[arrayfire] 74/408: Added C API for Harris corner detector

[Ghislain Vaillant]

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ghisvail-guest pushed a commit to branch debian/sid
in repository arrayfire.

commit 7c41de954b473ec91b540e126e45b00c2852ed9f
Author: Peter Andreas Entschev <peter at arrayfire.com>
Date:   Thu Jul 2 13:37:35 2015 -0400

    Added C API for Harris corner detector
---
 src/api/c/harris.cpp | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)

diff --git a/src/api/c/harris.cpp b/src/api/c/harris.cpp
new file mode 100644
index 0000000..5781e19
--- /dev/null
+++ b/src/api/c/harris.cpp
@@ -0,0 +1,84 @@
+/*******************************************************
+ * Copyright (c) 2015, ArrayFire
+ * All rights reserved.
+ *
+ * This file is distributed under 3-clause BSD license.
+ * The complete license agreement can be obtained at:
+ * http://arrayfire.com/licenses/BSD-3-Clause
+ ********************************************************/
+
+#include <af/dim4.hpp>
+#include <af/defines.h>
+#include <af/features.h>
+#include <af/vision.h>
+#include <handle.hpp>
+#include <err_common.hpp>
+#include <backend.hpp>
+#include <features.hpp>
+#include <harris.hpp>
+
+using af::dim4;
+using namespace detail;
+
+template<typename T, typename convAccT>
+static af_features harris(af_array const &in, const unsigned max_corners,
+                          const float min_response, const float sigma,
+                          const unsigned filter_len, const float k_thr)
+{
+    Array<float> x = createEmptyArray<float>(dim4());
+    Array<float> y = createEmptyArray<float>(dim4());
+    Array<float> score = createEmptyArray<float>(dim4());
+
+    af_features_t feat;
+    feat.n = harris<T, convAccT>(x, y, score,
+                                 getArray<T>(in), max_corners, min_response,
+                                 sigma, filter_len, k_thr);
+
+    Array<float> orientation = createValueArray<float>(feat.n, 0.0);
+    Array<float> size = createValueArray<float>(feat.n, 1.0);
+
+    feat.x           = getHandle(x);
+    feat.y           = getHandle(y);
+    feat.score       = getHandle(score);
+    feat.orientation = getHandle(orientation);
+    feat.size        = getHandle(size);
+
+    return getFeaturesHandle(feat);
+}
+
+
+af_err af_harris(af_features *out, const af_array in, const unsigned max_corners,
+                 const float min_response, const float sigma,
+                 const unsigned block_size, const float k_thr)
+{
+    try {
+        ArrayInfo info = getInfo(in);
+        af::dim4 dims  = info.dims();
+        dim_t in_ndims = dims.ndims();
+
+        unsigned filter_len = (block_size == 0) ? floor(6.f * sigma) : block_size;
+        if (block_size == 0 && filter_len % 2 == 0)
+            filter_len--;
+
+        const unsigned edge = (block_size > 0) ? block_size / 2 : filter_len / 2;
+
+        DIM_ASSERT(1, (in_ndims == 2));
+        ARG_ASSERT(1, (dims[0] >= (dim_t)(2*edge+1) || dims[1] >= (dim_t)(2*edge+1)));
+        ARG_ASSERT(3, (max_corners > 0) || (min_response > 0.0f));
+        ARG_ASSERT(7, (k_thr >= 0.01f));
+        // Upper limits for sigma and block_size are due to convolve2 template
+        // at maximum length of 31 elements for the filter in OpenCL
+        ARG_ASSERT(4, (block_size > 2) || (sigma >= 0.5f && sigma <= 5.f));
+        ARG_ASSERT(5, (block_size <= 32));
+
+        af_dtype type  = info.getType();
+        switch(type) {
+            case f64: *out = harris<double, double>(in, max_corners, min_response, sigma, filter_len, k_thr); break;
+            case f32: *out = harris<float , float >(in, max_corners, min_response, sigma, filter_len, k_thr); break;
+            default : TYPE_ERROR(1, type);
+        }
+    }
+    CATCHALL;
+
+    return AF_SUCCESS;
+}

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