Filters

In the pixel tutorial we treated the digital image as a mosaic of colored tiles. For this tutorial, we'll process images using filters that operate on the image as a whole. Or at least, that's what it looks like; the underlying software still "gets" and "puts" pixel values as we did in the pixel tutorial. The filters operate at a higher level of abstraction — we can think of the pixels as a lower level way of conceptualizing the digital image (lateral metaphors notwithstanding).

The filter scripts in this tutorial are all Python wrappers for Apple software in the Core Image system. I have used SWIG to wrap the Core Image code so that we can use these filters in our Python programs.

Installing the software and images

To install the module, you need to copy two files to the image directory we created. (These are new versions that include the filter code, so you need to copy them again if you've already installed them.)

Image.py _image.so

For all of the Python scripts below, you can click on the image to download the script. The filter name is a link to the Apple documentation of the Core Image filter wrapped by the Python code.

All the scripts below use one or more of the images below as input, so you will need to download them, too.


`duchamp.tif`	`puchamd.tif`	`pdm.tif`

Click on the filter names to read about what the arguments mean. Then change the argument values and rerun the script. Download some images from the Web and try modifying them.

ColorControls

from Image import * 
 
p = Image("duchamp.tif") 
p.ColorControls(1, .3, .5) 
 
p.save("ColorControls.jpg")

ExposureAdjust

from Image import * 
 
p = Image("duchamp.tif") 
p.ExposureAdjust(-1) 
 
p.save("ExposureAdjust.jpg")

GammaAdjust

from Image import * 
 
p = Image("duchamp.tif") 
p.GammaAdjust(2.2) 
 
p.save("GammaAdjust.jpg")

HueAdjust

from Image import * 
 
p = Image("duchamp.tif") 
p.HueAdjust(2) 
 
p.save("HueAdjust.jpg")

ColorInvert

from Image import * 
 
p = Image("duchamp.tif") 
p.ColorInvert() 
 
p.save("ColorInvert.jpg")

ColorPosterize

from Image import * 
 
p = Image("duchamp.tif") 
p.ColorPosterize(5) 
 
p.save("ColorPosterize.jpg")

SepiaTone

from Image import * 
 
p = Image("duchamp.tif") 
p.SepiaTone(.8) 
 
p.save("SepiaTone.jpg")

BumpDistortion

from Image import * 
 
p = Image("duchamp.tif") 
p.BumpDistortion(Vector(p.width/2,p.height/2), 120, 5) 
 
p.save("BumpDistortion.jpg")

CircularSplashDistortion

from Image import * 
 
p = Image("duchamp.tif") 
p.CircularSplashDistortion(Vector(p.width/2,p.height/2), 100) 
 
p.save("CircularSplashDistortion.jpg")

CircularWrap

from Image import * 
 
p = Image("duchamp.tif") 
p.CircularWrap(0, Vector(p.width/2,p.height/2), 50) 
 
p.save("CircularWrap.jpg")

HoleDistortion

from Image import * 
 
p = Image("duchamp.tif") 
p.HoleDistortion(Vector(p.width/2,p.height/2), 100) 
 
p.save("HoleDistortion.jpg")

PinchDistortion

from Image import * 
 
p = Image("duchamp.tif") 
p.PinchDistortion(Vector(p.width/2,p.height/2), 150, -2) 
 
p.save("PinchDistortion.jpg")

ColorMap

from Image import * 
 
p = Image("duchamp.tif") 
p.ColorMap(Image("puchamd.tif")) 
 
p.save("ColorMap.jpg")

UnsharpMask

from Image import * 
 
p = Image("duchamp.tif") 
p.UnsharpMask(.9, 5) 
 
p.save("UnsharpMask.jpg")

GaussianBlur

from Image import * 
 
p = Image("duchamp.tif") 
p.GaussianBlur(10) 
 
p.save("GaussianBlur.jpg")

MedianFilter

from Image import * 
 
p = Image("duchamp.tif") 
p.MedianFilter() 
 
p.save("MedianFilter.jpg")

MotionBlur

from Image import * 
 
p = Image("duchamp.tif") 
p.MotionBlur(15, 3.14159/6) 
 
p.save("MotionBlur.jpg")

NoiseReduction

from Image import * 
 
p = Image("duchamp.tif") 
p.NoiseReduction(.3, .8) 
 
p.save("NoiseReduction.jpg")

SharpenLuminance

from Image import * 
 
p = Image("duchamp.tif") 
p.SharpenLuminance(.2) 
 
p.save("SharpenLuminance.jpg")

Bloom

from Image import * 
 
p = Image("duchamp.tif") 
p.Bloom(5, .8) 
 
p.save("Bloom.jpg")

Edges

from Image import * 
 
p = Image("duchamp.tif") 
p.Edges(5) 
 
p.save("Edges.jpg")

