若問學習一個程式庫可有善法的耶？唯有多讀幾遍介面文件，嘗試使用而已乎！ PiCamera 已是少見手冊完備，範例周全之程式庫的哩，而且官方版之 Raspbian 預設安裝矣，直須從
2. Getting Started
Warning
Make sure your Pi is off while installing the camera module. Although it is possible to install the camera while the Pi is on, this isn’t good practice (if the camera is active when removed, it’s possible to damage it).
Connect your camera module to the CSI port on your Raspberry Pi; this is the long thin port adjacent to the HDMI socket. Gently lift the collar on top of the CSI port (if it comes off, don’t worry, you can push it back in but try to be more gentle in future!). Slide the ribbon cable of the camera module into the port with the blue side facing the Ethernet port (or where the Ethernet port would be if you’ve got a model A/A+).
Once the cable is seated in the port, press the collar back down to lock the cable in place. If done properly you should be able to easily lift the Pi by the camera’s cable without it falling out. The following illustrations show a well-seated camera cable with the correct orientation:
Make sure the camera module isn’t sat on anything conductive (e.g. the Pi’s USB ports or its GPIO pins). Now, apply power to your Pi. Once booted, start the Raspberry Pi Configuration utility and enable the camera module:
You will need to reboot after doing this (but this is one-time setup so you won’t need to do it again unless you re-install your operating system or switch SD cards). Once rebooted, start a terminal and try the following command:
raspistill -o image.jpg
If everything is working correctly, the camera should start, a preview from the camera should appear on the display and, after a 5 second delay it should capture an image (storing it as image.jpg) before shutting down the camera. Proceed to the Basic Recipes.
If something else happens, read any error message displayed and try any recommendations suggested by such messages. If your Pi reboots as soon as you run this command, your power supply is insufficient for running your Pi plus the camera module (and whatever other peripherals you have attached).
……
往下讀就好︰
3. Basic Recipes
The following recipes should be reasonably accessible to Python programmers of all skill levels. Please feel free to suggest enhancements or additional recipes.
3.1. Capturing to a file
Capturing an image to a file is as simple as specifying the name of the file as the output of whatever capture() method you require:
from time import sleep
from picamera import PiCamera
camera = PiCamera()
camera.resolution = (1024, 768)
camera.start_preview()
# Camera warm-up time
sleep(2)
camera.capture('foo.jpg')
Note that files opened by picamera (as in the case above) will be flushed and closed so that when the capture method returns, the data should be accessible to other processes.
3.2. Capturing to a stream
Capturing an image to a file-like object (a socket(), a io.BytesIO stream, an existing open file object, etc.) is as simple as specifying that object as the output of whatever capture() method you’re using:
from io import BytesIO from time import sleep from picamera import PiCamera # Create an in-memory stream my_stream = BytesIO() camera = PiCamera() camera.start_preview() # Camera warm-up time sleep(2) camera.capture(my_stream, 'jpeg')
Note that the format is explicitly specified in the case above. The BytesIO object has no filename, so the camera can’t automatically figure out what format to use.
然而好學者常會自問自答︰
5. Frequently Asked Questions (FAQ)
5.1. AttributeError: ‘module’ object has no attribute ‘PiCamera’
You’ve named your script picamera.py (or you’ve named some other script picamera.py. If you name a script after a system or third-party package you will break imports for that system or third-party package. Delete or rename that script (and any associated .pyc files), and try again.
5.2. Can I put the preview in a window?
No. The camera module’s preview system is quite crude: it simply tells the GPU to overlay the preview on the Pi’s video output. The preview has no knowledge (or interaction with) the X-Windows environment (incidentally, this is why the preview works quite happily from the command line, even without anyone logged in).
That said, the preview area can be resized and repositioned via the window attribute of the preview object. If your program can respond to window repositioning and sizing events you can “cheat” and position the preview within the borders of the target window. However, there’s currently no way to allow anything to appear on top of the preview so this is an imperfect solution at best.
努力貫通已學程式庫的吧︰
Python Imaging Library (PIL)
The Python Imaging Library (PIL) adds image processing capabilities to your Python interpreter. This library supports many file formats, and provides powerful image processing and graphics capabilities.
Status
The current free version is PIL 1.1.7. This release supports Python 1.5.2 and newer, including 2.5 and 2.6. A version for 3.X will be released later.
……
或應改為
About
Goals
The fork author’s goal is to foster and support active development of PIL through:
- Continuous integration testing via Travis CI
- Publicized development activity on GitHub
- Regular releases to the Python Package Index
License
Like PIL, Pillow is licensed under the MIT-like open source PIL Software License:
Software License
The Python Imaging Library (PIL) is
Copyright © 1997-2011 by Secret Labs AB
Copyright © 1995-2011 by Fredrik Lundh
By obtaining, using, and/or copying this software and/or its associated documentation, you agree that you have read, understood, and will comply with the following terms and conditions:
Permission to use, copy, modify, and distribute this software and its associated documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appears in all copies, and that both that copyright notice and this permission notice appear in supporting documentation, and that the name of Secret Labs AB or the author not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission.
SECRET LABS AB AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL SECRET LABS AB OR THE AUTHOR BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
Why a fork?
PIL is not setuptools compatible. Please see this Image-SIG post for a more detailed explanation. Also, PIL’s current bi-yearly (or greater) release schedule is too infrequent to accommodate the large number and frequency of issues reported.
What about PIL?
Note
Prior to Pillow 2.0.0, very few image code changes were made. Pillow 2.0.0 added Python 3 support and includes many bug fixes from many contributors.
As more time passes since the last PIL release, the likelihood of a new PIL release decreases. However, we’ve yet to hear an official “PIL is dead” announcement. So if you still want to support PIL, please report issues here first, then open corresponding Pillow tickets here.
Please provide a link to the first ticket so we can track the issue(s) upstream.
───《W!o+ 的《小伶鼬工坊演義》︰神經網絡【MNIST】一》
因而能學而時習之︰
Tutorial
Using the Image class
The most important class in the Python Imaging Library is the Image class, defined in the module with the same name. You can create instances of this class in several ways; either by loading images from files, processing other images, or creating images from scratch.
To load an image from a file, use the open() function in the Image module:
>>> from PIL import Image
>>> im = Image.open("lena.ppm")
If successful, this function returns an Image object. You can now use instance attributes to examine the file contents:
>>> from __future__ import print_function >>> print(im.format, im.size, im.mode) PPM (512, 512) RGB
The format attribute identifies the source of an image. If the image was not read from a file, it is set to None. The size attribute is a 2-tuple containing width and height (in pixels). The mode attribute defines the number and names of the bands in the image, and also the pixel type and depth. Common modes are “L” (luminance) for greyscale images, “RGB” for true color images, and “CMYK” for pre-press images.
If the file cannot be opened, an IOError exception is raised.
Once you have an instance of the Image class, you can use the methods defined by this class to process and manipulate the image. For example, let’s display the image we just loaded:
>>> im.show()