image-processor.class.ts

import * as cv from "opencv4nodejs-prebuilt";
import { Image } from "../../image.class";
import { Region } from "../../region.class";

function determineROI(img: Image, roi: Region): cv.Rect {
  return new cv.Rect(
    Math.min(Math.max(roi.left, 0), img.width),
    Math.min(Math.max(roi.top, 0), img.height),
    Math.min(roi.width, img.width - roi.left),
    Math.min(roi.height, img.height - roi.top));
}

export class ImageProcessor {
  /**
   * fromImageWithAlphaChannel should provide a way to create a library specific
   * image with alpha channel from an abstract Image object holding raw data and image dimension
   *
   * @param {Image} img The input Image
   * @param {Region} [roi] An optional Region to specify a ROI
   * @returns {Promise<any>} An image
   * @memberof VisionProviderInterface
   */
  public static async fromImageWithAlphaChannel(
    img: Image,
    roi?: Region,
  ): Promise<cv.Mat> {
    const mat = await new cv.Mat(img.data, img.height, img.width, cv.CV_8UC4).cvtColorAsync(cv.COLOR_BGRA2BGR);
    if (roi) {
      return mat.getRegion(determineROI(img, roi));
    } else {
      return mat;
    }
  }

  /**
   * fromImageWithoutAlphaChannel should provide a way to create a library specific
   * image without alpha channel from an abstract Image object holding raw data and image dimension
   *
   * @param {Image} img The input Image
   * @param {Region} [roi] An optional Region to specify a ROI
   * @returns {Promise<any>} An image
   * @memberof VisionProviderInterface
   */
  public static async fromImageWithoutAlphaChannel(
    img: Image,
    roi?: Region,
  ): Promise<cv.Mat> {
    const mat = new cv.Mat(img.data, img.height, img.width, cv.CV_8UC3);
    if (roi) {
      return mat.getRegion(determineROI(img, roi));
    } else {
      return mat;
    }
  }
}