Python Image Library PIL

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Python Image LibraryPIL

• 10/13/05

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PIL What is it?

• Pythonic library for
• Loading and Saving images (diverse formats)
• Scaling, cropping, compositing, transforms, bands
  (e.g. alpha channel)
• Drawing text and basic shapes
• Akin to the program GIMP (GIMP also has a nice
  python API called GIMP-Python)

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PIL - Examples

• Image resizing or format conversions
• Adding save/load support into your application
• Font support also handy
• Chart generation (also see PIDDLE piddle.sf.net)
• Thumbnail generation
• Watermarking or adding legend

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PIL API - Concepts

• Image from file or newly created
• gtgtgt import Image
• gtgtgt im Image.open(vacation.jpeg")
• gtgtgt newIm Image.new (RGBA, (640, 480), (255,
  0, 0))
• Format file format
• gtgtgt print im.mode, im.size, im.format
• RGB (1024, 768) JPEG
• gtgtgt im.save (vacation.png) OR
• gtgtgt im.save (vacation.png, PNG)

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PIL API - Concepts

• Resampling Filters
• NEAREST, BILINEAR, BICUBIC, ANTIALIAS
• gtgtgt smallIm im.resize ( (128, 128),
  Image.ANTIALIAS)
• Sizes tuple of width and height
• Bounding boxes tuples of x1, y1, x2, y2
• 0,0 is always upper left

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PIL API - Concepts

• Mode gray scale L, color RGBA RGB, etc.
• 1 (1-bit pixels, black and white, stored with one
  pixel per byte)
• L (8-bit pixels, black and white)
• P (8-bit pixels, mapped to any other mode using a
  colour palette)
• RGB (3x8-bit pixels, true colour)
• RGBA (4x8-bit pixels, true colour with
  transparency mask)
• CMYK (4x8-bit pixels, colour separation)
• YCbCr (3x8-bit pixels, colour video format)
• I (32-bit integer pixels)
• F (32-bit floating point pixels)
• Color specified as 32bit value, tuple, or
  string
• myColor (255, 0, 0, 128) full red, with 50
  alpha
• myColor 0x7f0000ff full red, with 50 alpha
• myColor 00ff00 web color
• myColor rgb (75, 0, 0)
• myColor hsl (0, 100, 50)

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PIL API - Concepts

• Bands the separate color channels
• gtgtgt bands im.split ()
• gtgtgt rIm bands 0
• gtgtgt aIm bands 3
• gtgtgt remadeImage Image.merge (RGBA, (rIm, gIm,
  bIm, aIm))
• gtgtgt grayscaleIm Image.open (myAlpha.gif)
• gtgtgt remadeImage myImage.putalpha (grayscaleIm)
  replace the alpha band

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PIL Slicing Dicing

• Thumbnails
• Modifies in-place
• Preserves aspect ratio
• gtgtgt myImage.thumbnail ((128, 128),
  Image.ANTIALIAS)
• Crop
• gtgtgt bounds (100, 100, 400, 400)
• gtgtgt cutoutIm myImage.crop (bounds)
• Paste

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PIL Slicing Dicing

• Blend/composite
• Rotate
• Transpose
• ROTATE_90/180/270, FLIP_TOP_BOTTOM,
  FLIP_LEFT_RIGHT
• gtgtgt fixedIm myImage.transpose (ROTATE_90)

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PIL - Drawing

• ImageDraw module creates drawing surface for
  image
• gtgtgt import Image, ImageDraw
• gtgtgt im Image.open(vacation.jpeg")
• gtgtgt drawSurface ImageDraw.Draw (im)
• gtgtgt import Image, ImageDraw
• gtgtgt im Image.open(vacation.jpeg")
• gtgtgt im.getpixel ( (4,4) )
• gtgtgt im.putpixel ( (4,4), (255,0,0))

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PIL - Drawing

• Basic methods of drawing surface
• chord arc pieslice (bounds, strtAng, endAng)
• ellipse (bounds)
• line (coordSeq)
• point (coordSeq)
• polygon (coordSeq)
• rectangle (bounds) first coord inclusive,
  second coord exclusvie
• Common optional args for these methods
• fillfillColor
• outlineoutlineColor

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PIL Drawing Text

• Text
• gtgtgt drawSurface ImageDraw.Draw (im)
• gtgtgt drawable.text ((10, 10), Hello,
  fill(255,0,0), fontNone)
• TrueType Font supportgt
• gtgtgt import ImageFont
• gtgtgt ttFont ImageFont.truetype (arial.ttf, 16)
• gtgtgt drawable.text ((10, 10), Hello,
  fill(255,0,0), fontttFont)

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References

• Python Image Library
• http//www.pythonware.com/products/pil/
• Other documentation sources
• PIL Handbook
• http//effbot.org/imagingbook/
• Nice pdf from New Mexico Tech
• http//www.nmt.edu/tcc/help/pubs/pil/

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• BMP
• BUFR (identify only)
• EPS (write-only)
• FITS (identify only)
• GIF
• GRIB (identify only)
• HDF5 (identify only)
• IM
• JPEG
• MPEG (identify only)
• MSP
• PALM (write only)
• PCX
• PDF (write only)
• PNG
• PPM
• TIFF
• WMF (identify only)
• XBM

• CUR (read only)
• DCX (read only) FLI, FLC (read only)
• FPX (read only)
• GBR (read only)
• GD (read only)
• ICO (read only)
• IMT (read only)
• IPTC/NAA (read only)
• MCIDAS (read only)
• MIC (read only)
• PCD (read only)
• PIXAR (read only)
• PSD (read only)
• SGI (read only)
• TGA (read only)
• WAL (read only)
• XPM (read only)