对COCO数据使用未压缩RLE对numpy数组进行编码

2024-05-14 23:44:06 发布

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要创建带注释图像的dataset.org/#download" rel="nofollow noreferrer">COCO数据集,需要根据对象类型将二进制掩码转换为多边形或未压缩的游程编码表示形式。在

pycocotools库具有对压缩RLE进行编码和解码的功能,但对多边形和未压缩的RLE没有任何功能。在

我可以使用skimage的度量库来generate polygons of masks,但我不确定如何创建未压缩的rle。在

我可以使用this RLE encoder从图像创建RLE的a表示,但我不确定COCO需要什么格式。COCO只是提到他们使用“自定义游程编码(RLE)方案”

例如

ground_truth_binary_mask = np.array([[  0,   0,   0,   0,   0,   0,   0,   0,   0,   0],
                                     [  0,   0,   0,   0,   0,   0,   0,   0,   0,   0],
                                     [  0,   0,   0,   0,   0,   1,   1,   1,   0,   0],
                                     [  0,   0,   0,   0,   0,   1,   1,   1,   0,   0],
                                     [  0,   0,   0,   0,   0,   1,   1,   1,   0,   0],
                                     [  0,   0,   0,   0,   0,   1,   1,   1,   0,   0],
                                     [  1,   0,   0,   0,   0,   0,   0,   0,   0,   0],
                                     [  0,   0,   0,   0,   0,   0,   0,   0,   0,   0],
                                     [  0,   0,   0,   0,   0,   0,   0,   0,   0,   0]], dtype=np.uint8)

fortran_ground_truth_binary_mask = np.asfortranarray(ground_truth_binary_mask)
rle(fortran_ground_truth_binary_mask)

输出:

^{pr2}$

这就是coco-RLE的样子:

{
    "segmentation": {
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            2,
            4,
            4,
            4,
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        ],
        "size": [
            240,
            320
        ]
    }
}

enter image description here


Tags: 图像功能编码npmask多边形datasetbinary
2条回答

有关格式的信息可在此处获得:https://github.com/cocodataset/cocoapi/blob/master/PythonAPI/pycocotools/mask.py

RLE is a simple yet efficient format for storing binary masks. RLE first divides a vector (or vectorized image) into a series of piecewise constant regions and then for each piece simply stores the length of that piece. For example, given M=[0 0 1 1 1 0 1] the RLE counts would be [2 3 1 1], or for M=[1 1 1 1 1 1 0] the counts would be [0 6 1] (note that the odd counts are always the numbers of zeros).

import numpy as np
from itertools import groupby

def binary_mask_to_rle(binary_mask):
    rle = {'counts': [], 'size': list(binary_mask.shape)}
    counts = rle.get('counts')
    for i, (value, elements) in enumerate(groupby(binary_mask.ravel(order='F'))):
        if i == 0 and value == 1:
            counts.append(0)
        counts.append(len(list(elements)))
    return rle

test_list_1 = np.array([0, 0, 1, 1, 1, 0, 1])
test_list_2 = np.array([1, 1, 1, 1, 1, 1, 0])

print(binary_mask_to_rle(test_list_1))
print(binary_mask_to_rle(test_list_2))

输出:

^{pr2}$

您可以使用mask.frPyObjects(rle, size_x, size_y)对RLE进行编码,然后执行所有常见的mask操作。在

import json
import numpy as np
from pycocotools import mask
from skimage import measure

ground_truth_binary_mask = np.array([[  0,   0,   0,   0,   0,   0,   0,   0,   0,   0],
                                     [  0,   0,   0,   0,   0,   0,   0,   0,   0,   0],
                                     [  0,   0,   0,   0,   0,   1,   1,   1,   0,   0],
                                     [  0,   0,   0,   0,   0,   1,   1,   1,   0,   0],
                                     [  0,   0,   0,   0,   0,   1,   1,   1,   0,   0],
                                     [  0,   0,   0,   0,   0,   1,   1,   1,   0,   0],
                                     [  1,   0,   0,   0,   0,   0,   0,   0,   0,   0],
                                     [  0,   0,   0,   0,   0,   0,   0,   0,   0,   0],
                                     [  0,   0,   0,   0,   0,   0,   0,   0,   0,   0]], dtype=np.uint8)

fortran_ground_truth_binary_mask = np.asfortranarray(ground_truth_binary_mask)

将掩码编码为RLE:

rle = binary_mask_to_rle(fortran_ground_truth_binary_mask)
print(rle)

输出:

{'counts': [6, 1, 40, 4, 5, 4, 5, 4, 21], 'size': [9, 10]}

压缩RLE,然后解码:

compressed_rle = mask.frPyObjects(rle, rle.get('size')[0], rle.get('size')[1])
mask.decode(compressed_rle)

输出:

array([[0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
       [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
       [0, 0, 0, 0, 0, 1, 1, 1, 0, 0],
       [0, 0, 0, 0, 0, 1, 1, 1, 0, 0],
       [0, 0, 0, 0, 0, 1, 1, 1, 0, 0],
       [0, 0, 0, 0, 0, 1, 1, 1, 0, 0],
       [1, 0, 0, 0, 0, 0, 0, 0, 0, 0],
       [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
       [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]], dtype=uint8)

为了解码在COCO注释中编码的二进制掩码,首先需要使用COCO's API来获得RLE,然后使用opencv来获得如下轮廓:

# Import libraries
import numpy as np
import cv2
import json
import mask

# Read the annotations
file_path = "coco/annotations/stuff_annotations_trainval2017/stuff_train2017.json"
with open(file_path, 'r') as f:
    data = json.load(f)

updated_data = []

# For each annotation
for annotation in data['annotations']:

    # Initialize variables
    obj = {}
    segmentation = []
    segmentation_polygons = []

    # Decode the binary mask
    mask_list = mask.decode(annotation['segmentation'])
    mask_list = np.ascontiguousarray(mask_list, dtype=np.uint8)
    mask_new, contours, hierarchy = cv2.findContours((mask_list).astype(np.uint8), cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)

    # Get the contours
    for contour in contours:
        contour = contour.flatten().tolist()
        segmentation.append(contour)
        if len(contour) > 4:
            segmentation.append(contour)
    if len(segmentation) == 0:
        continue

    # Get the polygons as (x, y) coordinates
    for i, segment in enumerate(segmentation):
        poligon = []
        poligons = []
        for j in range(len(segment)):
            poligon.append(segment[j])
            if (j+1)%2 == 0:
                poligons.append(poligon)
                poligon = []
        segmentation_polygons.append(poligons)

    # Save the segmentation and polygons for the current annotation
    obj['segmentation'] = segmentation
    obj['segmentation_polygons'] = segmentation_polygons
    updated_data.append(obj)

注意:只有COCO stuff 2017注释使用了二进制掩码,COCO person 2017注释没有使用,因此您不需要解码后者并找到它们的轮廓。

灵感来自this解决方案。在

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