`matchTemplate()` with transparency and opencv4nodejs

match_temp_transparency.js

// Gist made mainly for https://stackoverflow.com/questions/15459090/how-to-find-a-template-in-an-image-using-a-mask-or-transparency-with-opencv-an
// It's also where I've gotten the images from

// Require: Packages
const openCv = require('opencv4nodejs')

// Variables
const image = openCv.imread('stop_leaves.png')
// const image = openCv.imread('stop_moon.png')
// const image = openCv.imread('stop_mountain.png')
const template = openCv.imread('stop.png')

// Match with template as both template and mask parameter
// As of writing this file, opencv4nodejs only supports method 0 and 3 with a mask. I've had more success with 3
const minMax = image.matchTemplate(template, 3, template).minMaxLoc()

// Uncomment if you want to see the difference in probability without the mask
// const minMax = image.matchTemplate(template, 3).minMaxLoc()

// Log info
console.log(`Probability: ${minMax.maxVal}`)

// Draw a rectangle around found image
image.drawRectangle(
    new openCv.Rect(minMax.maxLoc.x, minMax.maxLoc.y, template.cols, template.rows),
    new openCv.Vec(0, 255, 0),
    2,
    openCv.LINE_8
)

// Show image in new window
openCv.imshow('Template matching with transparency', image)
openCv.waitKey()