Issue 1:
System information (version)

OpenCV => ❔ 4.3 / 3.4

Operating System / Platform => ❔ Linux Ubuntu 16.04

Compiler => ❔ Android Studio (Gradle / Ninja / CMake / clang++)

Detailed description

I'm trying to use OpenCV on Android's NDK.

I have two similar environments - one integrated with OpenCV 4.3 and the other with OpenCV 3.4.

I created an Android C++ app.

For the 4.3 integration I followed this tutorial.

For the 3.4 integration I followed this tutorial.

I have a very basic native-lib.cpp file (see below), which is trying to use cv::imread.

In my code I provide the last trial - which includes the OpenCVLoader.initAsync instance, but I also tried the OpenCVLoader.initDebug way and System.loadLibrary("opencv_java4"), but the error remains.

I'm aware of the following issues:

#17282

#15536

#12074

#9512

#9437

and noticed the recent update regarding link issues (which I assumed was my problem):

#17282

I tried to build for my SDK version or against libc++, as described in the following:

https://stackoverflow.com/questions/51767214/android-studio-with-ndk-link-error-undefined-reference-to-stderr

https://stackoverflow.com/questions/52436506/undefined-references-error-opencv-android-with-ndk-18-c-static

https://stackoverflow.com/questions/52410712/ndk-problems-after-gnustl-has-been-removed-from-the-ndk-revision-r18/52436751#52436751

and noticed some other issues, which do not use exactly the same setup (for example, using ndk-build instead of cmake):

https://stackoverflow.com/questions/14649710/opencv-with-android-ndk-undefined-references

but failed to find anything new.

When trying to run the app I get the following errors:

undefined reference to `cv::imread'
clang++: error: linker command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.

Isn't undefined reference a linker issue?

Did I forget a compiler flag or something?

Steps to reproduce

Follow one of the tutorials (4.3 tutorial or 3.4 tutorial) to integrate OpenCV library into Android Studio.

Create the following simple native-lib.cpp:

#include <jni.h>
#include <string>
#include <opencv2/core.hpp>
#include <opencv2/imgcodecs.hpp>

extern "C" JNIEXPORT jstring JNICALL
Java_com_ocv_MainActivity_ocvLoadImage(
JNIEnv *env,
jobject thiz) {
using namespace cv;
using namespace std;
Mat image;
string imageName = "/Pictures/images/image-001.jpg";
image = imread(imageName, IMREAD_COLOR);
std::string returnString = "OpenCV load image: ";
if (! image.empty()){
returnString.append(imageName);
}
return env -> NewStringUTF(returnString.c_str());
}

and call it from this simple MainActivity.java:

package com.ocv;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
import android.util.Log;
import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.LoaderCallbackInterface;
import org.opencv.android.OpenCVLoader;
import org.opencv.core.Mat;

public class MainActivity extends AppCompatActivity {

static {
System.loadLibrary("native-lib");
System.loadLibrary("opencv_java4");
}

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}

private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
@Override
public void onManagerConnected(int status) {
if (status == LoaderCallbackInterface.SUCCESS) {
TextView textView = findViewById(R.id.sample_text);
String displayString =
textView.getText() +
"\n" + "OpenCV loaded successfully via initAsync" +
"\n" + ocvLoadImage();
textView.setText(displayString);
} else {
super.onManagerConnected(status);
}
}
};

@Override
public void onResume()
{
super.onResume();
OpenCVLoader.initAsync(
OpenCVLoader.OPENCV_VERSION_3_4_0,
this,
mLoaderCallback);
}
public native String ocvLoadImage(String imagePath);
}

NOTES:

When calling OpenCVLoader.initAsync, both the 4.3 and the 3.4 version use the OPENCV_VERSION_3_4_0 flag, since OPENCV_VERSION on 4.3 results in an error. I also tried the OpenCVLoader.initDebug and it produces the same error.

