| # Copyright 2014 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.device |
| import its.caps |
| import its.objects |
| import its.image |
| import os.path |
| from matplotlib import pylab |
| import matplotlib |
| |
| GR_PLANE = 1 # GR plane index in RGGB data |
| IMG_STATS_GRID = 9 # find used to find the center 11.11% |
| NAME = os.path.basename(__file__).split(".")[0] |
| NUM_STEPS = 5 |
| VAR_THRESH = 1.01 # each shot must be 1% noisier than previous |
| |
| |
| def main(): |
| """Capture a set of raw images with increasing gains and measure the noise. |
| |
| Capture raw-only, in a burst. |
| """ |
| |
| with its.device.ItsSession() as cam: |
| |
| props = cam.get_camera_properties() |
| its.caps.skip_unless(its.caps.raw16(props) and |
| its.caps.manual_sensor(props) and |
| its.caps.read_3a(props) and |
| its.caps.per_frame_control(props) and |
| not its.caps.mono_camera(props)) |
| debug = its.caps.debug_mode() |
| |
| # Expose for the scene with min sensitivity |
| sens_min, _ = props["android.sensor.info.sensitivityRange"] |
| # Digital gains might not be visible on RAW data |
| sens_max = props["android.sensor.maxAnalogSensitivity"] |
| sens_step = (sens_max - sens_min) / NUM_STEPS |
| s_ae, e_ae, _, _, f_dist = cam.do_3a(get_results=True) |
| s_e_prod = s_ae * e_ae |
| |
| reqs = [] |
| settings = [] |
| for s in range(sens_min, sens_max, sens_step): |
| e = int(s_e_prod / float(s)) |
| req = its.objects.manual_capture_request(s, e, f_dist) |
| reqs.append(req) |
| settings.append((s, e)) |
| |
| if debug: |
| caps = cam.do_capture(reqs, cam.CAP_RAW) |
| else: |
| # Get the active array width and height. |
| aax = props["android.sensor.info.activeArraySize"]["left"] |
| aay = props["android.sensor.info.activeArraySize"]["top"] |
| aaw = props["android.sensor.info.activeArraySize"]["right"]-aax |
| aah = props["android.sensor.info.activeArraySize"]["bottom"]-aay |
| # Compute stats on a grid across each image. |
| caps = cam.do_capture(reqs, |
| {"format": "rawStats", |
| "gridWidth": aaw/IMG_STATS_GRID, |
| "gridHeight": aah/IMG_STATS_GRID}) |
| |
| variances = [] |
| for i, cap in enumerate(caps): |
| (s, e) = settings[i] |
| |
| # Each shot should be noisier than the previous shot (as the gain |
| # is increasing). Use the variance of the center stats grid cell. |
| if debug: |
| gr = its.image.convert_capture_to_planes(cap, props)[1] |
| tile = its.image.get_image_patch(gr, 0.445, 0.445, 0.11, 0.11) |
| var = its.image.compute_image_variances(tile)[0] |
| img = its.image.convert_capture_to_rgb_image(cap, props=props) |
| its.image.write_image(img, |
| "%s_s=%05d_var=%f.jpg" % (NAME, s, var)) |
| else: |
| # find white level |
| white_level = float(props["android.sensor.info.whiteLevel"]) |
| _, var_image = its.image.unpack_rawstats_capture(cap) |
| cfa_idxs = its.image.get_canonical_cfa_order(props) |
| var = var_image[IMG_STATS_GRID/2, IMG_STATS_GRID/2, |
| cfa_idxs[GR_PLANE]]/white_level**2 |
| variances.append(var) |
| print "s=%d, e=%d, var=%e" % (s, e, var) |
| |
| x = range(len(variances)) |
| pylab.plot(x, variances, "-ro") |
| pylab.xticks(x) |
| pylab.xlabel("Setting Combination") |
| pylab.ylabel("Image Center Patch Variance") |
| matplotlib.pyplot.savefig("%s_variances.png" % NAME) |
| |
| # Test that each shot is noisier than the previous one. |
| x.pop() # remove last element in x index |
| for i in x: |
| assert variances[i] < variances[i+1] / VAR_THRESH |
| |
| if __name__ == "__main__": |
| main() |
| |