Camera Settings

The parameter panel on the Camera page is used to set camera parameters. Click the Save button to save the parameters. Node-Camera initializes the camera with saved parameters on startup. Click the Reset button to restore the default settings. The parameter panel also provides switches for face detection and QR code recognition.

Camera parameter panel

Camera Parameters

• Resolution - Image resolution.

  Node-Camera supports the OV2640 image sensor, with a resolution range of 240x240~1600x1200. In addition to predefined resolutions, the firmware also allows users to customize a window. Select Custom Window from the Resolution drop-down list, and the custom window parameters will be displayed on the panel.

  

  Custom window parameters

  The physical resolution of the OV2640 image sensor is UXGA 1600x1200, which supports subsampling mode. It can sample the sensor data into image data with SVGA 800x600 or CIF 400x296 resolution. Select the sampling mode through the Sensor Size parameter to specify the sensor image size (sampled image size).

  After specifying the sensor image size, you can continue to set the required window area on the image. The window's position and size are defined by the Offset and Window Size parameters.

  

  Window definition

  After specifying the window area, you can set the Output Size parameter to scale down the window area to the desired output size.

  Finally, click the Set button to apply the settings.

  1. The window area should not go beyond the sensor image boundary, meaning the sum of window size and offset should not exceed the image's dimensions.
  2. Under certain window sizes, display issues like diagonal stripes may occur. Please try to fine-tune the size and offset.
  3. The output size should be less than or equal to the window size.

The remaining parameters of the camera are all conventional definitions, including:

Name	Description
Quality	Image quality (Lower values mean better quality)
Brightness	Brightness
Contrast	Contrast
Saturation	Saturation
Special Effect	Special Effect
AWB	Auto White Balance
AEC	Auto Exposure Control
AE Level	Auto Exposure Level
Exposure	Exposure
AEC DSP	Automatic Exposure Control DSP
AGC	Auto Gain Control
Gain Ceiling	Gain Ceiling
Raw GMA	Raw Gamma
Lens Correction	Lens Correction
H-Mirror	Horizontal Flip
V-Flip	Vertical Flip

Detection and Recognition

The Node-Camera firmware has built-in face detection and QR code recognition algorithms, and the switches for these algorithms are controlled by the camera parameter panel. The detection and recognition algorithm switches are not saved as camera settings.

• Face Detection

  The Face Detection switch controls the operation of the face detection algorithm. When face detection is turned on, the system automatically switches to QVGA 320x240 resolution. The face detection operates at around 3-5 FPS. When a face is detected, it will be marked with a box in the image, and the face's coordinates will be sent via the serial port. Output format:

  {"face": [x, y, width, height]}

• QR Code Scanning

  The QR Code Scanning switch controls the operation of the QR code recognition algorithm. When QR code recognition is turned on, the system automatically switches to QVGA 320x240 resolution and sets the image to grayscale mode. The QR code recognition operates at around 5-8 FPS. When a QR code is detected, the decoded result will be shown on the image, and also sent via the serial port (without any formatting).

  Node-Camera supports QR codes up to Version 20 standard (97x97), and does not support QR codes with special patterns.

  1. QR code version reference: https://www.qrcode.com/en/about/version.html
  2. Online QR code generator: https://www.qr-code-generator.com