UnisMindMap/mineru/utils/ocr_utils.py

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# Copyright (c) Opendatalab. All rights reserved.
import copy
import cv2
import numpy as np
class OcrConfidence:
min_confidence = 0.5
min_width = 3
LINE_WIDTH_TO_HEIGHT_RATIO_THRESHOLD = 4 # 一般情况下行宽度超过高度4倍时才是一个正常的横向文本块
def merge_spans_to_line(spans, threshold=0.6):
if len(spans) == 0:
return []
else:
# 按照y0坐标排序
spans.sort(key=lambda span: span['bbox'][1])
lines = []
current_line = [spans[0]]
for span in spans[1:]:
# 如果当前的span与当前行的最后一个span在y轴上重叠则添加到当前行
if _is_overlaps_y_exceeds_threshold(span['bbox'], current_line[-1]['bbox'], threshold):
current_line.append(span)
else:
# 否则,开始新行
lines.append(current_line)
current_line = [span]
# 添加最后一行
if current_line:
lines.append(current_line)
return lines
def _is_overlaps_y_exceeds_threshold(bbox1,
bbox2,
overlap_ratio_threshold=0.8):
"""检查两个bbox在y轴上是否有重叠并且该重叠区域的高度占两个bbox高度更低的那个超过80%"""
_, y0_1, _, y1_1 = bbox1
_, y0_2, _, y1_2 = bbox2
overlap = max(0, min(y1_1, y1_2) - max(y0_1, y0_2))
height1, height2 = y1_1 - y0_1, y1_2 - y0_2
# max_height = max(height1, height2)
min_height = min(height1, height2)
return (overlap / min_height) > overlap_ratio_threshold if min_height > 0 else False
def _is_overlaps_x_exceeds_threshold(bbox1,
bbox2,
overlap_ratio_threshold=0.8):
"""检查两个bbox在x轴上是否有重叠并且该重叠区域的宽度占两个bbox宽度更低的那个超过指定阈值"""
x0_1, _, x1_1, _ = bbox1
x0_2, _, x1_2, _ = bbox2
overlap = max(0, min(x1_1, x1_2) - max(x0_1, x0_2))
width1, width2 = x1_1 - x0_1, x1_2 - x0_2
min_width = min(width1, width2)
return (overlap / min_width) > overlap_ratio_threshold if min_width > 0 else False
def img_decode(content: bytes):
np_arr = np.frombuffer(content, dtype=np.uint8)
return cv2.imdecode(np_arr, cv2.IMREAD_UNCHANGED)
def check_img(img):
if isinstance(img, bytes):
img = img_decode(img)
if isinstance(img, np.ndarray) and len(img.shape) == 2:
img = cv2.cvtColor(img, cv2.COLOR_GRAY2BGR)
return img
def alpha_to_color(img, alpha_color=(255, 255, 255)):
if len(img.shape) == 3 and img.shape[2] == 4:
B, G, R, A = cv2.split(img)
alpha = A / 255
R = (alpha_color[0] * (1 - alpha) + R * alpha).astype(np.uint8)
G = (alpha_color[1] * (1 - alpha) + G * alpha).astype(np.uint8)
B = (alpha_color[2] * (1 - alpha) + B * alpha).astype(np.uint8)
img = cv2.merge((B, G, R))
return img
def preprocess_image(_image):
alpha_color = (255, 255, 255)
_image = alpha_to_color(_image, alpha_color)
return _image
def sorted_boxes(dt_boxes):
"""
Sort text boxes in order from top to bottom, left to right
args:
dt_boxes(array):detected text boxes with shape [4, 2]
return:
sorted boxes(array) with shape [4, 2]
"""
num_boxes = dt_boxes.shape[0]
sorted_boxes = sorted(dt_boxes, key=lambda x: (x[0][1], x[0][0]))
_boxes = list(sorted_boxes)
for i in range(num_boxes - 1):
for j in range(i, -1, -1):
if abs(_boxes[j + 1][0][1] - _boxes[j][0][1]) < 10 and \
(_boxes[j + 1][0][0] < _boxes[j][0][0]):
tmp = _boxes[j]
_boxes[j] = _boxes[j + 1]
_boxes[j + 1] = tmp
else:
break
return _boxes
def bbox_to_points(bbox):
""" 将bbox格式转换为四个顶点的数组 """
x0, y0, x1, y1 = bbox
return np.array([[x0, y0], [x1, y0], [x1, y1], [x0, y1]]).astype('float32')
def points_to_bbox(points):
""" 将四个顶点的数组转换为bbox格式 """
x0, y0 = points[0]
x1, _ = points[1]
_, y1 = points[2]
return [x0, y0, x1, y1]
def merge_intervals(intervals):
# Sort the intervals based on the start value
intervals.sort(key=lambda x: x[0])
merged = []
for interval in intervals:
# If the list of merged intervals is empty or if the current
# interval does not overlap with the previous, simply append it.
if not merged or merged[-1][1] < interval[0]:
merged.append(interval)
else:
