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# Copyright 2013 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import its.image
import its.device
import its.objects
import pylab
import os.path
import matplotlib
import matplotlib.pyplot
import numpy
def main():
"""Test that when the black level is locked, it doesn't change.
Shoot with the camera covered (i.e.) dark/black. The test varies the
sensitivity parameter and checks if the black level changes.
"""
NAME = os.path.basename(__file__).split(".")[0]
NUM_STEPS = 5
req = {
"android.blackLevel.lock": True,
"android.control.mode": 0,
"android.control.aeMode": 0,
"android.control.awbMode": 0,
"android.control.afMode": 0,
"android.sensor.frameDuration": 0,
"android.sensor.exposureTime": 10*1000*1000
}
# The most frequent pixel value in each image; assume this is the black
# level, since the images are all dark (shot with the lens covered).
modes = []
with its.device.ItsSession() as cam:
props = cam.get_camera_properties()
sens_range = props['android.sensor.info.sensitivityRange']
sensitivities = range(sens_range[0],
sens_range[1]+1,
int((sens_range[1] - sens_range[0]) / NUM_STEPS))
for si, s in enumerate(sensitivities):
req["android.sensor.sensitivity"] = s
cap = cam.do_capture(req)
yimg,_,_ = its.image.convert_capture_to_planes(cap)
hist,_ = numpy.histogram(yimg*255, 256, (0,256))
modes.append(numpy.argmax(hist))
# Add this histogram to a plot; solid for shots without BL
# lock, dashes for shots with BL lock
pylab.plot(range(16), hist.tolist()[:16])
pylab.xlabel("Luma DN, showing [0:16] out of full [0:256] range")
pylab.ylabel("Pixel count")
pylab.title("Histograms for different sensitivities")
matplotlib.pyplot.savefig("%s_plot_histograms.png" % (NAME))
# Check that the black levels are all the same.
print "Black levels:", modes
assert(all([modes[i] == modes[0] for i in range(len(modes))]))
if __name__ == '__main__':
main()
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