pydicom_Tkinter.py 文件源码

def get_PGM_from_numpy_arr(arr, window_center, window_width,
                           lut_min=0, lut_max=255):
    '''real-valued numpy input  ->  PGM-image formatted byte string

    arr: real-valued numpy array to display as grayscale image
    window_center, window_width: to define max/min values to be mapped to the
                                 lookup-table range. WC/WW scaling is done
                                 according to DICOM-3 specifications.
    lut_min, lut_max: min/max values of (PGM-) grayscale table: do not change
    '''

    if np.isreal(arr).sum() != arr.size:
        raise ValueError

    # currently only support 8-bit colors
    if lut_max != 255:
        raise ValueError

    if arr.dtype != np.float64:
        arr = arr.astype(np.float64)

    # LUT-specific array scaling
    # width >= 1 (DICOM standard)
    window_width = max(1, window_width)

    wc, ww = np.float64(window_center), np.float64(window_width)
    lut_range = np.float64(lut_max) - lut_min

    minval = wc - 0.5 - (ww - 1.0) / 2.0
    maxval = wc - 0.5 + (ww - 1.0) / 2.0

    min_mask = (minval >= arr)
    to_scale = (arr > minval) & (arr < maxval)
    max_mask = (arr >= maxval)

    if min_mask.any():
        arr[min_mask] = lut_min
    if to_scale.any():
        arr[to_scale] = ((arr[to_scale] - (wc - 0.5)) /
                         (ww - 1.0) + 0.5) * lut_range + lut_min
    if max_mask.any():
        arr[max_mask] = lut_max

    # round to next integer values and convert to unsigned int
    arr = np.rint(arr).astype(np.uint8)

    # return PGM byte-data string
    return get_PGM_bytedata_string(arr)