Converting numpy image to QPixmap

Question

I am student of Computer-Sciences and I am learning image processing using OpenCv with Python. I am working on gender detection us

Answer 1

You must use the QImage::Format_Indexed8 format to convert the numpy array to QImage. I have implemented a method that converts some types of numpy arrays to QImage

def numpyQImage(image):
    qImg = QtGui.QImage()
    if image.dtype == np.uint8:
        if len(image.shape) == 2:
            channels = 1
            height, width = image.shape
            bytesPerLine = channels * width
            qImg = QtGui.QImage(
                image.data, width, height, bytesPerLine, QtGui.QImage.Format_Indexed8
            )
            qImg.setColorTable([QtGui.qRgb(i, i, i) for i in range(256)])
        elif len(image.shape) == 3:
            if image.shape[2] == 3:
                height, width, channels = image.shape
                bytesPerLine = channels * width
                qImg = QtGui.QImage(
                    image.data, width, height, bytesPerLine, QtGui.QImage.Format_RGB888
                )
            elif image.shape[2] == 4:
                height, width, channels = image.shape
                bytesPerLine = channels * width
                fmt = QtGui.QImage.Format_ARGB32
                qImg = QtGui.QImage(
                    image.data, width, height, bytesPerLine, QtGui.QImage.Format_ARGB32
                )
    return qImg

So in your case it should be:

def crop(self):
    if not self.work_IMAGE:
        return
    img = cv2.imread(self.work_IMAGE, cv2.IMREAD_GRAYSCALE)
    if img is None:
        return
    height, width = img.shape[:2]
    start_row, strt_col = int(height * 0.40), int(width * 0.15)
    end_row, end_col = int(height * 0.60), int(width * 0.90)
    croped = img[start_row:end_row, strt_col:end_col].copy()
    qImg = numpyQImage(croped)
    pixmap = QtGui.QPixmap.fromImage(qImg)
    pixmap = pixmap.scaled(self.roi_label.size(), QtCore.Qt.KeepAspectRatio)
    self.roi_label.setPixmap(pixmap)
    self.roi_label.setAlignment(QtCore.Qt.AlignCenter)