_x, uint32_t dim_y, float center_x, float center_y,
float desired_scale, float desired_shade, float desired_slope) {
- center.x = center_x;
- center.y = center_y;
- dimensions.x = (float)dim_x;
- dimensions.y = (float)dim_y;
+ neg_center.x = -center_x;
+ neg_center.y = -center_y;
+ inv_dimensions.x = 1.f / (float)dim_x;
+ inv_dimensions.y = 1.f / (float)dim_y;
- float max_dist = 0.5;
- if (dim_x > dim_y) {
- scale.x = 1.0;
- scale.y = dimensions.y / dimensions.x;
- max_dist *= sqrt(scale.y*scale.y + 1);
- } else {
- scale.x = dimensions.x / dimensions.y;
- scale.y = 1.0;
- max_dist *= sqrt(scale.x*scale.x + 1);
- }
- inv_max_dist = 1.0/max_dist;
+ axis_scale = (float2)1.f;
+ if (dim_x > dim_y)
+ axis_scale.y = (float)dim_y / (float)dim_x;
+ else
+ axis_scale.x = (float)dim_x / (float)dim_y;
+
+ const float max_dist = 0.5 * length(axis_scale);
+ sloped_inv_max_dist = desired_slope * 1.f/max_dist;
+
// Range needs to be between 1.3 to 0.6. When scale is zero then range is
// 1.3 which means no vignette at all because the luminousity difference is
// less than 1/256. Expect input scale to be between 0.0 and 1.0.
- range = 1.3 - 0.7*sqrt(desired_scale);
- shade = desired_shade;
- slope = desired_slope;
+ const float neg_range = 0.7*sqrt(desired_scale) - 1.3;
+ sloped_neg_range = exp(neg_range * desired_slope);
- overDimensions = ((float2)1.f) / dimensions;
+ shade = desired_shade;
+ opp_shade = 1.f - desired_shade;
}
void root(const uchar4 *in, uchar4 *out, uint32_t x, uint32_t y) {
// Convert x and y to floating point coordinates with center as origin
const float4 fin = convert_float4(*in);
- float2 coord = {(float)x, (float)y};
- coord *= overDimensions;
- coord -= center;
- const float dist = length(scale * coord);
- const float lumen = shade / (1.0 + exp((dist * inv_max_dist - range) * slope)) + (1.0 - shade);
+ const float2 inCoord = {(float)x, (float)y};
+ const float2 coord = mad(inCoord, inv_dimensions, neg_center);
+ const float sloped_dist_ratio = length(axis_scale * coord) * sloped_inv_max_dist;
+ const float lumen = opp_shade + shade / ( 1.0 + sloped_neg_range * exp(sloped_dist_ratio) );
float4 fout;
fout.rgb = fin.rgb * lumen;
fout.w = fin.w;