When commenting out the image = imread line in native-lib.cpp, the app runs OK, and returns the string (all cases).

the app's build.gradle:

externalNativeBuild {
cmake {
cppFlags "-frtti -fexceptions"
abiFilters 'arm64-v8a'
arguments "-DOpenCV_DIR=" + opencvsdk + "/sdk/native/jni"
}
}
...
packagingOptions {
pickFirst 'lib/arm64-v8a/libopencv_java4.so'
}

CMakeLists.txt:

cmake_minimum_required(VERSION 3.4.1)
include_directories(${OpenCV_DIR}/jni/include)
find_package(OpenCV 4.3
REQUIRED
java)
add_library(
native-lib
SHARED
native-lib.cpp )
find_library(
log-lib
log )
target_link_libraries( # Specifies the target library.
native-lib
${OpenCV_LIBRARIES}
${log-lib} )

Error

ERROR:

undefined reference to "cv::imread"

CLANG++:

/path/to/Sdk/ndk/21.1.6352462/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++ --target=aarch64-none-linux-android29 --gcc-toolchain=/path/to/Sdk/ndk/21.1.6352462/toolchains/llvm/prebuilt/linux-x86_64 --sysroot=/path/to/Sdk/ndk/21.1.6352462/toolchains/llvm/prebuilt/linux-x86_64/sysroot -fPIC -g -DANDROID -fdata-sections -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security -frtti -fexceptions -O0 -fno-limit-debug-info -Wl,--exclude-libs,libgcc.a -Wl,--exclude-libs,libgcc_real.a -Wl,--exclude-libs,libatomic.a -static-libstdc++ -Wl,--build-id -Wl,--fatal-warnings -Wl,--no-undefined -Qunused-arguments -shared -Wl,-soname,libnative-lib.so -o /path/to/app/build/intermediates/cmake/debug/obj/arm64-v8a/libnative-lib.so CMakeFiles/native-lib.dir/native-lib.cpp.o /path/to/opencv-4.3.0-android-sdk/OpenCV-android-sdk/sdk/native/libs/arm64-v8a/libopencv_java4.so /path/to/Sdk/ndk/21.1.6352462/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/aarch64-linux-android/29/liblog.so -ljnigraphics -llog -ldl -lz -latomic -lm

Issue 2:
System information (version)

OpenCV => 4.1.0.25

Operating System / Platform => Ubuntu 18.04.3 LTS

Compiler => python wheel

Detailed description

I'm trying to use the seam_finder of the stitching package (https://docs.opencv.org/master/d9/d24/group__stitching__seam.html).

This classes aims to find the optimal seams between two overlapping images. Regardless of the used seam finder, the inputs masks aren't updated.

Steps to reproduce

I've tried using a modified version of the detailed_stitching python scripts : https://github.com/opencv/opencv/blob/master/samples/python/stitching_detailed.py

Here my modified code which tests all the seam_finder and plot the masks using matplotlib :

I've also attached two images with which i've tried :

Here an example of non updated mask for the voronoi seam_finder :

"""
Stitching sample (advanced)
===========================

Show how to use Stitcher API from python.
"""

