snapshot

Capture RGB image from Camera

Since R2018b

Syntax

img = snapshot(cam)

[img,ts] = snapshot(cam)

Description

img = snapshot(cam) returns a still image in RGB format from the camera specified in the cam object.

[img,ts] = snapshot(cam) returns a still image in RGB format and the time stamp of the capture from the camera specified in the cam object.

Examples

Capture Images from a USB Webcam Connected to a NVIDIA Jetson Platform

You can connect from the MATLAB^® software to a USB camera connected to an NVIDIA^® platform and capture images from this camera.

Create a live hardware connection from the MATLAB software to the NVIDIA hardware by using the jetson function. To create a live hardware connection object, provide the host name or IP address, user name, and password of the target board. For example:

hwobj = jetson('jetson-board-name','ubuntu','ubuntu');

To find the web camera name, check the webcamlist property of the hwobj object.

hwobj.webcamlist

ans =

  1×1 cell array

    {'Microsoft® LifeCam Cinema(TM)'}

If this property is empty, then try reconnecting the USB webcam and run the following command. This command tries to scan the available webcams on the target when there is a addition or deletion.

updatePeripheralInfo(hwobj);

Create a webcam object, wcam using the name or the index number of the webcam list. If no webcam name or the index is specified, then it uses the default webcam. The wcam object has the following camera properties.

wcam = webcam(hwobj)

wcam = 

  webcam with properties:

                    Name: 'Microsoft® LifeCam Cinema(TM)'
              Resolution: '320x240'
    AvailableResolutions: {1×12 cell}

To display the images captured from webcam in MATLAB, use the following commands.

img = snapshot(wcam);
figure();
imagesc(img);
drawnow;

To change the resolution of the image capture, use the following command.

clear wcam;
wcam = webcam(hwobj,1,[1280 800])

You can use the AvailableResolutions property of the wcam object to get a cell array of the available resolutions for your camera.

Import and display a sequence of 50 snapshots on your host computer.

figure();
for ii = 1:50
    img = snapshot(wcam);
    imagesc(img);
    drawnow;
end

Input Arguments

cam — Connection to web camera

camera object | webcam object

Connection to a camera, specified as a camera or webcam object.

Example: mycam

Output Arguments

img — RGB image

m-by-n-by-3 numeric array

RGB image, returned as an m-by-n-by-3 numeric array with values in the range [0,255].

Data Types: uint8

ts — Timestamp of the snapshot

datetime object, in seconds

Timestamp of the snapshot, returned as a datetime object.

Version History

Introduced in R2018b