How can I draw a degree symbol (º) Special Character on image using `cv2.putText` (Android +OpenCV)?

Question

I have to draw a text with a special character(100 degrees) over the image in Android by using the OpenCV library. Whenever I'll set text in putText function of OpenCV it's a show "100??". So please suggest if we have any third party lib or any other way to do this.

Answer 1

Because you're using Android, the backbone is inevitably Java. Try using Unicode\° inside your string, then write this to the image.

String degrees = "100\u00B0";
Imgproc.putText(img, degrees, ...);

Answer 2

I don't find any method in OpenCV to support degree symbol (º) Special Character. Please comment if anyone finds any method for the same. I have resolved the above issue by drawing a circle in place of degree symbol (º). Please find the code below:

private Bitmap setImageWithText(ImageView imageView) {

    Bitmap icon = BitmapFactory.decodeResource(getResources(), drawableID);

    Mat mat = new Mat();
    Bitmap bmp32 = icon.copy(Bitmap.Config.ARGB_8888, true);
    Utils.bitmapToMat(bmp32, mat);
 

    Point position = new Point(300, 300);
    Scalar color = new Scalar(255.0, 0.0, 0.0);
    int font = Imgproc.FONT_HERSHEY_SIMPLEX;
    int scale = 1;
    int thickness = 3;
    //Adding text to the image
    Imgproc.cvtColor(mat2, mat, 1, 4);

    Imgproc.putText(mat, "98.452", position, font, scale, color, thickness);
    int baseline[] = {0};
    Size textSize = Imgproc.getTextSize("98.452", Imgproc.FONT_HERSHEY_SIMPLEX, 1.0, 3, baseline);
    //Drawing a Circle
    Imgproc.circle(
            mat,                 //Matrix obj of the image
            new Point(300 + textSize.width+20, 300 -(textSize.height+20)),    //Center of the circle
            7,                    //Radius
            new Scalar(255.0, 0.0, 0.0),  //Scalar object for color
            3                      //Thickness of the circle
    );
    Imgproc.putText(mat, "F",  new Point(300 + (textSize.width+textSize.height), 300), font, scale, color, thickness);
    Bitmap output = Bitmap.createBitmap(bmp32.getWidth(), bmp32.getHeight(), bmp32.getConfig());
    Utils.matToBitmap(mat, output);
    return output;

}

Answer 3

import cv2

import numpy as np

im = cv2.imread("image1.jpg")

im = cv2.circle(im, (70,80), 5, (255,100,0), 1)

im = cv2.putText(im, "100", (5,100), cv2.FONT_HERSHEY_SIMPLEX, 1, (255,100,0), 1, cv2.LINE_AA)

cv2.imshow("pl", im)

cv2.waitKey(0)