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Reading an Image in MATLAB Online

Published in MATLAB Image Processing 3 mins read

Here is how to read an image in MATLAB Online:

You can read an image in MATLAB Online using the imread function.

Reading an image is a fundamental task in image processing. In MATLAB Online, you typically use the imread function to load image data into a variable. This process is straightforward and can be done within a script or the command window, often starting in a Live Script.

Steps to Read an Image

  1. Open MATLAB Online: Access MATLAB through your web browser.

  2. Open a Script or Live Script: While you can use the Command Window, a Live Script is a great way to combine code, output, and formatted text. The reference suggests starting with "Open Live Script. Read a sample image."

  3. Use the imread function: This function reads an image file into a MATLAB array. The syntax is variableName = imread("filename");. Replace "filename" with the path to your image file.

    • Example: As shown in the reference, you can read a sample image like this:
      A = imread("ngc6543a. jpg");

      This command reads the image file named "ngc6543a. jpg" and stores the image data in the variable A.

  4. Understand the Output: The imread function returns the image data as a multidimensional array.

    • For a color image, it returns an M-by-N-by-3 array, where M is the number of rows (height), N is the number of columns (width), and 3 represents the red, green, and blue color channels.
    • As noted in the reference, the imread function for a color image like "ngc6543a. jpg" "returns a 650-by-600-by-3 array of type uint8". uint8 is a common data type for image pixels, representing values from 0 to 255.

  5. Display the Image (Optional but Recommended): To view the image you've read, you can use functions like image or imshow.

    • Example: The reference suggests using the image function:
      image(A)

      This command displays the image data stored in the variable A in a figure window or within the Live Script output. imshow(A) is another commonly used function specifically designed for displaying images, often handling scaling and aspect ratios automatically.

Summary of Commands

Command Purpose Example
imread Reads an image file A = imread("image.jpg");
image or imshow Displays image data from an array image(A); or imshow(A);

By following these steps, you can successfully read and display images within the MATLAB Online environment, making it easy to start your image processing tasks.

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