added links to skimage

Author: jo-mueller

05_feature_extraction/02_thresholding_and_noise.ipynb

@@ -66,7 +66,7 @@
    "id": "20b37f1d-7520-4d49-9d57-31267920af03",
    "metadata": {},
    "source": [
-    "There are different types of pixel noise. *Gaussian noise*, for instance, adds a small value to every pixel according to a gaussian distribution. The gaussian filter provides a good way to deal with this."
+    "There are different types of pixel noise. *Gaussian noise*, for instance, adds a small value to every pixel according to a gaussian distribution. The [gaussian filter](https://scikit-image.org/docs/stable/api/skimage.filters.html?highlight=filters#skimage.filters.gaussian) provides a good way to deal with this."
    ]
   },
   {
@@ -100,7 +100,7 @@
    "id": "1f426602-c445-4ba2-b176-0cde39554c62",
    "metadata": {},
    "source": [
-    "*Salt noise* changes random pixels to high values - such noise can originate from dead pixels of the detector hardware. The median filter provides a good way to deal with this"
+    "*Salt noise* changes random pixels to high values - such noise can originate from dead pixels of the detector hardware. The [median filter](https://scikit-image.org/docs/stable/api/skimage.filters.html?highlight=filters#skimage.filters.median) provides a good way to deal with this"
    ]
   },
   {
@@ -134,7 +134,7 @@
    "id": "e919dbfe-b73b-4ae2-a047-76b10e488b20",
    "metadata": {},
    "source": [
-    "Conversely, *pepper noise* can change single pixels to very low values, which can also originate from hardware isues. The median filter also provides a good option to deal with this type of noise."
+    "Conversely, *pepper noise* can change single pixels to very low values, which can also originate from hardware isues. The [median filter](https://scikit-image.org/docs/stable/api/skimage.filters.html?highlight=filters#skimage.filters.median) also provides a good option to deal with this type of noise."
    ]
   },
   {
@@ -169,7 +169,7 @@
    "id": "e1051565-e64b-4dce-a568-90595a4ce5d5",
    "metadata": {},
    "source": [
-    "The image background represents a type of noise that affects large areas of the image, which can orginate from heterogeneous lighting at a microscope or autofluorescence of fluorescent markers. The top-hat filter provides a suitable means to address this problem."
+    "The image background represents a type of noise that affects large areas of the image, which can orginate from heterogeneous lighting at a microscope or autofluorescence of fluorescent markers. The [top-hat](https://scikit-image.org/docs/stable/api/skimage.morphology.html?highlight=closing#skimage.morphology.white_tophat) filter provides a suitable means to address this problem."
    ]
   },
   {