Created image-processor

Author: s1hofmann

lib/provider/opencv/image-processor.class.spec.ts

@@ -0,0 +1,39 @@
+import { resolve } from "path";
+import { ImageProcessor } from "./image-processor.class";
+import { ImageReader } from "./image-reader.class";
+
+describe("ImageProcessor", () => {
+  it("should allow to create a cv.Mat from an Image with alpha channel, alpha channel is dropped", async () => {
+    // GIVEN
+    const imageReader = new ImageReader();
+    const imagePath = resolve(__dirname, "./__mocks__/alpha_channel.png");
+    const image = await imageReader.load(imagePath);
+
+    // WHEN
+    const mat = await ImageProcessor.fromImageWithAlphaChannel(image);
+
+    // THEN
+    expect(image.hasAlphaChannel).toBeTruthy();
+    expect(mat.channels).toEqual(3);
+    expect(mat.rows).toEqual(image.height);
+    expect(mat.cols).toEqual(image.width);
+    expect(mat.empty).toBeFalsy();
+  });
+
+  it("should allow to create a cv.Mat from an Image without alpha channel", async () => {
+    // GIVEN
+    const imageReader = new ImageReader();
+    const imagePath = resolve(__dirname, "./__mocks__/mouse.png");
+    const image = await imageReader.load(imagePath);
+
+    // WHEN
+    const mat = await ImageProcessor.fromImageWithoutAlphaChannel(image);
+
+    // THEN
+    expect(image.hasAlphaChannel).toBeFalsy();
+    expect(mat.channels).toEqual(3);
+    expect(mat.rows).toEqual(image.height);
+    expect(mat.cols).toEqual(image.width);
+    expect(mat.empty).toBeFalsy();
+  });
+});

lib/provider/opencv/image-processor.class.ts

@@ -0,0 +1,47 @@
+import * as cv from "opencv4nodejs";
+import { Image } from "../../image.class";
+import { Region } from "../../region.class";
+
+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(new cv.Rect(roi.left, roi.top, roi.width, roi.height));
+    } 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(new cv.Rect(roi.left, roi.top, roi.width, roi.height));
+    } else {
+      return mat;
+    }
+  }
+}