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 15import os.path 16import its.caps 17import its.device 18import its.image 19import its.objects 20import matplotlib 21from matplotlib import pylab 22 23GR_PLANE = 1 # GR plane index in RGGB data 24IMG_STATS_GRID = 9 # find used to find the center 11.11% 25NAME = os.path.basename(__file__).split(".")[0] 26NUM_STEPS = 5 27VAR_THRESH = 1.01 # each shot must be 1% noisier than previous 28 29 30def main(): 31 """Capture a set of raw images with increasing gains and measure the noise. 32 33 Capture raw-only, in a burst. 34 """ 35 36 with its.device.ItsSession() as cam: 37 38 props = cam.get_camera_properties() 39 its.caps.skip_unless(its.caps.raw16(props) and 40 its.caps.manual_sensor(props) and 41 its.caps.read_3a(props) and 42 its.caps.per_frame_control(props) and 43 not its.caps.mono_camera(props)) 44 debug = its.caps.debug_mode() 45 46 # Expose for the scene with min sensitivity 47 sens_min, _ = props["android.sensor.info.sensitivityRange"] 48 # Digital gains might not be visible on RAW data 49 sens_max = props["android.sensor.maxAnalogSensitivity"] 50 sens_step = (sens_max - sens_min) / NUM_STEPS 51 s_ae, e_ae, _, _, f_dist = cam.do_3a(get_results=True) 52 s_e_prod = s_ae * e_ae 53 54 reqs = [] 55 settings = [] 56 for s in range(sens_min, sens_max, sens_step): 57 e = int(s_e_prod / float(s)) 58 req = its.objects.manual_capture_request(s, e, f_dist) 59 reqs.append(req) 60 settings.append((s, e)) 61 62 if debug: 63 caps = cam.do_capture(reqs, cam.CAP_RAW) 64 else: 65 # Get the active array width and height. 66 aax = props["android.sensor.info.preCorrectionActiveArraySize"]["left"] 67 aay = props["android.sensor.info.preCorrectionActiveArraySize"]["top"] 68 aaw = props["android.sensor.info.preCorrectionActiveArraySize"]["right"]-aax 69 aah = props["android.sensor.info.preCorrectionActiveArraySize"]["bottom"]-aay 70 # Compute stats on a grid across each image. 71 caps = cam.do_capture(reqs, 72 {"format": "rawStats", 73 "gridWidth": aaw/IMG_STATS_GRID, 74 "gridHeight": aah/IMG_STATS_GRID}) 75 76 variances = [] 77 for i, cap in enumerate(caps): 78 (s, e) = settings[i] 79 80 # Each shot should be noisier than the previous shot (as the gain 81 # is increasing). Use the variance of the center stats grid cell. 82 if debug: 83 gr = its.image.convert_capture_to_planes(cap, props)[1] 84 tile = its.image.get_image_patch(gr, 0.445, 0.445, 0.11, 0.11) 85 var = its.image.compute_image_variances(tile)[0] 86 img = its.image.convert_capture_to_rgb_image(cap, props=props) 87 its.image.write_image(img, 88 "%s_s=%05d_var=%f.jpg" % (NAME, s, var)) 89 else: 90 # find white level 91 white_level = float(props["android.sensor.info.whiteLevel"]) 92 _, var_image = its.image.unpack_rawstats_capture(cap) 93 cfa_idxs = its.image.get_canonical_cfa_order(props) 94 var = var_image[IMG_STATS_GRID/2, IMG_STATS_GRID/2, 95 cfa_idxs[GR_PLANE]]/white_level**2 96 variances.append(var) 97 print "s=%d, e=%d, var=%e" % (s, e, var) 98 99 x = range(len(variances)) 100 pylab.plot(x, variances, "-ro") 101 pylab.xticks(x) 102 pylab.xlabel("Setting Combination") 103 pylab.ylabel("Image Center Patch Variance") 104 matplotlib.pyplot.savefig("%s_variances.png" % NAME) 105 106 # Test that each shot is noisier than the previous one. 107 x.pop() # remove last element in x index 108 for i in x: 109 msg = 'variances [i]: %.5f, [i+1]: %.5f, THRESH: %.2f' % ( 110 variances[i], variances[i+1], VAR_THRESH) 111 assert variances[i] < variances[i+1] / VAR_THRESH, msg 112 113if __name__ == "__main__": 114 main() 115 116