# Python 2/3 compatibility
from __future__ import print_function

import numpy as np
import copy
import cv2 as cv
import matplotlib.pyplot as plt

import sys
import argparse

parser = argparse.ArgumentParser(prog='stitching_detailed.py', description='Rotation model images stitcher')
parser.add_argument('img_names', nargs='+',help='files to stitch',type=str)
parser.add_argument('--preview',help='Run stitching in the preview mode. Works faster than usual mode but output image will have lower resolution.',type=bool,dest = 'preview' )
parser.add_argument('--try_cuda',action = 'store', default = False,help='Try to use CUDA. The default value is no. All default values are for CPU mode.',type=bool,dest = 'try_cuda' )
parser.add_argument('--work_megapix',action = 'store', default = 0.6,help=' Resolution for image registration step. The default is 0.6 Mpx',type=float,dest = 'work_megapix' )
parser.add_argument('--features',action = 'store', default = 'orb',help='Type of features used for images matching. The default is orb.',type=str,dest = 'features' )
parser.add_argument('--matcher',action = 'store', default = 'homography',help='Matcher used for pairwise image matching.',type=str,dest = 'matcher' )
parser.add_argument('--estimator',action = 'store', default = 'homography',help='Type of estimator used for transformation estimation.',type=str,dest = 'estimator' )
parser.add_argument('--match_conf',action = 'store', default = 0.3,help='Confidence for feature matching step. The default is 0.65 for surf and 0.3 for orb.',type=float,dest = 'match_conf' )
parser.add_argument('--conf_thresh',action = 'store', default = 1.0,help='Threshold for two images are from the same panorama confidence.The default is 1.0.',type=float,dest = 'conf_thresh' )
parser.add_argument('--ba',action = 'store', default = 'ray',help='Bundle adjustment cost function. The default is ray.',type=str,dest = 'ba' )
parser.add_argument('--ba_refine_mask',action = 'store', default = 'xxxxx',help='Set refinement mask for bundle adjustment. mask is "xxxxx"',type=str,dest = 'ba_refine_mask' )
parser.add_argument('--wave_correct',action = 'store', default = 'horiz',help='Perform wave effect correction. The default is "horiz"',type=str,dest = 'wave_correct' )
parser.add_argument('--save_graph',action = 'store', default = None,help='Save matches graph represented in DOT language to <file_name> file.',type=str,dest = 'save_graph' )
parser.add_argument('--warp',action = 'store', default = 'plane',help='Warp surface type. The default is "spherical".',type=str,dest = 'warp' )
parser.add_argument('--seam_megapix',action = 'store', default = 0.1,help=' Resolution for seam estimation step. The default is 0.1 Mpx.',type=float,dest = 'seam_megapix' )
parser.add_argument('--seam',action = 'store', default = 'no',help='Seam estimation method. The default is "gc_color".',type=str,dest = 'seam' )
parser.add_argument('--compose_megapix',action = 'store', default = -1,help='Resolution for compositing step. Use -1 for original resolution.',type=float,dest = 'compose_megapix' )
parser.add_argument('--expos_comp',action = 'store', default = 'no',help='Exposure compensation method. The default is "gain_blocks".',type=str,dest = 'expos_comp' )
parser.add_argument('--expos_comp_nr_feeds',action = 'store', default = 1,help='Number of exposure compensation feed.',type=np.int32,dest = 'expos_comp_nr_feeds' )
parser.add_argument('--expos_comp_nr_filtering',action = 'store', default = 2,help='Number of filtering iterations of the exposure compensation gains',type=float,dest = 'expos_comp_nr_filtering' )
parser.add_argument('--expos_comp_block_size',action = 'store', default = 32,help='BLock size in pixels used by the exposure compensator.',type=np.int32,dest = 'expos_comp_block_size' )
parser.add_argument('--blend',action = 'store', default = 'multiband',help='Blending method. The default is "multiband".',type=str,dest = 'blend' )
parser.add_argument('--blend_strength',action = 'store', default = 5,help='Blending strength from [0,100] range.',type=np.int32,dest = 'blend_strength' )
parser.add_argument('--output',action = 'store', default = 'result.jpg',help='The default is "result.jpg"',type=str,dest = 'output' )
parser.add_argument('--timelapse',action = 'store', default = None,help='Output warped images separately as frames of a time lapse movie, with "fixed_" prepended to input file names.',type=str,dest = 'timelapse' )
parser.add_argument('--rangewidth',action = 'store', default = -1,help='uses range_width to limit number of images to match with.',type=int,dest = 'rangewidth' )

