The ImageFilter module contains a number of pre-defined filters such as BLUR, CONTOUR, DETAIL, EDGE_ENHANCE, EMBOSS, SHARPEN, SMOOTH, etc. These filters can be used with the ```Image.filter()``` method. 

An example: 
``` 
from PIL import ImageFilter

im1 = im.filter(ImageFilter.BLUR)

im2 = im.filter(ImageFilter.MinFilter(3))
im3 = im.filter(ImageFilter.MinFilter)
```

University of Michigan - Ann Arbor

PIL provides a number of methods and modules that can be used to enhance images using
- Filters
- Point Operations
- Advanced enhancement

Image enhancement

https://pillow.readthedocs.io/en/stable/index.html

PIL/Pillow documentaion

Filters

The ```point()``` method can be used to translate the pixel of an image. This method can be combined with ```paste()``` to selectively modify an image. 

```
# split the image into individual bands
source = im.split()

R, G, B = 0, 1, 2

# select regions where red is less than 100
mask = source[R].point(lambda i: i < 100 and 255)

# process the green band
out = source[G].point(lambda i: i * 0.7)

# paste the processed band back, but only where red was < 100
source[G].paste(out, None, mask)

# build a new multiband image
im = Image.merge(im.mode, source)
```

Point Operations

The ImageEnhance module provides its own classes and functions that allows the user to adjust contrast, brightness, color balance, and sharpness. For all four functions, an enhancement factor of 1.0 gives the original image, and a factor of 0.0 gives a black/white/blurred image. 

For instance, to vary the sharpness of an image, use:
```
from PIL import ImageEnhance

enhancer = ImageEnhance.Sharpness(image)

for i in range(8):
    factor = i / 4.0
    enhancer.enhance(factor).show(f"Sharpness {factor:f}")
```

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