cavis/libnd4j/include/ops/declarable/helpers/cpu/image_suppression.cpp

90 lines
4.5 KiB
C++

/*******************************************************************************
* Copyright (c) 2015-2018 Skymind, Inc.
*
* This program and the accompanying materials are made available under the
* terms of the Apache License, Version 2.0 which is available at
* https://www.apache.org/licenses/LICENSE-2.0.
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
* SPDX-License-Identifier: Apache-2.0
******************************************************************************/
//
// @author sgazeos@gmail.com
//
#include <ops/declarable/helpers/image_suppression.h>
//#include <blas/NDArray.h>
namespace nd4j {
namespace ops {
namespace helpers {
template <typename T>
static void nonMaxSuppressionV2_(NDArray* boxes, NDArray* scales, int maxSize, double threshold, NDArray* output) {
std::vector<Nd4jLong> indices(scales->lengthOf());
for (size_t i = 0; i < indices.size(); ++i)
indices[i] = i;
std::sort(indices.begin(), indices.end(), [scales](int i, int j) {return scales->e<T>(i) > scales->e<T>(j);});
std::vector<int> selected;
std::vector<int> selectedIndices(output->lengthOf(), 0);
auto needToSuppressWithThreshold = [threshold] (NDArray& boxes, int previousIndex, int nextIndex) -> bool {
T minYPrev = nd4j::math::nd4j_min(boxes.e<T>(previousIndex, 0), boxes.e<T>(previousIndex, 2));
T minXPrev = nd4j::math::nd4j_min(boxes.e<T>(previousIndex, 1), boxes.e<T>(previousIndex, 3));
T maxYPrev = nd4j::math::nd4j_max(boxes.e<T>(previousIndex, 0), boxes.e<T>(previousIndex, 2));
T maxXPrev = nd4j::math::nd4j_max(boxes.e<T>(previousIndex, 1), boxes.e<T>(previousIndex, 3));
T minYNext = nd4j::math::nd4j_min(boxes.e<T>(nextIndex, 0), boxes.e<T>(nextIndex, 2));
T minXNext = nd4j::math::nd4j_min(boxes.e<T>(nextIndex, 1), boxes.e<T>(nextIndex, 3));
T maxYNext = nd4j::math::nd4j_max(boxes.e<T>(nextIndex, 0), boxes.e<T>(nextIndex, 2));
T maxXNext = nd4j::math::nd4j_max(boxes.e<T>(nextIndex, 1), boxes.e<T>(nextIndex, 3));
T areaPrev = (maxYPrev - minYPrev) * (maxXPrev - minXPrev);
T areaNext = (maxYNext - minYNext) * (maxXNext - minXNext);
if (areaNext <= T(0.f) || areaPrev <= T(0.f)) return false;
T minIntersectionY = nd4j::math::nd4j_max(minYPrev, minYNext);
T minIntersectionX = nd4j::math::nd4j_max(minXPrev, minXNext);
T maxIntersectionY = nd4j::math::nd4j_min(maxYPrev, maxYNext);
T maxIntersectionX = nd4j::math::nd4j_min(maxXPrev, maxXNext);
T intersectionArea =
nd4j::math::nd4j_max(T(maxIntersectionY - minIntersectionY), T(0.0f)) *
nd4j::math::nd4j_max(T(maxIntersectionX - minIntersectionX), T(0.0f));
T intersectionValue = intersectionArea / (areaPrev + areaNext - intersectionArea);
return intersectionValue > threshold;
};
int numSelected = 0;
for (int i = 0; i < boxes->sizeAt(0); ++i) {
if (selected.size() >= output->lengthOf()) break;
bool shouldSelect = true;
// Overlapping boxes are likely to have similar scores,
// therefore we iterate through the selected boxes backwards.
for (int j = numSelected - 1; j >= 0; --j) {
if (needToSuppressWithThreshold(*boxes, indices[i], indices[selectedIndices[j]])) {
shouldSelect = false;
break;
}
}
if (shouldSelect) {
selected.push_back(indices[i]);
selectedIndices[numSelected++] = i;
}
}
for (size_t e = 0; e < selected.size(); ++e)
output->p<int>(e, selected[e]);
}
void nonMaxSuppressionV2(nd4j::LaunchContext * context, NDArray* boxes, NDArray* scales, int maxSize, double threshold, NDArray* output) {
BUILD_SINGLE_SELECTOR(output->dataType(), nonMaxSuppressionV2_, (boxes, scales, maxSize, threshold, output), NUMERIC_TYPES);
}
BUILD_SINGLE_TEMPLATE(template void nonMaxSuppressionV2_, (NDArray* boxes, NDArray* scales, int maxSize, double threshold, NDArray* output), NUMERIC_TYPES);
}
}
}