

The Python Imaging Library, known as `PIL` or `pillow` is a [Python](https://www.educative.io/answers/what-is-python) image-processing library. This library has powerful image processing capabilities, supports many file types, and is built for an effective internal representation of picture data.

There are many modules in the `PIL` library for different purposes. One such module is the `ImageFilter` module. As the name suggests, the `ImageFilter` module in `PIL` contains a pre-defined set of filters used for different purposes.

# The `MedianFilter` function

The median filter is used to pick the median value in a window of a given size. The `MedianFilter()` function creates a median filter. 

> Median is the middle term in a sorted array.

## Syntax

```
PIL.ImageFilter.MedianFilter(size=3)
```

## Parameter

- `size`: This is the window size.

## Coding example

from PIL import Image, ImageFilter

img = Image.open("/test.png").convert('RGB')

filter_size = 3

median_filter_img = img.filter(ImageFilter.MedianFilter(size=filter_size))

median_filter_img.save("output/median_filter_image.png")

python39


## Explanation

- **Line 1:** We import the `Image` and `ImageFilter` modules from `PIL`.
- **Line 3:** We load a test image into memory.
- **Line 5:** We define the filter size (or window).
- **Line 7:** We apply a median filter by invoking the `filter()` function on the image object. The median filter is passed as an argument to the `filter()` function.
- **Line 9:** We save the resulting image after applying the median filter to the disk.


## The `ModeFilter` function

The mode filter is used to pick the most occurring pixel value in a window of a given size. The `ModeFilter` function creates a mode filter. If no pixel value occurs more than twice, the original pixel value is preserved.


## Syntax

```
PIL.ImageFilter.ModeFilter(size=3)
```

## Parameter

- `size`:  This is the window size.


## Code:

from PIL import Image, ImageFilter

img = Image.open("/test.png").convert('RGB')

filter_size = 3

mode_filter_img = img.filter(ImageFilter.ModeFilter(size=filter_size))

mode_filter_img.save("output/mode_filter_image.png")

# 
## Explanation

- **Line 1:** We import the `Image` and `ImageFilter` modules from `PIL`.
- **Line 3:** We load a test image into memory.
- **Line 5:** We define the filter size (or window).
- **Line 7:** We apply a mode filter by invoking the `filter()` function on the image object. The mode filter is passed as an argument to the `filter()` function.
- **Line 9:** We save the resulting image after applying the mode filter to the disk.

test.tar.gz

What are median and mode filters in pillow in Python?

Median and mode filters in Pillow apply median and most frequent pixel value in windows of given size to process images.

What are median and mode filters in pillow in Python?

The MedianFilter function

Syntax

Parameter

Coding example

Explanation

The ModeFilter function

Syntax

Parameter

Code:

Explanation

The `MedianFilter` function

The `ModeFilter` function