opencv/samples/python/stitching_detailed.py

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

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

# Python 2/3 compatibility
from __future__ import print_function

import argparse
from collections import OrderedDict

import cv2 as cv
import numpy as np

EXPOS_COMP_CHOICES = OrderedDict()
EXPOS_COMP_CHOICES['gain_blocks'] = cv.detail.ExposureCompensator_GAIN_BLOCKS
EXPOS_COMP_CHOICES['gain'] = cv.detail.ExposureCompensator_GAIN
EXPOS_COMP_CHOICES['channel'] = cv.detail.ExposureCompensator_CHANNELS
EXPOS_COMP_CHOICES['channel_blocks'] = cv.detail.ExposureCompensator_CHANNELS_BLOCKS
EXPOS_COMP_CHOICES['no'] = cv.detail.ExposureCompensator_NO

BA_COST_CHOICES = OrderedDict()
BA_COST_CHOICES['ray'] = cv.detail_BundleAdjusterRay
BA_COST_CHOICES['reproj'] = cv.detail_BundleAdjusterReproj
BA_COST_CHOICES['affine'] = cv.detail_BundleAdjusterAffinePartial
BA_COST_CHOICES['no'] = cv.detail_NoBundleAdjuster

FEATURES_FIND_CHOICES = OrderedDict()
try:
    cv.xfeatures2d_SURF.create() # check if the function can be called
    FEATURES_FIND_CHOICES['surf'] = cv.xfeatures2d_SURF.create
except (AttributeError, cv.error) as e:
    print("SURF not available")
# if SURF not available, ORB is default
FEATURES_FIND_CHOICES['orb'] = cv.ORB.create
try:
    FEATURES_FIND_CHOICES['sift'] = cv.SIFT_create
except AttributeError:
    print("SIFT not available")
try:
    FEATURES_FIND_CHOICES['brisk'] = cv.BRISK_create
except AttributeError:
    print("BRISK not available")
try:
    FEATURES_FIND_CHOICES['akaze'] = cv.AKAZE_create
except AttributeError:
    print("AKAZE not available")

SEAM_FIND_CHOICES = OrderedDict()
SEAM_FIND_CHOICES['dp_color'] = cv.detail_DpSeamFinder('COLOR')
SEAM_FIND_CHOICES['dp_colorgrad'] = cv.detail_DpSeamFinder('COLOR_GRAD')
SEAM_FIND_CHOICES['voronoi'] = cv.detail.SeamFinder_createDefault(cv.detail.SeamFinder_VORONOI_SEAM)
SEAM_FIND_CHOICES['no'] = cv.detail.SeamFinder_createDefault(cv.detail.SeamFinder_NO)

ESTIMATOR_CHOICES = OrderedDict()
ESTIMATOR_CHOICES['homography'] = cv.detail_HomographyBasedEstimator
ESTIMATOR_CHOICES['affine'] = cv.detail_AffineBasedEstimator

WARP_CHOICES = (
    'spherical',
    'plane',
    'affine',
    'cylindrical',
    'fisheye',
    'stereographic',
    'compressedPlaneA2B1',
    'compressedPlaneA1.5B1',
    'compressedPlanePortraitA2B1',
    'compressedPlanePortraitA1.5B1',
    'paniniA2B1',
    'paniniA1.5B1',
    'paniniPortraitA2B1',
    'paniniPortraitA1.5B1',
    'mercator',
    'transverseMercator',
)

WAVE_CORRECT_CHOICES = OrderedDict()
WAVE_CORRECT_CHOICES['horiz'] = cv.detail.WAVE_CORRECT_HORIZ
WAVE_CORRECT_CHOICES['no'] = None
WAVE_CORRECT_CHOICES['vert'] = cv.detail.WAVE_CORRECT_VERT

BLEND_CHOICES = ('multiband', 'feather', 'no',)

