1 # Copyright 2014 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.device 16 import its.caps 17 import its.objects 18 import its.image 19 import os.path 20 from matplotlib import pylab 21 import matplotlib.pyplot 22 23 GR_PLANE = 1 # GR plane index in RGGB data 24 IMG_STATS_GRID = 9 # find used to find the center 11.11% 25 NAME = os.path.basename(__file__).split(".")[0] 26 NUM_STEPS = 5 27 VAR_THRESH = 1.01 # each shot must be 1% noisier than previous 28 29 30 def main(): 31 """Capture a set of raw images with increasing gains and measure the noise. 32 """ 33 34 with its.device.ItsSession() as cam: 35 36 props = cam.get_camera_properties() 37 its.caps.skip_unless(its.caps.raw16(props) and 38 its.caps.manual_sensor(props) and 39 its.caps.read_3a(props) and 40 its.caps.per_frame_control(props) and 41 not its.caps.mono_camera(props)) 42 debug = its.caps.debug_mode() 43 44 # Expose for the scene with min sensitivity 45 sens_min, _ = props["android.sensor.info.sensitivityRange"] 46 # Digital gains might not be visible on RAW data 47 sens_max = props["android.sensor.maxAnalogSensitivity"] 48 sens_step = (sens_max - sens_min) / NUM_STEPS 49 s_ae, e_ae, _, _, f_dist = cam.do_3a(get_results=True) 50 s_e_prod = s_ae * e_ae 51 52 variances = [] 53 for s in range(sens_min, sens_max, sens_step): 54 55 e = int(s_e_prod / float(s)) 56 req = its.objects.manual_capture_request(s, e, f_dist) 57 58 # Capture raw in debug mode, rawStats otherwise 59 # Measure the variance. Each shot should be noisier than the 60 # previous shot (as the gain is increasing). 61 if debug: 62 cap = cam.do_capture(req, cam.CAP_RAW) 63 gr = its.image.convert_capture_to_planes(cap, props)[1] 64 tile = its.image.get_image_patch(gr, 0.445, 0.445, 0.11, 0.11) 65 var = its.image.compute_image_variances(tile)[0] 66 img = its.image.convert_capture_to_rgb_image(cap, props=props) 67 its.image.write_image(img, "%s_s=%05d_var=%f.jpg" % 68 (NAME, s, var)) 69 else: 70 # Get the active array width and height. 71 aax = props["android.sensor.info.activeArraySize"]["left"] 72 aay = props["android.sensor.info.activeArraySize"]["top"] 73 aaw = props["android.sensor.info.activeArraySize"]["right"]-aax 74 aah = props["android.sensor.info.activeArraySize"]["bottom"]-aay 75 white_level = float(props["android.sensor.info.whiteLevel"]) 76 cap = cam.do_capture(req, 77 {"format": "rawStats", 78 "gridWidth": aaw/IMG_STATS_GRID, 79 "gridHeight": aah/IMG_STATS_GRID}) 80 _, var_image = its.image.unpack_rawstats_capture(cap) 81 cfa_idxs = its.image.get_canonical_cfa_order(props) 82 var = var_image[IMG_STATS_GRID/2, IMG_STATS_GRID/2, 83 cfa_idxs[GR_PLANE]]/white_level**2 84 85 variances.append(var) 86 print "s=%d, e=%d, var=%e" % (s, e, var) 87 88 x = range(len(variances)) 89 pylab.plot(x, variances, "-ro") 90 pylab.xticks(x) 91 pylab.xlabel("Setting Combination") 92 pylab.ylabel("Image Center Patch Variance") 93 matplotlib.pyplot.savefig("%s_variances.png" % NAME) 94 95 # Test that each shot is noisier than the previous one. 96 for i in range(len(variances) - 1): 97 assert variances[i] < variances[i+1] / VAR_THRESH 98 99 if __name__ == "__main__": 100 main() 101