__doc__ += '\n' + parser.format_help()

def main():
args = parser.parse_args()
img_names=args.img_names
print(img_names)
preview = args.preview
try_cuda = args.try_cuda
work_megapix = args.work_megapix
seam_megapix = args.seam_megapix
compose_megapix = args.compose_megapix
conf_thresh = args.conf_thresh
features_type = args.features
matcher_type = args.matcher
estimator_type = args.estimator
ba_cost_func = args.ba
ba_refine_mask = args.ba_refine_mask
wave_correct = args.wave_correct
if wave_correct=='no':
do_wave_correct= False
else:
do_wave_correct=True
if args.save_graph is None:
save_graph = False
else:
save_graph =True
save_graph_to = args.save_graph
warp_type = args.warp
if args.expos_comp=='no':
expos_comp_type = cv.detail.ExposureCompensator_NO
elif args.expos_comp=='gain':
expos_comp_type = cv.detail.ExposureCompensator_GAIN
elif args.expos_comp=='gain_blocks':
expos_comp_type = cv.detail.ExposureCompensator_GAIN_BLOCKS
elif args.expos_comp=='channel':
expos_comp_type = cv.detail.ExposureCompensator_CHANNELS
elif args.expos_comp=='channel_blocks':
expos_comp_type = cv.detail.ExposureCompensator_CHANNELS_BLOCKS
else:
print("Bad exposure compensation method")
exit()
expos_comp_nr_feeds = args.expos_comp_nr_feeds
expos_comp_nr_filtering = args.expos_comp_nr_filtering
expos_comp_block_size = args.expos_comp_block_size
match_conf = args.match_conf
seam_find_type = args.seam
blend_type = args.blend
blend_strength = args.blend_strength
result_name = args.output
if args.timelapse is not None:
timelapse = True
if args.timelapse=="as_is":
timelapse_type = cv.detail.Timelapser_AS_IS
elif args.timelapse=="crop":
timelapse_type = cv.detail.Timelapser_CROP
else:
print("Bad timelapse method")
exit()
else:
timelapse= False
range_width = args.rangewidth
if features_type=='orb':
finder= cv.ORB.create()
elif features_type=='surf':
finder= cv.xfeatures2d_SURF.create()
elif features_type=='sift':
finder= cv.xfeatures2d_SIFT.create()
else:
print ("Unknown descriptor type")
exit()
seam_work_aspect = 1
full_img_sizes=[]
features=[]
images=[]
is_work_scale_set = False
is_seam_scale_set = False
is_compose_scale_set = False;
for name in img_names:
full_img = cv.imread(cv.samples.findFile(name))
if full_img is None:
print("Cannot read image ", name)
exit()
full_img_sizes.append((full_img.shape[1],full_img.shape[0]))
if work_megapix < 0:
img = full_img
work_scale = 1
is_work_scale_set = True
else:
if is_work_scale_set is False:
work_scale = min(1.0, np.sqrt(work_megapix * 1e6 / (full_img.shape[0]*full_img.shape[1])))
is_work_scale_set = True
img = cv.resize(src=full_img, dsize=None, fx=work_scale, fy=work_scale, interpolation=cv.INTER_LINEAR_EXACT)
if is_seam_scale_set is False:
seam_scale = min(1.0, np.sqrt(seam_megapix * 1e6 / (full_img.shape[0]*full_img.shape[1])))
seam_work_aspect = seam_scale / work_scale
is_seam_scale_set = True
imgFea= cv.detail.computeImageFeatures2(finder,img)
features.append(imgFea)
img = cv.resize(src=full_img, dsize=None, fx=seam_scale, fy=seam_scale, interpolation=cv.INTER_LINEAR_EXACT)
images.append(img)
if matcher_type== "affine":
matcher = cv.detail_AffineBestOf2NearestMatcher(False, try_cuda, match_conf)
elif range_width==-1:
matcher = cv.detail.BestOf2NearestMatcher_create(try_cuda, match_conf)
else:
matcher = cv.detail.BestOf2NearestRangeMatcher_create(range_width, try_cuda, match_conf)
p=matcher.apply2(features)
matcher.collectGarbage()
if save_graph:
f = open(save_graph_to,"w")
f.write(cv.detail.matchesGraphAsString(img_names, p, conf_thresh))
f.close()
indices=cv.detail.leaveBiggestComponent(features,p,0.3)
img_subset =[]
img_names_subset=[]
full_img_sizes_subset=[]
num_images=len(indices)
for i in range(len(indices)):
img_names_subset.append(img_names[indices[i,0]])
img_subset.append(images[indices[i,0]])
full_img_sizes_subset.append(full_img_sizes[indices[i,0]])
images = img_subset;
img_names = img_names_subset;
full_img_sizes = full_img_sizes_subset;
num_images = len(img_names)
if num_images < 2:
print("Need more images")
exit()

if estimator_type == "affine":
estimator = cv.detail_AffineBasedEstimator()
else:
estimator = cv.detail_HomographyBasedEstimator()
b, cameras =estimator.apply(features,p,None)
if not b:
print("Homography estimation failed.")
exit()
for cam in cameras:
cam.R=cam.R.astype(np.float32)

if ba_cost_func == "reproj":
adjuster = cv.detail_BundleAdjusterReproj()
elif ba_cost_func == "ray":
adjuster = cv.detail_BundleAdjusterRay()
elif ba_cost_func == "affine":
adjuster = cv.detail_BundleAdjusterAffinePartial()
elif ba_cost_func == "no":
adjuster = cv.detail_NoBundleAdjuster()
else:
print( "Unknown bundle adjustment cost function: ", ba_cost_func )
exit()
adjuster.setConfThresh(1)
refine_mask=np.zeros((3,3),np.uint8)
if ba_refine_mask[0] == 'x':
refine_mask[0,0] = 1
if ba_refine_mask[1] == 'x':
refine_mask[0,1] = 1
if ba_refine_mask[2] == 'x':
refine_mask[0,2] = 1
if ba_refine_mask[3] == 'x':
refine_mask[1,1] = 1
if ba_refine_mask[4] == 'x':
refine_mask[1,2] = 1
adjuster.setRefinementMask(refine_mask)
b,cameras = adjuster.apply(features,p,cameras)
if not b:
print("Camera parameters adjusting failed.")
exit()
focals=[]
for cam in cameras:
focals.append(cam.focal)
sorted(focals)
if len(focals)%2==1:
warped_image_scale = focals[len(focals) // 2]
else:
warped_image_scale = (focals[len(focals) // 2]+focals[len(focals) // 2-1])/2
if do_wave_correct:
rmats=[]
for cam in cameras:
rmats.append(np.copy(cam.R))
rmats	=	cv.detail.waveCorrect(	rmats, cv.detail.WAVE_CORRECT_HORIZ)
for idx,cam in enumerate(cameras):
cam.R = rmats[idx]
corners=[]
mask=[]
masks_warped=[]
images_warped=[]
sizes=[]
masks=[]
for i in range(0,num_images):
um=cv.UMat(255*np.ones((images[i].shape[0],images[i].shape[1]),np.uint8))
masks.append(um)