# Otherwise, there is overlap, so we merge the current and previous intervals.
merged[-1][1] = max(merged[-1][1], interval[1])
return merged
def remove_intervals(original, masks):
# Merge all mask intervals
merged_masks = merge_intervals(masks)
result = []
original_start, original_end = original
for mask in merged_masks:
mask_start, mask_end = mask
# If the mask starts after the original range, ignore it
if mask_start > original_end:
continue
# If the mask ends before the original range starts, ignore it
if mask_end < original_start:
continue
# Remove the masked part from the original range
if original_start < mask_start:
result.append([original_start, mask_start - 1])
original_start = max(mask_end + 1, original_start)
# Add the remaining part of the original range, if any
if original_start <= original_end:
result.append([original_start, original_end])
return result
def update_det_boxes(dt_boxes, mfd_res):
new_dt_boxes = []
angle_boxes_list = []
for text_box in dt_boxes:
if calculate_is_angle(text_box):
angle_boxes_list.append(text_box)
continue
text_bbox = points_to_bbox(text_box)
masks_list = []
for mf_box in mfd_res:
mf_bbox = mf_box['bbox']
if _is_overlaps_y_exceeds_threshold(text_bbox, mf_bbox):
masks_list.append([mf_bbox[0], mf_bbox[2]])
text_x_range = [text_bbox[0], text_bbox[2]]
text_remove_mask_range = remove_intervals(text_x_range, masks_list)
temp_dt_box = []
for text_remove_mask in text_remove_mask_range:
temp_dt_box.append(bbox_to_points([text_remove_mask[0], text_bbox[1], text_remove_mask[1], text_bbox[3]]))
if len(temp_dt_box) > 0:
new_dt_boxes.extend(temp_dt_box)
new_dt_boxes.extend(angle_boxes_list)
return new_dt_boxes
def merge_overlapping_spans(spans):
"""
Merges overlapping spans on the same line.
:param spans: A list of span coordinates [(x1, y1, x2, y2), ...]
:return: A list of merged spans
"""
# Return an empty list if the input spans list is empty
if not spans:
return []
# Sort spans by their starting x-coordinate
spans.sort(key=lambda x: x[0])
# Initialize the list of merged spans
merged = []
for span in spans:
# Unpack span coordinates
x1, y1, x2, y2 = span
# If the merged list is empty or there's no horizontal overlap, add the span directly
if not merged or merged[-1][2] < x1:
merged.append(span)
else:
# If there is horizontal overlap, merge the current span with the previous one
last_span = merged.pop()
# Update the merged span's top-left corner to the smaller (x1, y1) and bottom-right to the larger (x2, y2)
x1 = min(last_span[0], x1)
y1 = min(last_span[1], y1)
x2 = max(last_span[2], x2)
y2 = max(last_span[3], y2)
# Add the merged span back to the list
merged.append((x1, y1, x2, y2))
# Return the list of merged spans
return merged
def merge_det_boxes(dt_boxes):
"""
Merge detection boxes.
This function takes a list of detected bounding boxes, each represented by four corner points.
The goal is to merge these bounding boxes into larger text regions.
Parameters:
dt_boxes (list): A list containing multiple text detection boxes, where each box is defined by four corner points.
Returns:
list: A list containing the merged text regions, where each region is represented by four corner points.
"""
# Convert the detection boxes into a dictionary format with bounding boxes and type
dt_boxes_dict_list = []
angle_boxes_list = []
for text_box in dt_boxes:
text_bbox = points_to_bbox(text_box)
if calculate_is_angle(text_box):
angle_boxes_list.append(text_box)
continue
text_box_dict = {'bbox': text_bbox}
dt_boxes_dict_list.append(text_box_dict)
# Merge adjacent text regions into lines
lines = merge_spans_to_line(dt_boxes_dict_list)
# Initialize a new list for storing the merged text regions
new_dt_boxes = []
for line in lines:
line_bbox_list = []
for span in line:
line_bbox_list.append(span['bbox'])
# 计算整行的宽度和高度
min_x = min(bbox[0] for bbox in line_bbox_list)
max_x = max(bbox[2] for bbox in line_bbox_list)
min_y = min(bbox[1] for bbox in line_bbox_list)
max_y = max(bbox[3] for bbox in line_bbox_list)
line_width = max_x - min_x
line_height = max_y - min_y
# 只有当行宽度超过高度4倍时才进行合并
if line_width > line_height * LINE_WIDTH_TO_HEIGHT_RATIO_THRESHOLD:
# Merge overlapping text regions within the same line
merged_spans = merge_overlapping_spans(line_bbox_list)
