COMPMID-588: Port Equalize Histogram to new validation

Change-Id: Iff50adf2993bd69c2696a47559d6b2e0011fed87
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/110177
Tested-by: Jenkins <bsgcomp@arm.com>
Reviewed-by: Anthony Barbier <anthony.barbier@arm.com>

1 files changed, 90 insertions, 0 deletions

diff --git a/tests/validation/reference/EqualizeHistogram.cpp b/tests/validation/reference/EqualizeHistogram.cpp
new file mode 100644
index 0000000000..0e966cd0b4
--- /dev/null
+++ b/tests/validation/reference/EqualizeHistogram.cpp
@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2017-2018 ARM Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#include "EqualizeHistogram.h"
+
+namespace arm_compute
+{
+namespace test
+{
+namespace validation
+{
+namespace reference
+{
+template <typename T>
+SimpleTensor<T> equalize_histogram(const SimpleTensor<T> &src)
+{
+    const size_t num_bins = 256; // 0-255 inclusive
+
+    std::vector<T>        lut(num_bins);
+    std::vector<uint32_t> hist(num_bins);
+    std::vector<uint32_t> cd(num_bins); // cumulative distribution
+
+    SimpleTensor<T> dst(src.shape(), src.data_type());
+
+    // Create the histogram
+    for(int element_idx = 0; element_idx < src.num_elements(); ++element_idx)
+    {
+        hist[src[element_idx]]++;
+    }
+
+    // Calculate cumulative distribution
+    std::partial_sum(hist.begin(), hist.end(), cd.begin());
+
+    // Get the number of pixels that have the lowest non-zero value
+    const uint32_t cd_min = *std::find_if(hist.begin(), hist.end(), [](const uint32_t &x)
+    {
+        return x > 0;
+    });
+
+    const size_t total_num_pixels = cd.back();
+
+    // Single color - create linear distribution
+    if(total_num_pixels == cd_min)
+    {
+        std::iota(lut.begin(), lut.end(), 0);
+    }
+    else
+    {
+        const float diff = total_num_pixels - 1;
+
+        for(size_t i = 0; i < num_bins; ++i)
+        {
+            lut[i] = lround((cd[i] - cd_min) / diff * 255.f);
+        }
+    }
+
+    // Fill output tensor with equalized values
+    for(int i = 0; i < src.num_elements(); ++i)
+    {
+        dst[i] = lut[src[i]];
+    }
+
+    return dst;
+}
+
+template SimpleTensor<uint8_t> equalize_histogram(const SimpleTensor<uint8_t> &src);
+} // namespace reference
+} // namespace validation
+} // namespace test
+} // namespace arm_compute