Are keys in the door?

I keep forgetting my keys on the outside of the door, and realize next morning I slept with the keys in the door. 😱

So, I decided to create this service to be able to send me notifications.

Requirements

• A security camera that supports RTSP (I use a TPlink/TAPO security camera)
• A device that can serve as a server
• FFmpeg installed

My setup

I have my security camera looking to the door:

Technical explanation

From the keys area, I defined an area where the keys should be visible, and for color comparaison, there is a control point to compare the colors with the keys area.

I get all pixels in that area and calculate the average color, ignoring those too close to the control point.

for y := startY; y >= endY; y-- {
    for x := startX; x <= endX; x++ {
        // Get the color of the pixel at the current position
        pixelColor := img.At(x, y)
        // Extract the RGB components
        r, g, b, _ := pixelColor.RGBA()

        if distance(r,g,b, controlPoint) < 10 {
            // Ignore colors too close to the control point
            // so later the comparator will be more precise.
            continue;	
        }
    }
}

Since the keys are darker than the door, the difference between the control point should be noticeable.

// Calculate the difference between the avg and the control point colors
difference := distance(
    avgR, avgB, avgG,
    controlPoint
)

// if the color from the control point differs more than 5 points,
// then the keys are there.
keysThere := difference > 5
return keysThere, nil

What I do with the bool?

For now, I just established a simple http server that prints a json with it 🤣

GET http://localhost:8090/status

{
  "keysInDoor": true
}