warper = cv.PyRotationWarper(warp_type,warped_image_scale*seam_work_aspect) # warper peut etre nullptr?
for idx in range(0,num_images):
K = cameras[idx].K().astype(np.float32)
swa = seam_work_aspect
K[0,0] *= swa
K[0,2] *= swa
K[1,1] *= swa
K[1,2] *= swa
corner,image_wp =warper.warp(images[idx],K,cameras[idx].R,cv.INTER_LINEAR, cv.BORDER_REFLECT)
corners.append(corner)
sizes.append((image_wp.shape[1],image_wp.shape[0]))
images_warped.append(image_wp)

p,mask_wp =warper.warp(masks[idx],K,cameras[idx].R,cv.INTER_NEAREST, cv.BORDER_CONSTANT)
masks_warped.append(mask_wp.get())
images_warped_f=[]
for img in images_warped:
imgf=img.astype(np.float32)
images_warped_f.append(imgf)
if cv.detail.ExposureCompensator_CHANNELS == expos_comp_type:
compensator = cv.detail_ChannelsCompensator(expos_comp_nr_feeds)
# compensator.setNrGainsFilteringIterations(expos_comp_nr_filtering)
elif cv.detail.ExposureCompensator_CHANNELS_BLOCKS == expos_comp_type:
compensator=cv.detail_BlocksChannelsCompensator(expos_comp_block_size, expos_comp_block_size,expos_comp_nr_feeds)
# compensator.setNrGainsFilteringIterations(expos_comp_nr_filtering)
else:
compensator=cv.detail.ExposureCompensator_createDefault(expos_comp_type)
compensator.feed(corners=corners, images=images_warped, masks=masks_warped)
for finder_id, finder_name in enumerate(
["no", "voronoi", "gc_color", "gc_colorgrad", "dp_color", "dp_colorgrad"]
):
if seam_find_type == "no":
seam_finder = cv.detail.SeamFinder_createDefault(cv.detail.SeamFinder_NO)
elif seam_find_type == "voronoi":
seam_finder = cv.detail.SeamFinder_createDefault(cv.detail.SeamFinder_VORONOI_SEAM);
elif seam_find_type == "gc_color":
seam_finder = cv.detail_GraphCutSeamFinder("COST_COLOR")
elif seam_find_type == "gc_colorgrad":
seam_finder = cv.detail_GraphCutSeamFinder("COST_COLOR_GRAD")
elif seam_find_type == "dp_color":
seam_finder = cv.detail_DpSeamFinder("COLOR")
elif seam_find_type == "dp_colorgrad":
seam_finder = cv.detail_DpSeamFinder("COLOR_GRAD")
if seam_finder is None:
print("Can't create the following seam finder ",seam_find_type)
exit()

masks_warped_updated = copy.deepcopy(masks_warped)
seam_finder.find(images_warped_f, corners, masks_warped_updated)
for figure_n in range(len(masks_warped)):
plt.figure(figure_n)
ax = plt.subplot(6, 3, finder_id*3+1)
plt.imshow(images_warped[figure_n])
plt.title("image")
plt.subplot(6, 3, finder_id*3+2, sharex=ax, sharey=ax)
plt.imshow(masks_warped[figure_n])
plt.title("original mask")
plt.subplot(6, 3, finder_id*3+3, sharex=ax, sharey=ax)
plt.title("updated mask")
plt.imshow(masks_warped_updated[figure_n])

