51 def strip_soi_marker(jpeg):  argument
63   soi = jpeg[0:2]
66   return jpeg[2:]
69 def strip_appn_data(jpeg):  argument
85   while i < len(jpeg) - 1:
86     if [jpeg[i], jpeg[i + 1]] in _JPEG_APPN_MARKERS:
87       length = jpeg[i + 2] * 256 + jpeg[i + 3] + 2
89       jpeg = np.concatenate((jpeg[0:i], jpeg[length:]), axis=None)
90     elif ([jpeg[i], jpeg[i + 1]] == _JPEG_DQT_MARKER or
91           [jpeg[i], jpeg[i + 1]] == _JPEG_DHT_MARKER):
96   return jpeg
99 def find_dqt_markers(marker, jpeg):  argument
113   for i in range(len(jpeg) - marker_len + 1):
114     if list(jpeg[i:i + marker_len]) == marker:
119 def extract_dqts(jpeg, debug=False):  argument
138   dqt_markers = find_dqt_markers(_JPEG_DQT_MARKER, jpeg)
145                     jpeg[dqt:dqt + 2], jpeg[dqt + 2:dqt + 4])
146     dqt_size = jpeg[dqt + 2] * 256 + jpeg[dqt + 3] - 2  # strip off size marker
154       luma = np.array(jpeg[luma_start: luma_start + dqt_size])
155       chroma = np.array(jpeg[chroma_start: chroma_start + dqt_size])
168       matrix = np.array(jpeg[start:start + dqt_size])
169       if jpeg[dqt + 4]:  # chroma == 1
245         jpeg = cap['data']
248         jpeg = strip_soi_marker(jpeg)
251         jpeg = strip_appn_data(jpeg)
252         logging.debug('remaining JPEG header:%s', jpeg[0:4])
255         lumas_i, chromas_i = extract_dqts(jpeg, debug)