[树莓派] : 如何用树莓派利用摄像头进行简单的人脸识别【how to use IR camera +raspberrypi 3b+ in python】

# how to use IR camera +raspberrypi 3b+ in python:

1.connect the camera module: shut down the respberrypi power,connect the camera

2.open the ir camera： use python IDE

Introduction

What you will need

Raspberry Pi computer with a Camera Module port

Raspberry Pi Camera Module

Connect the Camera Module

How to control the Camera Module via the command line

How to control the Camera Module with Python code

Recording video with Python code

How to change the image settings and add image effects

Set the image resolution

Add text to your image

Change the look of the added text

Change the brightness of the preview

Change the contrast of the preview

Introduction

Learn how to connect the Raspberry Pi Camera Module to your Raspberry Pi and take pictures, record video, and apply image effects.

What you will need

Raspberry Pi computer with a Camera Module port

All current models of Raspberry Pi have a port for connecting the Camera Module.

Note: If you want to use a Raspberry Pi Zero, you need a Camera Module ribbon cable that fits the Raspberry Pi Zero’s smaller Camera Module port.

Raspberry Pi Camera Module

Connect the Camera Module

Ensure your Raspberry Pi is turned off.

Locate the Camera Module port
Gently pull up on the edges of the port’s plastic clip
Insert the Camera Module ribbon cable; make sure the cable is the right way round
Push the plastic clip back into place

Start up your Raspberry Pi.
Go to the main menu and open the Raspberry Pi Configuration tool.
Select the Interfaces tab and ensure that the camera is enabled:
Reboot your Raspberry Pi.

How to control the Camera Module via the command line

Now your Camera Module is connected and the software is enabled, try out the command line tools raspistill and raspivid.

Open a terminal window by clicking the black monitor icon in the taskbar:

Type in the following command to take a still picture and save it to the Desktop:

raspistill -o Desktop/image.jpg

Press Enter to run the command.

When the command runs, you can see the camera preview open for five seconds before a still picture is taken.

Look for the picture file icon on the Desktop, and double-click the file icon to open the picture.

By adding different options, you can set the size and look of the image the raspistill command takes.

For example, add -h and -w to change the height and width of the image:

raspistill -o Desktop/image-small.jpg -w 640 -h 480

Now record a video with the Camera Module by using the following raspivid command:

raspivid -o Desktop/video.h264

In order to play the video file, double-click the video.h264 file icon on the Desktop to open it in VLC Media Player.

How to control the Camera Module with Python code

The Python picamera library allows you to control your Camera Module and create amazing projects.

You should see the camera preview open for five seconds, and then a still picture should be captured. As the picture is being taken, you can see the preview briefly adjust to a different resolution.

Your new image should be saved to the Desktop.

The camera should take one picture every five seconds. Once the fifth picture is taken, the preview closes.

Your Raspberry Pi should open a preview, record 5 seconds of video, and then close the preview.

Open a Python 3 editor, such as Thonny Python IDE:
Open a new file and save it as camera.py.

Note: it’s important that you never save the file as picamera.py.

Enter the following code:

from picamera import PiCamera
from time import sleepcamera = PiCamera()camera.start_preview()
sleep(5)
camera.stop_preview()

Save and run your program. The camera preview should be shown for five seconds and then close again.
If your preview is upside-down, you can rotate it by 180 degrees with the following code:
```
camera = PiCamera()
camera.rotation = 180
```
You can rotate the image by 90, 180, or 270 degrees. To reset the image, set rotation to 0 degrees.
Make the camera preview see-through by setting an alpha level:
```
camera.start_preview(alpha=200)
```
The alpha value can be any number between 0 and 255.
It’s best to make the preview slightly see-through so you can see whether errors occur in your program while the preview is on.
Now use the Camera Module and Python to take some still pictures.
Amend your code to add a camera.capture() line:
```
camera.start_preview()
sleep(5)
camera.capture('/home/pi/Desktop/image.jpg')
camera.stop_preview()
```
Note: it’s important to sleep for at least two seconds before capturing an image, because this gives the camera’s sensor time to sense the light levels.
Run the code.
Now add a loop to take five pictures in a row:
```
camera.start_preview()
for i in range(5):sleep(5)camera.capture('/home/pi/Desktop/image%s.jpg' % i)
camera.stop_preview()
```
The variable i counts how many times the loop has run, from 0 to 4. Therefore, the images get saved as image0.jpg, image1.jpg, and so on.
Look at your Desktop to find the five new pictures.
- Run the code again and hold the Camera Module in position.
- Recording video with Python code
  
