Improved performance for Kmeans filter.

Bug: 7739334
Change-Id: I5ab1eb429d65f84449a61deca962a47f2b6dbc8b

1 files changed, 41 insertions, 7 deletions

diff --git a/jni/filters/kmeans.cc b/jni/filters/kmeans.cc
index 599657c8e..97cead7bc 100644
--- a/jni/filters/kmeans.cc
+++ b/jni/filters/kmeans.cc
@@ -21,25 +21,59 @@
 extern "C" {
 #endif
 
-void JNIFUNCF(ImageFilterKMeans, nativeApplyFilter, jobject bitmap, jint width, jint height, jint p)
+/*
+ * For reasonable speeds:
+ * k < 30
+ * small_ds_bitmap width/height < 64 pixels.
+ * large_ds_bitmap width/height < 512 pixels
+ *
+ * bad for high-frequency image noise
+ */
+
+void JNIFUNCF(ImageFilterKMeans, nativeApplyFilter, jobject bitmap, jint width, jint height,
+        jobject large_ds_bitmap, jint lwidth, jint lheight, jobject small_ds_bitmap,
+        jint swidth, jint sheight, jint p, jint seed)
 {
     char* destination = 0;
+    char* larger_ds_dst = 0;
+    char* smaller_ds_dst = 0;
     AndroidBitmap_lockPixels(env, bitmap, (void**) &destination);
+    AndroidBitmap_lockPixels(env, large_ds_bitmap, (void**) &larger_ds_dst);
+    AndroidBitmap_lockPixels(env, small_ds_bitmap, (void**) &smaller_ds_dst);
     unsigned char * dst = (unsigned char *) destination;
 
-    int len = width * height * 4;
+    unsigned char * small_ds = (unsigned char *) smaller_ds_dst;
+    unsigned char * large_ds = (unsigned char *) larger_ds_dst;
+
+    // setting for small bitmap
+    int len = swidth * sheight * 4;
     int dimension = 3;
     int stride = 4;
-    int iterations = 4;
+    int iterations = 20;
     int k = p;
+    unsigned int s = seed;
     unsigned char finalCentroids[k * stride];
 
-    // TODO: add downsampling and better heuristic to improve speed, then up iterations
+    // get initial picks from small downsampled image
+    runKMeans<unsigned char, int>(k, finalCentroids, small_ds, len, dimension,
+            stride, iterations, s);
+
+
+    len = lwidth * lheight * 4;
+    iterations = 8;
+    unsigned char nextCentroids[k * stride];
+
+    // run kmeans on large downsampled image
+    runKMeansWithPicks<unsigned char, int>(k, nextCentroids, large_ds, len,
+            dimension, stride, iterations, finalCentroids);
+
+    len = width * height * 4;
 
-    // does K-Means clustering on rgb bitmap colors
-    runKMeans<unsigned char, int>(k, finalCentroids, dst, len, dimension, stride, iterations);
-    applyCentroids<unsigned char, int>(k, finalCentroids, dst, len, dimension, stride);
+    // apply to final image
+    applyCentroids<unsigned char, int>(k, nextCentroids, dst, len, dimension, stride);
 
+    AndroidBitmap_unlockPixels(env, small_ds_bitmap);
+    AndroidBitmap_unlockPixels(env, large_ds_bitmap);
     AndroidBitmap_unlockPixels(env, bitmap);
 }
 #ifdef __cplusplus