ValueError: x_max小于或等于bbox的x_min

Question

我正在为一组图像和bboxes使用albumentations。

我的边界框是"yolo“格式，即(x_mid，y_mid，width，height)，全部归一化。

在为一组边界错误运行albumentations时，当边界框采用以下值时，上述错误就会出现(ValueError: x_max小于或等于bbox的x_min )：0.00017655367231635、0.0002155172413793、0.0003531073446327、0.0004310344827586。这里，x_min，y_min=0,0。

这个错误不会出现在其他边界框中-例如: 0.3060659468984962，0.4418239134174312，0.2412257095864662，0.5496854701834863。

当我稍微增加错误边界框的所有尺寸时，即:对于此错误BB 0.00017655367231635、0.0002155172413793、0.0003531073446327、0.0004310344827586，将x_mid、y_mid、x_width和y_width增加0.01时，此错误就解决了。

结果无误差BB: 0.01017655367231635，0.0102155172413793，0.0103531073446327，0.010431034482758601。

有没有人能告诉我一种不改变BB尺寸就能解决这个错误的方法？

我正在使用下面的代码来做albumentations：

import albumentations as A

    A.Compose(
    [
        A.LongestMaxSize(max_size=IMAGE_SIZE),
        A.PadIfNeeded(
            min_height=IMAGE_SIZE, min_width=IMAGE_SIZE, border_mode=cv2.BORDER_CONSTANT
        ),
        A.Normalize(mean=[0, 0, 0], std=[1, 1, 1], max_pixel_value=255,),
        ToTensorV2(),
    ],
    bbox_params=A.BboxParams(format="yolo", min_visibility=0.4, label_fields=[]),
)

详细错误：

---> 62                 augmentations_norm = self.transform_norm(image=image, bboxes=bboxes)
 63                 #print('Aug done')
 64                 image = augmentations_norm["image"]

/opt/conda/lib/python3.7/site-packages/albumentations/core/composition.py in __call__(self, force_apply, *args, **data)
    178             if dual_start_end is not None and idx == dual_start_end[0]:
    179                 for p in self.processors.values():
--> 180                     p.preprocess(data)
    181 
    182             data = t(force_apply=force_apply, **data)

/opt/conda/lib/python3.7/site-packages/albumentations/core/utils.py in preprocess(self, data)
     60         rows, cols = data["image"].shape[:2]
     61         for data_name in self.data_fields:
---> 62             data[data_name] = self.check_and_convert(data[data_name], rows, cols, direction="to")
     63 
     64     def check_and_convert(self, data, rows, cols, direction="to"):

/opt/conda/lib/python3.7/site-packages/albumentations/core/utils.py in check_and_convert(self, data, rows, cols, direction)
     68 
     69         if direction == "to":
---> 70             return self.convert_to_albumentations(data, rows, cols)
     71 
     72         return self.convert_from_albumentations(data, rows, cols)

/opt/conda/lib/python3.7/site-packages/albumentations/augmentations/bbox_utils.py in convert_to_albumentations(self, data, rows, cols)
     49 
     50     def convert_to_albumentations(self, data, rows, cols):
---> 51         return convert_bboxes_to_albumentations(data, self.params.format, rows, cols, check_validity=True)
     52 
     53 

/opt/conda/lib/python3.7/site-packages/albumentations/augmentations/bbox_utils.py in convert_bboxes_to_albumentations(bboxes, source_format, rows, cols, check_validity)
    300 def convert_bboxes_to_albumentations(bboxes, source_format, rows, cols, check_validity=False):
    301     """Convert a list bounding boxes from a format specified in `source_format` to the format used by albumentations"""
--> 302     return [convert_bbox_to_albumentations(bbox, source_format, rows, cols, check_validity) for bbox in bboxes]
    303 
    304 

/opt/conda/lib/python3.7/site-packages/albumentations/augmentations/bbox_utils.py in <listcomp>(.0)
    300 def convert_bboxes_to_albumentations(bboxes, source_format, rows, cols, check_validity=False):
    301     """Convert a list bounding boxes from a format specified in `source_format` to the format used by albumentations"""
--> 302     return [convert_bbox_to_albumentations(bbox, source_format, rows, cols, check_validity) for bbox in bboxes]
    303 
    304 

/opt/conda/lib/python3.7/site-packages/albumentations/augmentations/bbox_utils.py in convert_bbox_to_albumentations(bbox, source_format, rows, cols, check_validity)
    249     bbox = normalize_bbox(bbox, rows, cols)
    250     if check_validity:
--> 251         check_bbox(bbox)
    252     return bbox
    253 

/opt/conda/lib/python3.7/site-packages/albumentations/augmentations/bbox_utils.py in check_bbox(bbox)
    331     x_min, y_min, x_max, y_max = bbox[:4]
    332     if x_max <= x_min:
--> 333         raise ValueError("x_max is less than or equal to x_min for bbox {bbox}.".format(bbox=bbox))
    334     if y_max <= y_min:
    335         raise ValueError("y_max is less than or equal to y_min for bbox {bbox}.".format(bbox=bbox))

ValueError: x_max is less than or equal to x_min for bbox (0.00390625, 0.00390625, 0.00390625, 0.00390625, 0.0).

Answer 1

改编自评论：

在使用albumentations库中的边框时，在查看图像大小时，需要确保边框的宽度大于0。这在yolo边界框表示中可能不明显，但如果执行以下操作，则可以进行快速检查：

pix_w = int(bb[2]*img_w)
pix_h = int(bb[3]*img_w)
np.testing.assert_equal(np.all([pix_w>0,pix_h>0]), True)