  Now record a video!
- Amend your code to remove capture() and instead add start_recording() and stop_recording()
  
  Your code should look like this now:
```
camera.start_preview()
camera.start_recording('/home/pi/Desktop/video.h264')
sleep(5)
camera.stop_recording()
camera.stop_preview()
```
- Run the code.

How to change the image settings and add image effects

The Python picamera software provides a number of effects and configurations to change how your images look.

Note: some settings only affect the preview and not the captured image, some affect only the captured image, and many others affect both.

Set the image resolution

You can change the resolution of the image that the Camera Module takes.

By default, the image resolution is set to the resolution of your monitor. The maximum resolution is 2592×1944 for still photos, and 1920×1080 for video recording.

Use the following code to set the resolution to maximum and take a picture.

Note: you also need to set the frame rate to 15 to enable this maximum resolution.

camera.resolution = (2592, 1944)
camera.framerate = 15
camera.start_preview()
sleep(5)
camera.capture('/home/pi/Desktop/max.jpg')
camera.stop_preview()

The minimum resolution is 64×64.

Add text to your image

You can add text to your image using the command annotate_text.

Change the look of the added text

It’s also possible to change the text colour.

Change the brightness of the preview

You can change how bright the preview appears. The default brightness is 50, and you can set it to any value between 0 and 100.

Change the contrast of the preview

Similarly to the preview brightness, you can change the contrast of the preview.

The default effect is none.

本篇文章转载自：https://projects.raspberrypi.org/en/projects/getting-started-with-picamera

更多请关注“树莓派官网”：https://projects.raspberrypi.org/en

Try taking a picture with the minimum resolution.

Run this code to try it:

camera.start_preview()
camera.annotate_text = "Hello world!"
sleep(5)
camera.capture('/home/pi/Desktop/text.jpg')
camera.stop_preview()

Set the text size with the following code:
```
camera.annotate_text_size = 50
```
You can set the text size to anything between 6 to 160. The default size is 32.
First of all, add Color to your import line at the top of the program:
```
from picamera import PiCamera, Color
```

Then below the import line, amend the rest of your code so it looks like this:

camera.start_preview()
camera.annotate_background = Color('blue')
camera.annotate_foreground = Color('yellow')
camera.annotate_text = " Hello world "
sleep(5)
camera.stop_preview()

Run the following code to try this out:

camera.start_preview()
camera.brightness = 70
sleep(5)
camera.capture('/home/pi/Desktop/bright.jpg')
camera.stop_preview()

The following loop adjusts the brightness and also adds text to display the current brightness level:

camera.start_preview()
for i in range(100):camera.annotate_text = "Brightness: %s" % icamera.brightness = isleep(0.1)
camera.stop_preview()

Run the following code to try this out:

camera.start_preview()
for i in range(100):camera.annotate_text = "Contrast: %s" % icamera.contrast = isleep(0.1)
camera.stop_preview()

Pick an image effect and try it out:

camera.start_preview()
camera.image_effect = 'colorswap'
sleep(5)
camera.capture('/home/pi/Desktop/colorswap.jpg')
camera.stop_preview()

Run this code to loop over all the image effects with camera.IMAGE_EFFECTS:

camera.start_preview()
for effect in camera.IMAGE_EFFECTS:camera.image_effect = effectcamera.annotate_text = "Effect: %s" % effectsleep(5)
camera.stop_preview()