I want to colorcode a numpy 2d-Array which contains values from 0-255 (grayscale). E.g. 0-150 colorcoded with rgb red (255,0,0) and 151-255 colorcoded blue (0,0,255).
After i did that the new Array with colorcoding shall be convertet to QImage (that is working) and convert that to QPixmap. The QPixmap then should be displayed with Pyqt.

My Problem, i cant convert the QImage to QPixmap after colorcoding. When i convert the 2d grayscale Array to Qimage to QPixmap it is working that way.
I also looked up if theres a way to use opencv or other libraries to colorcode my array, but didnt find anything.

import sys
import numpy as np
from PyQt5.QtWidgets import QApplication, QLabel, QVBoxLayout, QWidget
from PyQt5.QtGui import QImage, QPixmap


def apply_color_coding(ndarray):
    height, width = ndarray.shape
    color_image = np.zeros((height, width, 3), dtype=np.uint8)
    color_image[ndarray <= 100] = [0, 0, 255]  # Blau
    color_image[(ndarray > 100) & (ndarray <= 200)] = [0, 255, 0]  # Grün
    color_image[ndarray > 200] = [255, 0, 0]  # Rot
    return color_image


def array_to_pixmap(array):
    try:
        height, width, channels = array.shape
        bytes_per_line = channels * width
        print(f"Picturesize: {width}x{height}, Channels: {channels}, Bytes per line {bytes_per_line}")

        qimage = QImage(array.data, width, height, bytes_per_line, QImage.Format_RGB888).rgbSwapped()
        if qimage.isNull():
            print("Error: QImage is null")
            return None
        print("QImage done")

        pixmap = QPixmap.fromImage(qimage)
        if pixmap.isNull():
            print("Error: QPixmap is null")
            return None
        print("QPixmap done")

        return pixmap
    except Exception as e:
        print(f"Error converting: {e}")
        return None


class ImageDisplayWidget(QWidget):
    def __init__(self, pixmap, parent=None):
        super().__init__(parent)
        self.setWindowTitle("Farbkodiertes Bild")
        self.setGeometry(100, 100, pixmap.width(), pixmap.height())

        label = QLabel(self)
        label.setPixmap(pixmap)

        layout = QVBoxLayout()
        layout.addWidget(label)
        self.setLayout(layout)


def main():
    print("Start Main")

    # Beispiel-ndarray erstellen
    height, width = 300, 400
    ndarray = np.random.randint(0, 256, (height, width), dtype=np.uint8)

    print("colorcoding")
    color_coded_image = apply_color_coding(ndarray)

    print("Generate Pixmap")
    pixmap = array_to_pixmap(color_coded_image)

    if pixmap is None:
        print("Error pixmap")
        return

    app = QApplication(sys.argv)
    display_widget = ImageDisplayWidget(pixmap)
    display_widget.show()
    sys.exit(app.exec_())


if __name__ == "__main__":
    main()