Creating thumbnails (by resizing images) and cropping are most frequent works about images. This guide explains ways to deal with sizes of images.
Above all, to get the current size of the image check ~wand.image.Image.width and ~wand.image.Image.height properties:
pycon
>>> from urllib2 import urlopen >>> from wand.image import Image >>> f = urlopen('http://api.twitter.com/1/users/profile_image/hongminhee') >>> with Image(file=f) as img: ... width = img.width ... height = img.height ... >>> f.close() >>> width 48 >>> height 48
If you want to the pair of (~wand.image.Image.width, ~wand.image.Image.height), check ~wand.image.Image.size property also.
Note
These three properties are all readonly.
It scales an image into a desired size even if the desired size is larger than the original size. ImageMagick provides so many algorithms for resizing. The constant ~wand.image.FILTER_TYPES contains names of filtering algorithms.
- ImageMagick Resize Filters__
Demonstrates the results of resampling three images using the various resize filters and blur settings available in ImageMagick, and the file size of the resulting thumbnail images.
Image.resize() <wand.image.Image.resize> method takes width and height of a desired size, optional filter ('undefined' by default which means IM will try to guess best one to use) and optional blur (default is 1). It returns nothing but resizes itself in-place.
pycon
>>> img.size (500, 600) >>> img.resize(50, 60) >>> img.size (50, 60)
To extract a sub-rectangle from an image, use the ~wand.image.Image.crop() method. It crops the image in-place. Its parameters are left, top, right, bottom in order.
pycon
>>> img.size (200, 300) >>> img.crop(10, 20, 50, 100) >>> img.size (40, 80)
It can also take keyword arguments width and height. These parameters replace right and bottom.
pycon
>>> img.size (200, 300) >>> img.crop(10, 20, width=40, height=80) >>> img.size (40, 80)
There is an another way to crop images: slicing operator. You can crop an image by [left:right, top:bottom] with maintaining the original:
pycon
>>> img.size (300, 300) >>> with img[10:50, 20:100] as cropped: ... print cropped.size ... (40, 80) >>> img.size (300, 300)