Gloom

from Image import * 
 
p = Image("duchamp.tif") 
p.Gloom(8, .9) 
 
p.save("Gloom.jpg")

HeightFieldFromMask

from Image import * 
 
p = Image("duchamp.tif") 
p.HeightFieldFromMask(5) 
 
p.save("HeightFieldFromMask.jpg")

Pointillize

from Image import * 
 
p = Image("duchamp.tif") 
p.Pointillize(10, 0) 
 
p.save("Pointillize.jpg")

BlendWithMask

from Image import * 
 
p = Image("duchamp.tif") 
p.BlendWithMask(Image("puchamd.tif"), Image("pdm.tif")) 
 
p.save("BlendWithMask.jpg")

ColorBlendMode

from Image import * 
 
p = Image("duchamp.tif") 
p.ColorBlendMode(Image("puchamd.tif")) 
 
p.save("ColorBlendMode.jpg")

ColorBurnBlendMode

from Image import * 
 
p = Image("duchamp.tif") 
p.ColorBurnBlendMode(Image("puchamd.tif")) 
 
p.save("ColorBurnBlendMode.jpg")

ColorDodgeBlendMode

from Image import * 
 
p = Image("duchamp.tif") 
p.ColorDodgeBlendMode(Image("puchamd.tif")) 
 
p.save("ColorDodgeBlendMode.jpg")

DarkenBlendMode

from Image import * 
 
p = Image("duchamp.tif") 
p.DarkenBlendMode(Image("puchamd.tif")) 
 
p.save("DarkenBlendMode.jpg")

DifferenceBlendMode

from Image import * 
 
p = Image("duchamp.tif") 
p.DifferenceBlendMode(Image("puchamd.tif")) 
 
p.save("DifferenceBlendMode.jpg")

ExclusionBlendMode

from Image import * 
 
p = Image("duchamp.tif") 
p.ExclusionBlendMode(Image("puchamd.tif")) 
 
p.save("ExclusionBlendMode.jpg")

HardLightBlendMode

from Image import * 
 
p = Image("duchamp.tif") 
p.HardLightBlendMode(Image("puchamd.tif")) 
 
p.save("HardLightBlendMode.jpg")

HueBlendMode

from Image import * 
 
p = Image("duchamp.tif") 
p.HueBlendMode(Image("puchamd.tif")) 
 
p.save("HueBlendMode.jpg")

LightenBlendMode

from Image import * 
 
p = Image("duchamp.tif") 
p.LightenBlendMode(Image("puchamd.tif")) 
 
p.save("LightenBlendMode.jpg")

LuminosityBlendMode

from Image import * 
 
p = Image("duchamp.tif") 
p.LuminosityBlendMode(Image("puchamd.tif")) 
 
p.save("LuminosityBlendMode.jpg")

MultiplyBlendMode

from Image import * 
 
p = Image("duchamp.tif") 
p.MultiplyBlendMode(Image("puchamd.tif")) 
 
p.save("MultiplyBlendMode.jpg")

OverlayBlendMode

from Image import * 
 
p = Image("duchamp.tif") 
p.OverlayBlendMode(Image("puchamd.tif")) 
 
p.save("OverlayBlendMode.jpg")

SaturationBlendMode

from Image import * 
 
p = Image("duchamp.tif") 
p.SaturationBlendMode(Image("puchamd.tif")) 
 
p.save("SaturationBlendMode.jpg")

ScreenBlendMode

from Image import * 
 
p = Image("duchamp.tif") 
p.ScreenBlendMode(Image("puchamd.tif")) 
 
p.save("ScreenBlendMode.jpg")

SoftLightBlendMode

from Image import * 
 
p = Image("duchamp.tif") 
p.SoftLightBlendMode(Image("puchamd.tif")) 
 
p.save("SoftLightBlendMode.jpg")

Combinations

You can use more than one filter on a single image to combine their effects.

from Image import * 
 
p = Image("duchamp.tif") 
p.Edges(10) 
p.Pointillize(3, 0) 
p.SepiaTone(.5) 
 
p.save("Combined.jpg")

You can also process the picture with the pixel-level techniques we used before.

import Image 
 
p = Image.Image("duchamp.tif") 
 
xmin = int(round(p.width * .25)) 
xmax = int(round(p.width * .75)) 
ymin = int(round(p.height * .25)) 
ymax = int(round(p.height * .75)) 
 
for y in range(ymin, ymax + 1): 
    for x in range(xmin, xmax + 1): 
        r, g, b = p.get(x, y) 
        p.put(x, y, 1.0-r, 1.0-g, 1.0-b) 
 
p.GaussianBlur(3) 
 
p.save("Blursquare.jpg")

(There is currently a bug in my software that requires an image to be created from an image file for it be processed by the Python filters. This means that images made "from scratch" like the first set in the pixel tutorial cannot be filtered yet.)