The official home of the Python Programming Language. While Javascript is not essential for this website, your interaction with the content will be limited.
This page tells you how to setup a Python programming environment for your Mac OS X computer and provides a step-by-step guide for creating and running a simple 'Hello, world' Python program. All of the software is freely available on the Web. These instructions are for MacOS X 10.13 (High Sierra), but the instructions for other recent versions of Mac OS X are similar.
Overview
The Python programming environment required by this booksite consists of:
Downloading and Installing Python, IDLE, Tkinter, NumPy, and Pygame
Python 2 is bundled with Mac OS X. However, Python 3 is not. We recommend that you download and install Python 3, and use Python 3 exclusively when running programs associated with this booksite.
Perform these steps to download and install Python, IDLE, Tkinter, NumPy, and PyGame:
Perform these steps to test your installation:
Downloading and Installing the Booksite Library
Perform these steps to download and install the booksite library:
Perform these steps to test your installation of the booksite library:
Configuring IDLE
So far you've downloaded and installed all of the software that you'll need. You should perform one more step before creating your first program: configure the IDLE programming environment. Follow these instructions:
Composing Your First Program
Having installed Python, the Python standard libraries, IDLE, Tkinter, NumPy, Pygame, and the booksite libraries, and having configured IDLE, you are ready to compose your first Python program. Perform these instructions:
Running Your First Program
The final step is to run your program. It is possible to run some Python programs from within IDLE, but you should run the programs associated with this booksite directly from a Terminal window. To do that, perform these steps:
You now have installed and configured a reasonable Python environment, and have used it to compose and run a Python program. Congratulations! You are a Python programmer!
Downloading the Booksite Example Programs (optional)
We recommend that you download the booksite example programs, that is, the example Python programs that are presented incrementally throughout the booksite. Having done so, you can run those programs to help you learn about them. Perform these instructions:
Then perform these steps to test your download of the booksite example programs:
Downloading the Booksite Example Data (optional)
We recommend that you download the booksite example data, that is, the data files used by the booksite example programs that are presented incrementally throughout the booksite. Perform these instructions:
Downloading the Booksite Library: Part 2 (optional)
Previously on this page we described how to download and install the booksite library so Python can find it. Now we describe how to download the booksite library so you can find it — for the sake of studying the code that implements it, should you so desire. Perform these instructions:
We invite you to study the code that implements the booksite library. But don't be concerned if some of the code is cryptic. The code that implements the booksite library uses some features of Python that are beyond the scope of the textbook and this booksite.
Q & A
Q. Why do I get the error
ImportError: No module named stdio when I issue the command python program_that_uses_stdio.py ?
Download Pil For Python 3
A. You must issue the command
python3 program_that_uses_stdio.py , as described above.
Q. I downloaded files using my browser, but can't find them. Where are they?
A. Many browsers by default place downloaded files in the directory
/Users/yourusername/Downloads .
Q. How do I break out of an infinite loop when running my program from the Terminal application?
A. Type Ctrl-c. That is, while pressing the Ctrl key, type the c key.
Q. Must I use IDLE to create my Python programs? Can I use some other text editor?
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A. You need not use IDLE to create your Python programs; it is fine to use some other text editor. For example, it is reasonable to use the TextEdit editor that is bundled with Mac OS X. However if you do use some other text editor, then make sure you change its settings so it (1) uses a four-space indentation scheme, and (2) indents using spaces instead of tabs. The Wikipedia Comparison of text editors page provides summary descriptions of many text editors.
Pillow is an image processing library that has been forked from PIL (Python Image Library) that development has been stopped.
Pillow is the “friendly PIL fork” by Alex Clark and Contributors. PIL is the Python Imaging Library by Fredrik Lundh and Contributors.Pillow — Pillow (PIL Fork) 4.2.1 documentation
Although advanced image processing (face recognition, optical flow, etc.) like OpenCV can not be performed, simple image processing such as resizing (scaling), rotation, and trimming (partial cutout) can be performed.
Because Pillow is simpler and easier to understand than OpenCV, it is better to use it depending on the purpose.
This post describes the following contents.
See the following link for individual posts that explain various processes such as resizing and trimming.
Install
Pillow can be installed by
pip .
Pillow and PIL can not coexist. If you have installed both, you should uninstall both and reinstall only one.
If you do not know what is installed, you can check it as follows.
Uninstall is performed as follows.
Note that if you are using Python 3, you may have to use
pip3 instead of pip depending on your environment.
Basic usage
The official document is easy to understand.
Image loading, processing, saving
Read image file. Note that the name of the package to import is
PIL , not Pillow .
Get meta information such as format, size (width, height), mode etc. The size is expressed by
(width, height) .
Get minimum value and maximum value of each color of RGB.
Get the pixel value of the specified coordinate. The coordinate origin
(0, 0) is upper left.
As an example, processing of gray scale conversion (
convert('L') ), rotation by 90 degrees (rotate(90) ), and Gaussian blur (filter() ) is performed.
Display images with OS default software.
Save the image.
When saving with
save() , the parameters differ depending on the extension. See Image file format for details. In the case of jpg, you can specify the quality with the parameter quality . The default is 75 for 1 (lowest) to 95 (highest).
The original image and the image after processing are as follows.
Drawing
You can also draw figures.
Use ImageDraw Module. See also the following post for details.
First, create a solid image. Specify the size in the second argument and RGB colors in the third argument.
Specify the
Image object as an argument and create a Draw object.
Draw straight line, rectangle and ellipse.
Draw text with specified font.
The result is as follow.
In this example, a solid image is generated first, but it is also possible to read an image file and draw figures and text on it.
Other processing example
Here are some examples of image processing using Pillow (PIL). For details and sample code, refer to the posts linked.
Paste another image into the image
Paste another image on the background image.
In addition to rectangles, it is also possible to cut out and paste in any shape such as a circle using a mask image.
Composite two images
Composite two images of the same size.
It can be cut out and combined into an arbitrary figure using a mask image. A gradation image can be used as a mask to create an image that changes gradually.
Concatenate multiple images
Multiple images can be arranged vertically or horizontally to create a concatenated image.
![]() Create transparent png image
Create a transparent png image with an alpha channel.
This too can be masked in any shape.
Pil Python 3
Negative / positive inversion (invert pixel value)
A negative-positive inverted image (image with inverted pixel values) is generated.
Create circular or square thumbnail images
Create thumbnail images from large images.
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You can cut out the center, add margins to make it any size, or make it circular. It is also possible to process multiple images at once.
Create animated gifPython 3.7 Pil
You can create animated gif image as well as jpg and png.
Pil For Python 3.6
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