S13-Words-for-the-Future-notebooks/working-with-images/PIL-basics.ipynb

PIL(low) talk¶

The "classic" Python Image Library (or PIL) is described in the (classic) handbook: http://www.effbot.org/imagingbook/pil-index.htm

In fact, the current library that people tend to use is called Pillow, but as a "friendly fork" it tries to acts just like the old PIL library, so you don't even notice (and your code still uses the name PIL). The Pillow project also maintains it's own documenation at:

https://pillow.readthedocs.io/en/stable/reference/index.html

In [1]:

from PIL import Image

In [3]:

im = Image.open("a.jpg")

In [4]:

im

Out[4]:

In [6]:

im = Image.open("cyber.jpg")

In [7]:

im.size

Out[7]:

(500, 488)

In [8]:

im.mode

Out[8]:

'RGB'

In [9]:

im.thumbnail( (320, 320) )

In [10]:

im.size

Out[10]:

(320, 312)

In [11]:

im

Out[11]:

In [12]:

from urllib.request import urlopen

In [13]:

f = urlopen("https://upload.wikimedia.org/wikipedia/commons/1/10/NOLAPunchCards1938.jpg")

In [14]:

key2 = Image.open(f)

In [15]:

key2.size

Out[15]:

(600, 458)

In [21]:

key2.convert("1")

Out[21]:

In [18]:

key2.convert?

Signature: key2.convert(mode=None, matrix=None, dither=None, palette=0, colors=256)
Docstring:
Returns a converted copy of this image. For the "P" mode, this
method translates pixels through the palette.  If mode is
omitted, a mode is chosen so that all information in the image
and the palette can be represented without a palette.

The current version supports all possible conversions between
"L", "RGB" and "CMYK." The **matrix** argument only supports "L"
and "RGB".

When translating a color image to greyscale (mode "L"),
the library uses the ITU-R 601-2 luma transform::

    L = R * 299/1000 + G * 587/1000 + B * 114/1000

The default method of converting a greyscale ("L") or "RGB"
image into a bilevel (mode "1") image uses Floyd-Steinberg
dither to approximate the original image luminosity levels. If
dither is NONE, all values larger than 128 are set to 255 (white),
all other values to 0 (black). To use other thresholds, use the
:py:meth:`~PIL.Image.Image.point` method.

When converting from "RGBA" to "P" without a **matrix** argument,
this passes the operation to :py:meth:`~PIL.Image.Image.quantize`,
and **dither** and **palette** are ignored.

:param mode: The requested mode. See: :ref:`concept-modes`.
:param matrix: An optional conversion matrix.  If given, this
   should be 4- or 12-tuple containing floating point values.
:param dither: Dithering method, used when converting from
   mode "RGB" to "P" or from "RGB" or "L" to "1".
   Available methods are NONE or FLOYDSTEINBERG (default).
   Note that this is not used when **matrix** is supplied.
:param palette: Palette to use when converting from mode "RGB"
   to "P".  Available palettes are WEB or ADAPTIVE.
:param colors: Number of colors to use for the ADAPTIVE palette.
   Defaults to 256.
:rtype: :py:class:`~PIL.Image.Image`
:returns: An :py:class:`~PIL.Image.Image` object.
File:      ~/.local/lib/python3.7/site-packages/PIL/Image.py
Type:      method

In [19]:

key2.thumbnail((1024, 1024))

In [22]:

key2.save("keypunch.png")

In [36]:

key3 = Image.open( urlopen("https://upload.wikimedia.org/wikipedia/commons/thumb/4/48/IBM26.jpg/1024px-IBM26.jpg") )

In [37]:

key3.size

Out[37]:

(1024, 683)

In [25]:

key3.convert("1", dither=Image.NONE)

Out[25]:

In [35]:

key3

In [38]:

key3.convert("L")

Out[38]:

In [33]:

#key3 = key3.thumbnail((64, 64))

In [39]:

key3 is None

Out[39]:

False

In [40]:

from PIL import ImageDraw

In [41]:

key3.save("keypunch_gray.png")

In [42]:

key2.convert?

Signature: key2.convert(mode=None, matrix=None, dither=None, palette=0, colors=256)
Docstring:
Returns a converted copy of this image. For the "P" mode, this
method translates pixels through the palette.  If mode is
omitted, a mode is chosen so that all information in the image
and the palette can be represented without a palette.

The current version supports all possible conversions between
"L", "RGB" and "CMYK." The **matrix** argument only supports "L"
and "RGB".

When translating a color image to greyscale (mode "L"),
the library uses the ITU-R 601-2 luma transform::

    L = R * 299/1000 + G * 587/1000 + B * 114/1000

The default method of converting a greyscale ("L") or "RGB"
image into a bilevel (mode "1") image uses Floyd-Steinberg
dither to approximate the original image luminosity levels. If
dither is NONE, all values larger than 128 are set to 255 (white),
all other values to 0 (black). To use other thresholds, use the
:py:meth:`~PIL.Image.Image.point` method.

When converting from "RGBA" to "P" without a **matrix** argument,
this passes the operation to :py:meth:`~PIL.Image.Image.quantize`,
and **dither** and **palette** are ignored.

:param mode: The requested mode. See: :ref:`concept-modes`.
:param matrix: An optional conversion matrix.  If given, this
   should be 4- or 12-tuple containing floating point values.
:param dither: Dithering method, used when converting from
   mode "RGB" to "P" or from "RGB" or "L" to "1".
   Available methods are NONE or FLOYDSTEINBERG (default).
   Note that this is not used when **matrix** is supplied.
:param palette: Palette to use when converting from mode "RGB"
   to "P".  Available palettes are WEB or ADAPTIVE.
:param colors: Number of colors to use for the ADAPTIVE palette.
   Defaults to 256.
:rtype: :py:class:`~PIL.Image.Image`
:returns: An :py:class:`~PIL.Image.Image` object.
File:      ~/.local/lib/python3.7/site-packages/PIL/Image.py
Type:      method

In [46]:

import aalib

---------------------------------------------------------------------------
ModuleNotFoundError                       Traceback (most recent call last)
<ipython-input-46-912cb9847582> in <module>
----> 1 import aalib

ModuleNotFoundError: No module named 'aalib'

In [ ]:

import aalib

In [44]:

screen = aalib.AsciiScreen(width=640, height=480)

---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-44-f44aedee4649> in <module>
----> 1 screen = aalib.AsciiScreen(width=640, height=480)

NameError: name 'aalib' is not defined

In [47]:

f = urlopen('https://www.python.org/static/favicon.ico')

In [48]:

im = Image.open(f)

In [49]:

im

Out[49]:

In [50]:

im = im.convert('L').resize(screen.virtual_size)

---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-50-235f2c5973fa> in <module>
----> 1 im = im.convert('L').resize(screen.virtual_size)

NameError: name 'screen' is not defined

In [ ]:

im

In [ ]:

screen.virtual_size

In [ ]:

screen.put_image((0, 0), im)

In [ ]:

print (screen.render())

In [ ]:

resized = key2.convert("L").resize(screen.virtual_size)
screen.put_image((0, 0), resized)

In [ ]:

screen.render()

In [ ]:

resized

In [ ]: