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Writing images
==============
You can write an :class:`~wand.image.Image` object into a file or a byte
string buffer (blob) as format what you want.
Convert images to JPEG
----------------------
If you wonder what is image's format, use :attr:`~wand.image.Image.format`
property.
.. sourcecode:: pycon
>>> image.format
'JPEG'
The :attr:`~wand.image.Image.format` property is writable, so you can convert
images by setting this property. ::
from wand.image import Image
with Image(filename='pikachu.png') as img:
img.format = 'jpeg'
# operations to a jpeg image...
If you want to convert an image without any changes of the original,
use :meth:`~wand.image.Image.convert()` method instead::
from wand.image import Image
with Image(filename='pikachu.png') as original:
with original.convert('jpeg') as converted:
# operations to a jpeg image...
pass
.. note::
Support for some of the formats are delegated to libraries or external
programs. To get a complete listing of which image formats are supported
on your system, use :program:`identify` command provided by ImageMagick:
.. sourcecode:: console
$ identify -list format
Save to file
------------
In order to save an image to a file, use :meth:`~wand.image.Image.save()`
method with the keyword argument ``filename``::
from wand.image import Image
with Image(filename='pikachu.png') as img:
img.format = 'jpeg'
img.save(filename='pikachu.jpg')
.. note::
The image format does not effect the file being saved, to save with a given colorspace use::
from wand.image import Image
with Image(filename='pikachu.jpg') as img:
img.format = 'jpeg'
img.save(filename='PNG24:pikachu.png')
Save to stream
--------------
You can write an image into a output stream (file-like object which implements
:meth:`~file.write()` method) as well. The parameter ``file`` takes a such
object (it also is the first positional parameter of
:meth:`~wand.image.Image.save()` method).
For example, the following code converts :file:`pikachu.png` image into
JPEG, gzips it, and then saves it to :file:`pikachu.jpg.gz`::
import gzip
from wand.image import Image
gz = gzip.open('pikachu.jpg.gz')
with Image(filename='pikachu.png') as img:
img.format = 'jpeg'
img.save(file=gz)
gz.close()
Get binary string
-----------------
Want just a binary string of the image? Use
:meth:`~wand.image.Image.make_blob()` method so::
from wand.image import Image
with image(filename='pikachu.png') as img:
img.format = 'jpeg'
jpeg_bin = img.make_blob()
There's the optional ``format`` parameter as well. So the above example code
can be simpler::
from wand.image import Image
with Image(filename='pikachu.png') as img:
jpeg_bin = img.make_blob('jpeg')
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