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      1 # Copyright 2013 The Android Open Source Project
      2 #
      3 # Licensed under the Apache License, Version 2.0 (the "License");
      4 # you may not use this file except in compliance with the License.
      5 # You may obtain a copy of the License at
      6 #
      7 #      http://www.apache.org/licenses/LICENSE-2.0
      8 #
      9 # Unless required by applicable law or agreed to in writing, software
     10 # distributed under the License is distributed on an "AS IS" BASIS,
     11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     12 # See the License for the specific language governing permissions and
     13 # limitations under the License.
     14 
     15 import its.image
     16 import its.device
     17 import its.objects
     18 import pylab
     19 import os.path
     20 import matplotlib
     21 import matplotlib.pyplot
     22 import numpy
     23 
     24 def main():
     25     """Test that when the black level is locked, it doesn't change.
     26 
     27     Shoot with the camera covered (i.e.) dark/black. The test varies the
     28     sensitivity parameter and checks if the black level changes.
     29     """
     30     NAME = os.path.basename(__file__).split(".")[0]
     31 
     32     NUM_STEPS = 5
     33 
     34     req = {
     35         "android.blackLevel.lock": True,
     36         "android.control.mode": 0,
     37         "android.control.aeMode": 0,
     38         "android.control.awbMode": 0,
     39         "android.control.afMode": 0,
     40         "android.sensor.frameDuration": 0,
     41         "android.sensor.exposureTime": 10*1000*1000
     42         }
     43 
     44     # The most frequent pixel value in each image; assume this is the black
     45     # level, since the images are all dark (shot with the lens covered).
     46     modes = []
     47 
     48     with its.device.ItsSession() as cam:
     49         props = cam.get_camera_properties()
     50         sens_range = props['android.sensor.info.sensitivityRange']
     51         sensitivities = range(sens_range[0],
     52                               sens_range[1]+1,
     53                               int((sens_range[1] - sens_range[0]) / NUM_STEPS))
     54         for si, s in enumerate(sensitivities):
     55             req["android.sensor.sensitivity"] = s
     56             cap = cam.do_capture(req)
     57             yimg,_,_ = its.image.convert_capture_to_planes(cap)
     58             hist,_ = numpy.histogram(yimg*255, 256, (0,256))
     59             modes.append(numpy.argmax(hist))
     60 
     61             # Add this histogram to a plot; solid for shots without BL
     62             # lock, dashes for shots with BL lock
     63             pylab.plot(range(16), hist.tolist()[:16])
     64 
     65     pylab.xlabel("Luma DN, showing [0:16] out of full [0:256] range")
     66     pylab.ylabel("Pixel count")
     67     pylab.title("Histograms for different sensitivities")
     68     matplotlib.pyplot.savefig("%s_plot_histograms.png" % (NAME))
     69 
     70     # Check that the black levels are all the same.
     71     print "Black levels:", modes
     72     assert(all([modes[i] == modes[0] for i in range(len(modes))]))
     73 
     74 if __name__ == '__main__':
     75     main()
     76 
     77