cpu implement of bilinear interp

paddle/fluid/operators/bilinear_interp_op.cc

+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+   http://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. */
+
+#include "paddle/fluid/operators/bilinear_interp_op.h"
+
+namespace paddle {
+namespace operators {
+
+using framework::Tensor;
+
+class BilinearInterpOp : public framework::OperatorWithKernel {
+ public:
+  using framework::OperatorWithKernel::OperatorWithKernel;
+
+ protected:
+  void InferShape(framework::InferShapeContext* ctx) const override {
+    PADDLE_ENFORCE(ctx->HasInput("X"),
+                   "Input(X) of BilinearInterOp should not be null.");
+    PADDLE_ENFORCE(ctx->HasOutput("Out"),
+                   "Output(Out) of BilinearInterOp should not be null.");
+
+    auto dim_x = ctx->GetInputDim("Input");  // NCHW format
+    int out_h = ctx->Attrs().Get<int>("out_h");
+    int out_w = ctx->Attrs().Get<int>("out_w");
+    PADDLE_ENFORCE_EQ(dim_x.size(), 4, "X's dimension must be 4");
+
+    std::vector<int64_t> dim_out({dim_x[0], dim_x[1], out_h, out_w});
+    ctx->SetOutputDim("Output", framework::make_ddim(dim_out));
+  }
+};
+
+class BilinearInterpOpMaker : public framework::OpProtoAndCheckerMaker {
+ public:
+  BilinearInterpOpMaker(OpProto* proto, OpAttrChecker* op_checker)
+      : OpProtoAndCheckerMaker(proto, op_checker) {
+    AddInput("X",
+             "The input tensor of bilinear interpolation, 4-D with NCHW shape");
+    AddOutput("Out", "The output tensor with the same shape as X");
+    AddAttr<int>("out_h", "output height of bilinear interpolation op.");
+    AddAttr<int>("out_w", "output weight of bilinear interpolation op.");
+    AddComment(R"DOC(
+          Bilinear interpolation is an extension of linear interpolation for 
+          interpolating functions of two variables (e.g. H-direction and W-direction
+          in this op) on a rectilinear 2D grid. 
+          
+          The key idea is to perform linear interpolation first in one direction, 
+          and then again in the other direction.
+            
+          For details, please refer to Wikipedia: 
+          https://en.wikipedia.org/wiki/Bilinear_interpolation
+         )DOC");
+  }
+};
+
+class BilinearInterpOpGrad : public framework::OperatorWithKernel {
+ public:
+  using framework::OperatorWithKernel::OperatorWithKernel;
+
+ protected:
+  void InferShape(framework::InferShapeContext* ctx) const override {
+    PADDLE_ENFORCE(ctx->HasInput("X"), "Input(X) should not be null");
+    PADDLE_ENFORCE(ctx->HasInput(framework::GradVarName("Out")),
+                   "Input(Out@GRAD) should not be null");
+    auto dim_x = ctx->GetInputDim("X");
+    if (ctx->HasOutput(framework::GradVarName("X"))) {
+      ctx->SetOutputDim(framework::GradVarName("X"), dim_x);
+    }
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle
+
+namespace ops = paddle::operators;
+REGISTER_OP(bilinear_interp, ops::BilinearInterpOp, ops::BilinearInterpOpMaker,
+            bilinear_interp_grad, ops::BilinearInterpOpGrad);
+REGISTER_OP_CPU_KERNEL(bilinear_interp, ops::BilinearInterpKernel<float>);
+REGISTER_OP_CPU_KERNEL(bilinear_interp_grad, ops::BilinearInterpKernel<float>);

