ImageFilter
Module¶
The ImageFilter
module contains definitions for a predefined set of
filters, which can be be used with the Image.filter()
method.
Example: Filter an image¶
from PIL import ImageFilter
im1 = im.filter(ImageFilter.BLUR)
im2 = im.filter(ImageFilter.MinFilter(3))
im3 = im.filter(ImageFilter.MinFilter) # same as MinFilter(3)
Filters¶
The current version of the library provides the following set of predefined image enhancement filters:
 BLUR
 CONTOUR
 DETAIL
 EDGE_ENHANCE
 EDGE_ENHANCE_MORE
 EMBOSS
 FIND_EDGES
 SHARPEN
 SMOOTH
 SMOOTH_MORE

class
PIL.ImageFilter.
GaussianBlur
(radius=2)¶ Gaussian blur filter.
Parameters: radius – Blur radius.

class
PIL.ImageFilter.
BoxBlur
(radius)¶ Blurs the image by setting each pixel to the average value of the pixels in a square box extending radius pixels in each direction. Supports float radius of arbitrary size. Uses an optimized implementation which runs in linear time relative to the size of the image for any radius value.
Parameters: radius – Size of the box in one direction. Radius 0 does not blur, returns an identical image. Radius 1 takes 1 pixel in each direction, i.e. 9 pixels in total.

class
PIL.ImageFilter.
UnsharpMask
(radius=2, percent=150, threshold=3)¶ Unsharp mask filter.
See Wikipedia’s entry on digital unsharp masking for an explanation of the parameters.
Parameters:  radius – Blur Radius
 percent – Unsharp strength, in percent
 threshold – Threshold controls the minimum brightness change that will be sharpened

class
PIL.ImageFilter.
Kernel
(size, kernel, scale=None, offset=0)¶ Create a convolution kernel. The current version only supports 3x3 and 5x5 integer and floating point kernels.
In the current version, kernels can only be applied to “L” and “RGB” images.
Parameters:  size – Kernel size, given as (width, height). In the current version, this must be (3,3) or (5,5).
 kernel – A sequence containing kernel weights.
 scale – Scale factor. If given, the result for each pixel is divided by this value. the default is the sum of the kernel weights.
 offset – Offset. If given, this value is added to the result, after it has been divided by the scale factor.

class
PIL.ImageFilter.
RankFilter
(size, rank)¶ Create a rank filter. The rank filter sorts all pixels in a window of the given size, and returns the rank’th value.
Parameters:  size – The kernel size, in pixels.
 rank – What pixel value to pick. Use 0 for a min filter,
size * size / 2
for a median filter,size * size  1
for a max filter, etc.

class
PIL.ImageFilter.
MedianFilter
(size=3)¶ Create a median filter. Picks the median pixel value in a window with the given size.
Parameters: size – The kernel size, in pixels.

class
PIL.ImageFilter.
MinFilter
(size=3)¶ Create a min filter. Picks the lowest pixel value in a window with the given size.
Parameters: size – The kernel size, in pixels.

class
PIL.ImageFilter.
MaxFilter
(size=3)¶ Create a max filter. Picks the largest pixel value in a window with the given size.
Parameters: size – The kernel size, in pixels.

class
PIL.ImageFilter.
ModeFilter
(size=3)¶ Create a mode filter. Picks the most frequent pixel value in a box with the given size. Pixel values that occur only once or twice are ignored; if no pixel value occurs more than twice, the original pixel value is preserved.
Parameters: size – The kernel size, in pixels.