6 files changed, 90 insertions, 0 deletions
diff --git a/filters/__init__.py b/filters/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/filters/__init__.py
diff --git a/filters/convolution.py b/filters/convolution.py
new file mode 100644
index 0000000..0a4cf9e
--- /dev/null
+++ b/filters/convolution.py
@@ -0,0 +1,16 @@
+# Copyright 2016 (c) Egor Tensin <Egor.Tensin@gmail.com>
+# This file is part of the "Simple image filters" project.
+# For details, see https://github.com/egor-tensin/filters.
+# Distributed under the MIT License.
+
+import numpy as np
+
+def convolve(img, kernel):
+    #print(kernel)
+    radius = kernel.shape[0] // 2
+    output = np.zeros(img.shape, dtype=img.dtype)
+    for i in range(radius, img.shape[0] - radius):
+        for j in range(radius, img.shape[1] - radius):
+            neighborhood = img[i - radius:i + radius + 1, j - radius:j + radius + 1]
+            output[i, j] = np.sum(neighborhood * kernel)
+    return output
diff --git a/filters/kernel/__init__.py b/filters/kernel/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/filters/kernel/__init__.py
diff --git a/filters/kernel/box_blur.py b/filters/kernel/box_blur.py
new file mode 100644
index 0000000..b9c5d60
--- /dev/null
+++ b/filters/kernel/box_blur.py
@@ -0,0 +1,10 @@
+# Copyright 2016 (c) Egor Tensin <Egor.Tensin@gmail.com>
+# This file is part of the "Simple image filters" project.
+# For details, see https://github.com/egor-tensin/filters.
+# Distributed under the MIT License.
+
+import numpy as np
+
+def gen_kernel(radius):
+    size = radius * 2 + 1
+    return np.ones((size, size)) / size ** 2
diff --git a/filters/kernel/gaussian_blur.py b/filters/kernel/gaussian_blur.py
new file mode 100644
index 0000000..5557b79
--- /dev/null
+++ b/filters/kernel/gaussian_blur.py
@@ -0,0 +1,15 @@
+# Copyright 2016 (c) Egor Tensin <Egor.Tensin@gmail.com>
+# This file is part of the "Simple image filters" project.
+# For details, see https://github.com/egor-tensin/filters.
+# Distributed under the MIT License.
+
+import numpy as np
+
+def gen_kernel(radius, sigma):
+    kernel = np.array([[i ** 2 + j ** 2
+        for i in range(-radius, radius + 1)]
+        for j in range(-radius, radius + 1)])
+    kernel = -kernel / (2 * sigma ** 2)
+    kernel = np.exp(kernel)
+    kernel = kernel / np.sum(kernel)
+    return kernel
diff --git a/filters/kernel/shift.py b/filters/kernel/shift.py
new file mode 100644
index 0000000..4e1e497
--- /dev/null
+++ b/filters/kernel/shift.py
@@ -0,0 +1,49 @@
+# Copyright 2016 (c) Egor Tensin <Egor.Tensin@gmail.com>
+# This file is part of the "Simple image filters" project.
+# For details, see https://github.com/egor-tensin/filters.
+# Distributed under the MIT License.
+
+from enum import Enum
+
+import numpy as np
+
+class Direction(Enum):
+    NORTH = 'N'
+    NORTH_EAST = 'NE'
+    NORTH_WEST = 'NW'
+    SOUTH = 'S'
+    SOUTH_EAST = 'SE'
+    SOUTH_WEST = 'SW'
+    EAST = 'E'
+    WEST = 'W'
+
+    def gen_kernel(self, distance):
+        radius = distance
+        size = 2 * radius + 1
+        kernel = np.zeros((size, size))
+        x, y = radius, radius
+
+        if self is Direction.NORTH:
+            x = -1
+        elif self is Direction.NORTH_EAST:
+            x, y = -1, 0
+        elif self is Direction.EAST:
+            y = 0
+        elif self is Direction.SOUTH_EAST:
+            x, y = 0, 0
+        elif self is Direction.SOUTH:
+            x = 0
+        elif self is Direction.SOUTH_WEST:
+            x, y = 0, -1
+        elif self is Direction.WEST:
+            y = -1
+        elif self is Direction.NORTH_WEST:
+            x, y = -1, -1
+        else:
+            raise NotImplementedError('unsupported direction: ' + str(self))
+
+        kernel[x, y] = 1
+        return kernel
+
+    def __str__(self):
+        return self.value