Changed luma calculation to an approximation method.
Test: Manually flashed
Change-Id: If1c12ca79195f3dbda3a759f9d7df280faf73415
diff --git a/services/surfaceflinger/RegionSamplingThread.cpp b/services/surfaceflinger/RegionSamplingThread.cpp
index 1c1367c..b7e772d 100644
--- a/services/surfaceflinger/RegionSamplingThread.cpp
+++ b/services/surfaceflinger/RegionSamplingThread.cpp
@@ -268,16 +268,6 @@
mDescriptors.erase(who);
}
-namespace {
-// Using Rec. 709 primaries
-inline float getLuma(float r, float g, float b) {
- constexpr auto rec709_red_primary = 0.2126f;
- constexpr auto rec709_green_primary = 0.7152f;
- constexpr auto rec709_blue_primary = 0.0722f;
- return rec709_red_primary * r + rec709_green_primary * g + rec709_blue_primary * b;
-}
-} // anonymous namespace
-
float sampleArea(const uint32_t* data, int32_t width, int32_t height, int32_t stride,
uint32_t orientation, const Rect& sample_area) {
if (!sample_area.isValid() || (sample_area.getWidth() > width) ||
@@ -298,30 +288,23 @@
std::swap(area.left, area.right);
}
- std::array<int32_t, 256> brightnessBuckets = {};
- const int32_t majoritySampleNum = area.getWidth() * area.getHeight() / 2;
+ const uint32_t pixelCount = (area.bottom - area.top) * (area.right - area.left);
+ uint32_t accumulatedLuma = 0;
+ // Calculates luma with approximation of Rec. 709 primaries
for (int32_t row = area.top; row < area.bottom; ++row) {
const uint32_t* rowBase = data + row * stride;
for (int32_t column = area.left; column < area.right; ++column) {
uint32_t pixel = rowBase[column];
- const float r = pixel & 0xFF;
- const float g = (pixel >> 8) & 0xFF;
- const float b = (pixel >> 16) & 0xFF;
- const uint8_t luma = std::round(getLuma(r, g, b));
- ++brightnessBuckets[luma];
- if (brightnessBuckets[luma] > majoritySampleNum) return luma / 255.0f;
+ const uint32_t r = pixel & 0xFF;
+ const uint32_t g = (pixel >> 8) & 0xFF;
+ const uint32_t b = (pixel >> 16) & 0xFF;
+ const uint32_t luma = (r * 7 + b * 2 + g * 23) >> 5;
+ accumulatedLuma += luma;
}
}
- int32_t accumulated = 0;
- size_t bucket = 0;
- for (; bucket < brightnessBuckets.size(); bucket++) {
- accumulated += brightnessBuckets[bucket];
- if (accumulated > majoritySampleNum) break;
- }
-
- return bucket / 255.0f;
+ return accumulatedLuma / (255.0f * pixelCount);
}
std::vector<float> RegionSamplingThread::sampleBuffer(