Update Image Example

update_image_example.js

/**
 * Generate a random color
 */
const getRandomColor = () => new cv.Vec(Math.random() * 255, Math.random() * 255, Math.random() * 255);

/**
 * Returns a function that, for each prediction, draws a rect area with rndom color
 * @param {Arry} predictions Array of predictions
 */
const makeDrawClassDetections = (predictions) => (drawImg, getColor, thickness = 2) => {
  predictions
    .forEach((p) => {
      let color = getColor()
      let confidence = p.confidence
      let rect = p.rect
      let className = classes[p.classIndex]
      drawRect(className, confidence, drawImg, rect, color, { thickness })
    })
  return drawImg
}

/*
  Take the original image and add rectanges on predictions.
  Write it to a new file.
 */
const updateImage = (imagePath, img, predictions) => {
  // get the filename and replace last occurrence of '.' with '_classified.'
  const filename = imagePath.replace(/^.*[\\\/]/, '').replace(/.([^.]*)$/,`_classified_${dataFile}_${confidence * 100.0}.` + '$1')

  // get function to draw rect around predicted object
  const drawClassDetections = makeDrawClassDetections(predictions);

  // draw a rect around predicted object
  drawClassDetections(img, getRandomColor);

  // write updated image to current directory
  cv.imwrite('./' + filename, img)
}

// draw a rect and label in specified area
/**
 * 
 * @param {String} className Predicted class name (identified object)
 * @param {Number} confidence The confidence level (ie: .80 = 80%)
 * @param {Object} image The image
 * @param {Object} rect The rect area
 * @param {Object} color The color to use
 * @param {Object} [opts={ thickness: 2 }] Options (currently only supports thikness)
 */
const drawRect = (className, confidence, image, rect, color, opts = { thickness: 2 }) => {
  let level = Math.round(confidence * 100.0)
  image.drawRectangle(
    rect,
    color,
    opts.thickness,
    cv.LINE_8
  )
  // draw the label (className and confidence level)
  let label = className + ': ' + level
  image.putText(label, new cv.Point2(rect.x, rect.y + 20), cv.FONT_ITALIC, .65, color, 2)
}