plt.show()
imgListe=[]
compose_scale=1
corners=[]
sizes=[]
images_warped=[]
images_warped_f=[]
masks=[]
blender= None
timelapser=None
compose_work_aspect=1
for idx,name in enumerate(img_names): # https://github.com/opencv/opencv/blob/master/samples/cpp/stitching_detailed.cpp#L725 ?
full_img = cv.imread(name)
if not is_compose_scale_set:
if compose_megapix > 0:
compose_scale = min(1.0, np.sqrt(compose_megapix * 1e6 / (full_img.shape[0]*full_img.shape[1])))
is_compose_scale_set = True;
compose_work_aspect = compose_scale / work_scale;
warped_image_scale *= compose_work_aspect
warper = cv.PyRotationWarper(warp_type,warped_image_scale)
for i in range(0,len(img_names)):
cameras[i].focal *= compose_work_aspect
cameras[i].ppx *= compose_work_aspect
cameras[i].ppy *= compose_work_aspect
sz = (full_img_sizes[i][0] * compose_scale,full_img_sizes[i][1]* compose_scale)
K = cameras[i].K().astype(np.float32)
roi = warper.warpRoi(sz, K, cameras[i].R);
corners.append(roi[0:2])
sizes.append(roi[2:4])
if abs(compose_scale - 1) > 1e-1:
img =cv.resize(src=full_img, dsize=None, fx=compose_scale, fy=compose_scale, interpolation=cv.INTER_LINEAR_EXACT)
else:
img = full_img;
img_size = (img.shape[1],img.shape[0]);
K=cameras[idx].K().astype(np.float32)
corner,image_warped =warper.warp(img,K,cameras[idx].R,cv.INTER_LINEAR, cv.BORDER_REFLECT)
mask =255*np.ones((img.shape[0],img.shape[1]),np.uint8)
p,mask_warped =warper.warp(mask,K,cameras[idx].R,cv.INTER_NEAREST, cv.BORDER_CONSTANT)
compensator.apply(idx,corners[idx],image_warped,mask_warped)
image_warped_s = image_warped.astype(np.int16)
image_warped=[]
dilated_mask = cv.dilate(masks_warped[idx],None)
seam_mask = cv.resize(dilated_mask,(mask_warped.shape[1],mask_warped.shape[0]),0,0,cv.INTER_LINEAR_EXACT)
mask_warped = cv.bitwise_and(seam_mask,mask_warped)
if blender==None and not timelapse:
blender = cv.detail.Blender_createDefault(cv.detail.Blender_NO)
dst_sz = cv.detail.resultRoi(corners=corners,sizes=sizes)
blend_width = np.sqrt(dst_sz[2]*dst_sz[3]) * blend_strength / 100
if blend_width < 1:
blender = cv.detail.Blender_createDefault(cv.detail.Blender_NO)
elif blend_type == "multiband":
blender = cv.detail_MultiBandBlender()
blender.setNumBands((np.log(blend_width)/np.log(2.) - 1.).astype(np.int))
elif blend_type == "feather":
blender = cv.detail_FeatherBlender()
blender.setSharpness(1./blend_width)
blender.prepare(dst_sz)
elif timelapser==None and timelapse:
timelapser = cv.detail.Timelapser_createDefault(timelapse_type)
timelapser.initialize(corners, sizes)
if timelapse:
matones=np.ones((image_warped_s.shape[0],image_warped_s.shape[1]), np.uint8)
timelapser.process(image_warped_s, matones, corners[idx])
pos_s = img_names[idx].rfind("/");
if pos_s == -1:
fixedFileName = "fixed_" + img_names[idx];
else:
fixedFileName = img_names[idx][:pos_s + 1 ]+"fixed_" + img_names[idx][pos_s + 1: ]
cv.imwrite(fixedFileName, timelapser.getDst())
else:
blender.feed(cv.UMat(image_warped_s), mask_warped, corners[idx])
if not timelapse:
result=None
result_mask=None
result,result_mask = blender.blend(result,result_mask)
cv.imwrite(result_name,result)
zoomx = 600.0 / result.shape[1]
dst=cv.normalize(src=result,dst=None,alpha=255.,norm_type=cv.NORM_MINMAX,dtype=cv.CV_8U)
dst=cv.resize(dst,dsize=None,fx=zoomx,fy=zoomx)
cv.imshow(result_name,dst)
cv.waitKey()

print('Done')

if __name__ == '__main__':
print(__doc__)
main()
cv.destroyAllWindows()