Ruben Brunk | 370e243 | 2014-10-14 18:33:23 -0700 | [diff] [blame^] | 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 | """Black level consistence test. |
| 26 | |
| 27 | Test: capture dark frames and check if black level correction is done |
| 28 | correctly. |
| 29 | 1. Black level should be roughly consistent for repeating shots. |
| 30 | 2. Noise distribution should be roughly centered at black level. |
| 31 | |
| 32 | Shoot with the camera covered (i.e.) dark/black. The test varies the |
| 33 | sensitivity parameter. |
| 34 | """ |
| 35 | NAME = os.path.basename(__file__).split(".")[0] |
| 36 | |
| 37 | NUM_REPEAT = 3 |
| 38 | NUM_STEPS = 3 |
| 39 | |
| 40 | # Only check the center part where LSC has little effects. |
| 41 | R = 200 |
| 42 | |
| 43 | # The most frequent pixel value in each image; assume this is the black |
| 44 | # level, since the images are all dark (shot with the lens covered). |
| 45 | ymodes = [] |
| 46 | umodes = [] |
| 47 | vmodes = [] |
| 48 | |
| 49 | with its.device.ItsSession() as cam: |
| 50 | props = cam.get_camera_properties() |
| 51 | sens_range = props['android.sensor.info.sensitivityRange'] |
| 52 | sens_step = (sens_range[1] - sens_range[0]) / float(NUM_STEPS-1) |
| 53 | sensitivities = [sens_range[0] + i*sens_step for i in range(NUM_STEPS)] |
| 54 | print "Sensitivities:", sensitivities |
| 55 | |
| 56 | for si, s in enumerate(sensitivities): |
| 57 | for rep in xrange(NUM_REPEAT): |
| 58 | req = its.objects.manual_capture_request(100, 1*1000*1000) |
| 59 | req["android.blackLevel.lock"] = True |
| 60 | req["android.sensor.sensitivity"] = s |
| 61 | cap = cam.do_capture(req) |
| 62 | yimg,uimg,vimg = its.image.convert_capture_to_planes(cap) |
| 63 | w = cap["width"] |
| 64 | h = cap["height"] |
| 65 | |
| 66 | # Magnify the noise in saved images to help visualize. |
| 67 | its.image.write_image(yimg * 2, |
| 68 | "%s_s=%05d_y.jpg" % (NAME, s), True) |
| 69 | its.image.write_image(numpy.absolute(uimg - 0.5) * 2, |
| 70 | "%s_s=%05d_u.jpg" % (NAME, s), True) |
| 71 | |
| 72 | yimg = yimg[w/2-R:w/2+R, h/2-R:h/2+R] |
| 73 | uimg = uimg[w/4-R/2:w/4+R/2, w/4-R/2:w/4+R/2] |
| 74 | vimg = vimg[w/4-R/2:w/4+R/2, w/4-R/2:w/4+R/2] |
| 75 | yhist,_ = numpy.histogram(yimg*255, 256, (0,256)) |
| 76 | ymodes.append(numpy.argmax(yhist)) |
| 77 | uhist,_ = numpy.histogram(uimg*255, 256, (0,256)) |
| 78 | umodes.append(numpy.argmax(uhist)) |
| 79 | vhist,_ = numpy.histogram(vimg*255, 256, (0,256)) |
| 80 | vmodes.append(numpy.argmax(vhist)) |
| 81 | |
| 82 | # Take 32 bins from Y, U, and V. |
| 83 | # Histograms of U and V are cropped at the center of 128. |
| 84 | pylab.plot(range(32), yhist.tolist()[0:32], 'rgb'[si]) |
| 85 | pylab.plot(range(32), uhist.tolist()[112:144], 'rgb'[si]+'--') |
| 86 | pylab.plot(range(32), vhist.tolist()[112:144], 'rgb'[si]+'--') |
| 87 | |
| 88 | pylab.xlabel("DN: Y[0:32], U[112:144], V[112:144]") |
| 89 | pylab.ylabel("Pixel count") |
| 90 | pylab.title("Histograms for different sensitivities") |
| 91 | matplotlib.pyplot.savefig("%s_plot_histograms.png" % (NAME)) |
| 92 | |
| 93 | print "Y black levels:", ymodes |
| 94 | print "U black levels:", umodes |
| 95 | print "V black levels:", vmodes |
| 96 | |
| 97 | if __name__ == '__main__': |
| 98 | main() |
| 99 | |