paddle/fluid/operators/bilinear_interp_op.h

+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+   http://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. */
+
+#pragma once
+#include "paddle/fluid/framework/eigen.h"
+#include "paddle/fluid/framework/op_registry.h"
+
+namespace paddle {
+namespace operators {
+
+using Tensor = framework::Tensor;
+template <typename T, int MajorType = Eigen::RowMajor,
+          typename IndexType = Eigen::DenseIndex>
+using EigenVector = framework::EigenVector<T, MajorType, IndexType>;
+
+template <typename T>
+class BilinearInterpKernel : public framework::OpKernel<T> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const override {
+    auto* input_t = ctx.Input<Tensor>("X");      // float tensor
+    auto* output_t = ctx.Output<Tensor>("Out");  // float tensor
+    auto* input = input_t->data<T>();
+    auto* output = output_t->mutable_data<T>(ctx.GetPlace());
+
+    int out_h = ctx.Attr<int>("out_h");
+    int out_w = ctx.Attr<int>("out_w");
+    int batch_size = input_t->dims()[0];
+    int channels = input_t->dims()[1];
+    int in_h = input_t->dims()[2];
+    int in_w = input_t->dims()[3];
+
+    int in_hw = in_h * in_w;
+    int out_hw = out_h * out_w;
+    int in_chw = channels * in_hw;
+    int out_chw = channels * out_hw;
+
+    T ratio_h = (out_h > 1) ? static_cast<T>(in_h - 1) / (out_h - 1) : 0.f;
+    T ratio_w = (out_w > 1) ? static_cast<T>(in_w - 1) / (out_w - 1) : 0.f;
+
+    if (in_h == out_h && in_w == out_w) {
+      memcpy(output, input, product(input_t->dims()) * sizeof(T));
+    } else {
+      for (int k = 0; k < batch_size; ++k) {  // loop for batches
+        for (int i = 0; i < out_h; ++i) {     // loop for images
+          int h = ratio_h * i;
+          int hid = (h < in_h - 1) ? 1 : 0;
+          T h1lambda = ratio_h * i - h;
+          T h2lambda = 1 - h1lambda;
+
+          for (int j = 0; j < out_w; ++j) {
+            int w = ratio_w * j;
+            int wid = (w < in_w - 1) ? 1 : 0;
+            T w1lambda = ratio_w * j - w;
+            T w2lambda = 1 - w1lambda;
+            // calculate four position for bilinear interpolation
+            const T* in_pos = &input[k * in_chw + h * in_w + w];
+            T* out_pos = &output[k * out_chw + i * out_w + j];
+
+            for (int c = 0; c < channels; ++c) {  // loop for channels
+              // bilinear interpolation
+              out_pos[0] =
+                  h2lambda * (w2lambda * in_pos[0] + w1lambda * in_pos[wid]) +
+                  h1lambda * (w2lambda * in_pos[hid * in_w] +
+                              w1lambda * in_pos[hid * in_w + wid]);
+              in_pos += in_hw;
+              out_pos += out_hw;
+            }
+          }
+        }
+      }
+    }
+  }
+};
+
+template <typename T>
+class BilinearInterpGradKernel : public framework::OpKernel<T> {
+ public:
+  void Compute(const framework::ExecutionContext& ctx) const override {
+    auto* d_input_t = ctx.Output<Tensor>(framework::GradVarName("X"));
+    auto* d_output_t = ctx.Input<Tensor>(framework::GradVarName("Out"));
+    auto* d_input = d_input_t->mutable_data<T>(ctx.GetPlace());
+    auto* d_output = d_output_t->data<T>();
+
+    int out_h = ctx.Attr<int>("out_h");
+    int out_w = ctx.Attr<int>("out_w");
+    int batch_size = d_input_t->dims()[0];
+    int channels = d_input_t->dims()[1];
+    int in_h = d_input_t->dims()[2];
+    int in_w = d_input_t->dims()[3];
+
+    int in_hw = in_h * in_w;
+    int out_hw = out_h * out_w;
+    int in_chw = channels * in_hw;
+    int out_chw = channels * out_hw;
+
+    T ratio_h = (out_h > 1) ? static_cast<T>(in_h - 1) / (out_h - 1) : 0.f;
+    T ratio_w = (out_w > 1) ? static_cast<T>(in_w - 1) / (out_w - 1) : 0.f;
+
+    if (in_h == out_h && in_w == out_w) {
+      memcpy(d_input, d_output, product(d_input_t->dims()) * sizeof(T));
+    } else {
+      for (int k = 0; k < batch_size; ++k) {  // loop for batches
+        for (int i = 0; i < out_h; ++i) {     // loop for images
+          int h = ratio_h * i;
+          int hid = (h < in_h - 1) ? 1 : 0;
+          T h1lambda = ratio_h * i - h;
+          T h2lambda = 1 - h1lambda;
+
+          for (int j = 0; j < out_w; ++j) {
+            int w = ratio_w * j;
+            int wid = (w < in_w - 1) ? 1 : 0;
+            T w1lambda = ratio_w * j - w;
+            T w2lambda = 1 - w1lambda;
+            T* in_pos = &d_input[k * in_chw + h * in_w + w];
+            const T* out_pos = &d_output[k * out_chw + i * out_w + j];
+
+            for (int c = 0; c < channels; ++c) {  // loop for channels
+              in_pos[0] = h2lambda * w2lambda * out_pos[0];
+              in_pos[wid] = h2lambda * w1lambda * out_pos[0];
+              in_pos[hid * in_w] = h1lambda * w2lambda * out_pos[0];
+              in_pos[hid * in_w + wid] = h1lambda * w1lambda * out_pos[0];
+              in_pos += in_hw;
+              out_pos += out_hw;
+            }
+          }
+        }
+      }
+    }
+  }
+};
+
+}  // namespace operators
+}  // namespace paddle