From 3d732f1a5e921a13fece9551e73e325d6c66ab58 Mon Sep 17 00:00:00 2001
From: Amir MOHAMMADI <amir.mohammadi@idiap.ch>
Date: Fri, 7 Feb 2020 15:29:11 +0100
Subject: [PATCH] Add a Gaussian blur filter
---
bob/learn/tensorflow/image/__init__.py | 19 +++++++++++++
bob/learn/tensorflow/image/filter.py | 38 ++++++++++++++++++++++++++
2 files changed, 57 insertions(+)
create mode 100644 bob/learn/tensorflow/image/__init__.py
create mode 100644 bob/learn/tensorflow/image/filter.py
diff --git a/bob/learn/tensorflow/image/__init__.py b/bob/learn/tensorflow/image/__init__.py
new file mode 100644
index 00000000..9a896284
--- /dev/null
+++ b/bob/learn/tensorflow/image/__init__.py
@@ -0,0 +1,19 @@
+from .filter import gaussian_kernel, GaussianFilter
+
+# gets sphinx autodoc done right - don't remove it
+def __appropriate__(*args):
+ """Says object was actually declared here, an not on the import module.
+
+ Parameters:
+
+ *args: An iterable of objects to modify
+
+ Resolves `Sphinx referencing issues
+ <https://github.com/sphinx-doc/sphinx/issues/3048>`
+ """
+ for obj in args:
+ obj.__module__ = __name__
+
+
+__appropriate__(GaussianFilter)
+__all__ = [_ for _ in dir() if not _.startswith("_")]
diff --git a/bob/learn/tensorflow/image/filter.py b/bob/learn/tensorflow/image/filter.py
new file mode 100644
index 00000000..3ac149db
--- /dev/null
+++ b/bob/learn/tensorflow/image/filter.py
@@ -0,0 +1,38 @@
+import tensorflow as tf
+
+
+def gaussian_kernel(size: int, mean: float, std: float):
+ """Makes 2D gaussian Kernel for convolution.
+ Code adapted from: https://stackoverflow.com/a/52012658/1286165"""
+
+ d = tf.distributions.Normal(mean, std)
+
+ vals = d.prob(tf.range(start=-size, limit=size + 1, dtype=tf.float32))
+
+ gauss_kernel = tf.einsum("i,j->ij", vals, vals)
+
+ return gauss_kernel / tf.reduce_sum(gauss_kernel)
+
+
+class GaussianFilter:
+ """A class for blurring images"""
+
+ def __init__(self, size=13, mean=0.0, std=3.0, **kwargs):
+ super().__init__(**kwargs)
+ self.size = size
+ self.mean = mean
+ self.std = std
+ self.gauss_kernel = gaussian_kernel(size, mean, std)[:, :, None, None]
+
+ def __call__(self, image):
+ shape = tf.shape(image)
+ image = tf.reshape(image, [-1, shape[-3], shape[-2], shape[-1]])
+ input_channels = shape[-1]
+ gauss_kernel = tf.tile(self.gauss_kernel, [1, 1, input_channels, 1])
+ return tf.nn.depthwise_conv2d(
+ image,
+ gauss_kernel,
+ strides=[1, 1, 1, 1],
+ padding="SAME",
+ data_format="NHWC",
+ )
--
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