How to Design an Invisibility Cloak Using MATLAB and Simulink
Creating an invisibility cloak may sound like science fiction, but with the power of MATLAB and Simulink, it’s possible to simulate a surprisingly realistic illusion using straightforward image processing methods. This illusion is achieved by detecting a specific color in a video stream—like a bright orange cloak—and replacing that area with a pre-captured background image. As a result, the cloak appears to vanish, making it seem like the person wearing it is invisible. The technique is built on three main concepts: color-based thresholding, image segmentation, and real-time video manipulation. By applying these principles, we can isolate the cloak from the live video and replace only that portion with background pixels, effectively blending it into the surroundings. The process involves setting up a stable background image, tuning the system to detect the cloak’s color, and manipulating the live camera feed using Simulink’s visual modeling environment. Each step requires precise control and understanding of image processing techniques, making this project an excellent way to sharpen practical skills. For students working on related projects or those needing help with Simulink assignment tasks involving image manipulation or real-time processing, this example provides a great foundation to learn and build upon.
Step 1 – Capturing the Background
The illusion starts with capturing a still image of the background. This image will later replace the pixels where the cloak appears. For this to work effectively, the camera must remain stationary and the background should not have any moving elements. After connecting your USB webcam and ensuring the necessary support packages are installed, initiate the webcam and capture the background using the following commands:
This image should be taken without any person or object in the camera frame. It will act as the reference background that fills in the cloak’s position during the illusion.
Step 2 – Tuning the Cloak Color
With the background image saved, the next step is to detect the specific cloak color. In this example, we use an orange cloth. MATLAB’s Color Thresholder App is a perfect tool for isolating the exact color. Launch it using:
colorThresholder
Inside the app, load an image of the cloak and adjust the HSV or RGB sliders until only the cloak’s color is selected. Export this mask, which marks the regions where the cloak appears in the video. This mask will be used to blend in the background image selectively.
To improve the accuracy, especially if the mask detects unwanted areas, you can use the Image Segmenter App to refine it:
imageSegmenter
This interactive tool allows for cleaning up the mask by manually editing detected regions. The final binary mask should have white pixels representing the cloak area and black pixels elsewhere.
Step 3 – Manipulating the Live Video Feed
Now that both the background and cloak mask are ready, the final step is to process the video stream in real time using Simulink. The cloak’s segmented area is replaced with background pixels, while the rest of the frame is preserved. This creates the invisibility effect. To do this, we use three sub-processes: revealing the background, obscuring the foreground, and combining the two.
Revealing the Background
The first image is created by multiplying the binary mask (representing the cloak) with the saved background image. This shows the background only in the cloak region, and leaves the rest of the frame black.
backgroundPortion = cloakMask .* backgroundImage;
This operation extracts only the background pixels corresponding to where the cloak is present, making it appear as though the cloak is transparent.
Obscuring the Foreground
Next, we take the current frame from the webcam feed and apply the inverse of the cloak mask. This hides the cloak while retaining all other parts of the frame. The operation ensures only non-cloak areas of the live video remain visible.
This step effectively removes the cloak from the live video, clearing the way to blend it with the background image from the previous step.
Final Step – Adding the Images
With the two separate images ready—one containing the background only in cloak areas and the other containing everything else from the live feed—we simply add them together to produce the final frame.
finalOutput = backgroundPortion + foregroundPortion;
This merged frame is then displayed as the output, creating a convincing invisibility illusion where the cloak blends into the surroundings.
Creating the Simulink Model
To automate the entire process, we can use Simulink to build a real-time video processing system. Using blocks like From Video Device, Color Space Conversion, Thresholding, Logical Operator, and Image Addition, we recreate all the steps above in a visual flow.
Simulink’s drag-and-drop environment is especially helpful for users who prefer working with models rather than writing full code. The webcam feed is processed frame-by-frame, the cloak’s mask is applied, and the background is blended in real time using multipliers and logical operations. The final result is sent to the To Video Display block, completing the invisibility effect.
Testing and Running the Model
When testing the model, make sure to use a well-lit and controlled environment. The cloak should be a solid, vibrant color (such as bright orange, red, or green) that doesn't appear anywhere else in the frame. Uniform lighting is important to ensure the cloak's color remains consistent across frames. Keep the camera and background still to avoid glitches or mismatched overlays. Once everything is configured, run the Simulink model and watch the cloak disappear from the video display.
Key Assumptions of the Algorithm
To ensure the cloak illusion works properly, a few key assumptions are made. The webcam must remain fixed in position, and the background should be completely static throughout the process. Any movement in the background can disrupt the illusion. Also, lighting should be constant—shadows or changes in brightness can interfere with accurate color detection. The color of the cloak must be distinct and not shared with any other object in the frame. These assumptions simplify the thresholding process and improve overall performance of the effect.
Applications and Learning Outcomes
Beyond just a fun project, this invisibility cloak simulation provides hands-on experience with real-time video processing, color space transformations, image segmentation, logical operations on binary masks, and Simulink modeling. It’s a creative way to reinforce essential concepts in computer vision and digital image processing. Students and beginners can explore how math and logic work together to manipulate images, frame-by-frame, in a meaningful and visually impressive way.
Final Thoughts
Designing an invisibility cloak illusion using MATLAB and Simulink is a fun and hands-on way to explore the fundamentals of image processing. It combines creativity, logic, and coding into a single engaging project that not only entertains but also teaches valuable technical skills. By using simple techniques like color segmentation and background replacement, this project allows students to simulate a disappearing effect in real time using just a webcam and a bright-colored cloak.
The best part is that the concept is easy to grasp and doesn't require advanced programming knowledge, making it suitable for beginners and enthusiasts alike. This kind of project is also a great starting point for students looking to understand more about real-time video processing and model-based design. It’s ideal for coursework, personal exploration, or as a mini-project to enhance your understanding of MATLAB’s powerful toolboxes.
If you're stuck or unsure how to proceed, seeking help with MATLAB assignment can be incredibly useful. With the right guidance, what seems like a complex simulation becomes an achievable and rewarding experience. So whether you're working on this for fun or as part of your academic journey, launch MATLAB, grab that bright cloak, and step into the world of invisibility illusions!