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(
    '--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=list(FEATURES_FIND_CHOICES.keys())[0],
    help="Type of features used for images matching. The default is '%s'." % list(FEATURES_FIND_CHOICES.keys())[0],
    choices=FEATURES_FIND_CHOICES.keys(),
    type=str, dest='features'
)
parser.add_argument(
    '--matcher', action='store', default='homography',
    help="Matcher used for pairwise image matching. The default is 'homography'.",
    choices=('homography', 'affine'),
    type=str, dest='matcher'
)
parser.add_argument(
    '--estimator', action='store', default=list(ESTIMATOR_CHOICES.keys())[0],
    help="Type of estimator used for transformation estimation. The default is '%s'." % list(ESTIMATOR_CHOICES.keys())[0],
    choices=ESTIMATOR_CHOICES.keys(),
    type=str, dest='estimator'
)
parser.add_argument(
    '--match_conf', action='store',
    help="Confidence for feature matching step. The default is 0.3 for ORB and 0.65 for other feature types.",
    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=list(BA_COST_CHOICES.keys())[0],
    help="Bundle adjustment cost function. The default is '%s'." % list(BA_COST_CHOICES.keys())[0],
    choices=BA_COST_CHOICES.keys(),
    type=str, dest='ba'
)
parser.add_argument(
    '--ba_refine_mask', action='store', default='xxxxx',
    help="Set refinement mask for bundle adjustment. It looks like 'x_xxx', "
         "where 'x' means refine respective parameter and '_' means don't refine, "
         "and has the following format:<fx><skew><ppx><aspect><ppy>. "
         "The default mask is 'xxxxx'. "
         "If bundle adjustment doesn't support estimation of selected parameter then "
         "the respective flag is ignored.",
    type=str, dest='ba_refine_mask'
)
parser.add_argument(
    '--wave_correct', action='store', default=list(WAVE_CORRECT_CHOICES.keys())[0],
    help="Perform wave effect correction. The default is '%s'" % list(WAVE_CORRECT_CHOICES.keys())[0],
    choices=WAVE_CORRECT_CHOICES.keys(),
    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=WARP_CHOICES[0],
    help="Warp surface type. The default is '%s'." % WARP_CHOICES[0],
    choices=WARP_CHOICES,
    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=list(SEAM_FIND_CHOICES.keys())[0],
    help="Seam estimation method. The default is '%s'." % list(SEAM_FIND_CHOICES.keys())[0],
    choices=SEAM_FIND_CHOICES.keys(),
    type=str, dest='seam'
)
parser.add_argument(
    '--compose_megapix', action='store', default=-1,
    help="Resolution for compositing step. Use -1 for original resolution. The default is -1",
    type=float, dest='compose_megapix'
)
parser.add_argument(
    '--expos_comp', action='store', default=list(EXPOS_COMP_CHOICES.keys())[0],
    help="Exposure compensation method. The default is '%s'." % list(EXPOS_COMP_CHOICES.keys())[0],
    choices=EXPOS_COMP_CHOICES.keys(),
    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. The default is 32.",
    type=np.int32, dest='expos_comp_block_size'
)
parser.add_argument(
    '--blend', action='store', default=BLEND_CHOICES[0],
    help="Blending method. The default is '%s'." % BLEND_CHOICES[0],
    choices=BLEND_CHOICES,
    type=str, dest='blend'
)
parser.add_argument(
    '--blend_strength', action='store', default=5,
    help="Blending strength from [0,100] range. The default is 5",
    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 get_matcher(args):
    try_cuda = args.try_cuda
    matcher_type = args.matcher
    if args.match_conf is None:
        if args.features == 'orb':
            match_conf = 0.3
        else:
            match_conf = 0.65
    else:
        match_conf = args.match_conf
    range_width = args.rangewidth
    if matcher_type == "affine":
        matcher = cv.detail_AffineBestOf2NearestMatcher(False, try_cuda, match_conf)
    elif range_width == -1:
        matcher = cv.detail_BestOf2NearestMatcher(try_cuda, match_conf)
    else:
        matcher = cv.detail_BestOf2NearestRangeMatcher(range_width, try_cuda, match_conf)
    return matcher


def get_compensator(args):
    expos_comp_type = EXPOS_COMP_CHOICES[args.expos_comp]
    expos_comp_nr_feeds = args.expos_comp_nr_feeds
    expos_comp_block_size = args.expos_comp_block_size
    # expos_comp_nr_filtering = args.expos_comp_nr_filtering
    if expos_comp_type == cv.detail.ExposureCompensator_CHANNELS:
        compensator = cv.detail_ChannelsCompensator(expos_comp_nr_feeds)
        # compensator.setNrGainsFilteringIterations(expos_comp_nr_filtering)
    elif expos_comp_type == cv.detail.ExposureCompensator_CHANNELS_BLOCKS:
        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)
    return compensator


def main():
    args = parser.parse_args()
    img_names = args.img_names
    print(img_names)
    work_megapix = args.work_megapix
    seam_megapix = args.seam_megapix
    compose_megapix = args.compose_megapix
    conf_thresh = args.conf_thresh
    ba_refine_mask = args.ba_refine_mask
    wave_correct = WAVE_CORRECT_CHOICES[args.wave_correct]
    if args.save_graph is None:
        save_graph = False
    else:
        save_graph = True
    warp_type = args.warp
    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
    finder = FEATURES_FIND_CHOICES[args.features]()
    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:
            if seam_megapix > 0:
                seam_scale = min(1.0, np.sqrt(seam_megapix * 1e6 / (full_img.shape[0] * full_img.shape[1])))
            else:
                seam_scale = 1.0
            seam_work_aspect = seam_scale / work_scale
            is_seam_scale_set = True
        img_feat = cv.detail.computeImageFeatures2(finder, img)
        features.append(img_feat)
        img = cv.resize(src=full_img, dsize=None, fx=seam_scale, fy=seam_scale, interpolation=cv.INTER_LINEAR_EXACT)
        images.append(img)

    matcher = get_matcher(args)
    p = matcher.apply2(features)
    matcher.collectGarbage()

    if save_graph:
        with open(args.save_graph, 'w') as fh:
            fh.write(cv.detail.matchesGraphAsString(img_names, p, conf_thresh))

    indices = cv.detail.leaveBiggestComponent(features, p, conf_thresh)
    img_subset = []
    img_names_subset = []
    full_img_sizes_subset = []
    for i in range(len(indices)):
        img_names_subset.append(img_names[indices[i]])
        img_subset.append(images[indices[i]])
        full_img_sizes_subset.append(full_img_sizes[indices[i]])
    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()

    estimator = ESTIMATOR_CHOICES[args.estimator]()
    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)

    adjuster = BA_COST_CHOICES[args.ba]()
    adjuster.setConfThresh(conf_thresh)
    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)
    focals.sort()
    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 wave_correct is not None:
        rmats = []
        for cam in cameras:
            rmats.append(np.copy(cam.R))
        rmats = cv.detail.waveCorrect(rmats, wave_correct)
        for idx, cam in enumerate(cameras):
            cam.R = rmats[idx]
    corners = []
    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 could be 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)

    compensator = get_compensator(args)
    compensator.feed(corners=corners, images=images_warped, masks=masks_warped)

    seam_finder = SEAM_FIND_CHOICES[args.seam]
    masks_warped = seam_finder.find(images_warped_f, corners, masks_warped)
    compose_scale = 1
    corners = []
    sizes = []
    blender = None
    timelapser = None
    # https://github.com/opencv/opencv/blob/4.x/samples/cpp/stitching_detailed.cpp#L725 ?
    for idx, name in enumerate(img_names):
        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 = (int(round(full_img_sizes[i][0] * compose_scale)),
                      int(round(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)
        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 is 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.int32))
            elif blend_type == "feather":
                blender = cv.detail_FeatherBlender()
                blender.setSharpness(1. / blend_width)
            blender.prepare(dst_sz)
        elif timelapser is None and timelapse:
            timelapser = cv.detail.Timelapser_createDefault(timelapse_type)
            timelapser.initialize(corners, sizes)
        if timelapse:
            ma_tones = np.ones((image_warped_s.shape[0], image_warped_s.shape[1]), np.uint8)
            timelapser.process(image_warped_s, ma_tones, corners[idx])
            pos_s = img_names[idx].rfind("/")
            if pos_s == -1:
                fixed_file_name = "fixed_" + img_names[idx]
            else:
                fixed_file_name = img_names[idx][:pos_s + 1] + "fixed_" + img_names[idx][pos_s + 1:]
            cv.imwrite(fixed_file_name, 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)
        zoom_x = 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=zoom_x, fy=zoom_x)
        cv.imshow(result_name, dst)
        cv.waitKey()

    print("Done")


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