# Convert the merged text regions back to point format and add them to the new detection box list
for span in merged_spans:
new_dt_boxes.append(bbox_to_points(span))
else:
# 不进行合并,直接添加原始区域
for bbox in line_bbox_list:
new_dt_boxes.append(bbox_to_points(bbox))
new_dt_boxes.extend(angle_boxes_list)
return new_dt_boxes
def get_adjusted_mfdetrec_res(single_page_mfdetrec_res, useful_list):
paste_x, paste_y, xmin, ymin, xmax, ymax, new_width, new_height = useful_list
# Adjust the coordinates of the formula area
adjusted_mfdetrec_res = []
for mf_res in single_page_mfdetrec_res:
mf_xmin, mf_ymin, mf_xmax, mf_ymax = mf_res["bbox"]
# Adjust the coordinates of the formula area to the coordinates relative to the cropping area
x0 = mf_xmin - xmin + paste_x
y0 = mf_ymin - ymin + paste_y
x1 = mf_xmax - xmin + paste_x
y1 = mf_ymax - ymin + paste_y
# Filter formula blocks outside the graph
if any([x1 < 0, y1 < 0]) or any([x0 > new_width, y0 > new_height]):
continue
else:
adjusted_mfdetrec_res.append({
"bbox": [x0, y0, x1, y1],
})
return adjusted_mfdetrec_res
def get_ocr_result_list(ocr_res, useful_list, ocr_enable, bgr_image, lang):
paste_x, paste_y, xmin, ymin, xmax, ymax, new_width, new_height = useful_list
ocr_result_list = []
ori_im = bgr_image.copy()
for box_ocr_res in ocr_res:
if len(box_ocr_res) == 2:
p1, p2, p3, p4 = box_ocr_res[0]
text, score = box_ocr_res[1]
# logger.info(f"text: {text}, score: {score}")
if score < OcrConfidence.min_confidence: # 过滤低置信度的结果
continue
else:
p1, p2, p3, p4 = box_ocr_res
text, score = "", 1
if ocr_enable:
tmp_box = copy.deepcopy(np.array([p1, p2, p3, p4]).astype('float32'))
img_crop = get_rotate_crop_image(ori_im, tmp_box)
# average_angle_degrees = calculate_angle_degrees(box_ocr_res[0])
# if average_angle_degrees > 0.5:
poly = [p1, p2, p3, p4]
if (p3[0] - p1[0]) < OcrConfidence.min_width:
# logger.info(f"width too small: {p3[0] - p1[0]}, text: {text}")
continue
if calculate_is_angle(poly):
# logger.info(f"average_angle_degrees: {average_angle_degrees}, text: {text}")
# 与x轴的夹角超过0.5度,对边界做一下矫正
# 计算几何中心
x_center = sum(point[0] for point in poly) / 4
y_center = sum(point[1] for point in poly) / 4
new_height = ((p4[1] - p1[1]) + (p3[1] - p2[1])) / 2
new_width = p3[0] - p1[0]
p1 = [x_center - new_width / 2, y_center - new_height / 2]
p2 = [x_center + new_width / 2, y_center - new_height / 2]
p3 = [x_center + new_width / 2, y_center + new_height / 2]
p4 = [x_center - new_width / 2, y_center + new_height / 2]
# Convert the coordinates back to the original coordinate system
p1 = [p1[0] - paste_x + xmin, p1[1] - paste_y + ymin]
p2 = [p2[0] - paste_x + xmin, p2[1] - paste_y + ymin]
p3 = [p3[0] - paste_x + xmin, p3[1] - paste_y + ymin]
p4 = [p4[0] - paste_x + xmin, p4[1] - paste_y + ymin]
if ocr_enable:
ocr_result_list.append({
'category_id': 15,
'poly': p1 + p2 + p3 + p4,
'score': 1,
'text': text,
'np_img': img_crop,
'lang': lang,
})
else:
ocr_result_list.append({
'category_id': 15,
'poly': p1 + p2 + p3 + p4,
'score': float(round(score, 2)),
'text': text,
})
return ocr_result_list
def calculate_is_angle(poly):
p1, p2, p3, p4 = poly
height = ((p4[1] - p1[1]) + (p3[1] - p2[1])) / 2
if 0.8 * height <= (p3[1] - p1[1]) <= 1.2 * height:
return False
else:
# logger.info((p3[1] - p1[1])/height)
return True
def is_bbox_aligned_rect(points):
x_coords = points[:, 0]
y_coords = points[:, 1]
unique_x = np.unique(x_coords)
unique_y = np.unique(y_coords)
return len(unique_x) == 2 and len(unique_y) == 2
def get_rotate_crop_image(img, points):
'''
img_height, img_width = img.shape[0:2]
left = int(np.min(points[:, 0]))
right = int(np.max(points[:, 0]))
top = int(np.min(points[:, 1]))
bottom = int(np.max(points[:, 1]))
img_crop = img[top:bottom, left:right, :].copy()
points[:, 0] = points[:, 0] - left
points[:, 1] = points[:, 1] - top
'''
assert len(points) == 4, "shape of points must be 4*2"
if is_bbox_aligned_rect(points):
xmin = int(np.min(points[:, 0]))
xmax = int(np.max(points[:, 0]))
ymin = int(np.min(points[:, 1]))
ymax = int(np.max(points[:, 1]))
new_img = img[ymin:ymax, xmin:xmax].copy()
if new_img.shape[0] > 0 and new_img.shape[1] > 0:
return new_img
img_crop_width = int(
max(
np.linalg.norm(points[0] - points[1]),
np.linalg.norm(points[2] - points[3])))
img_crop_height = int(
max(
np.linalg.norm(points[0] - points[3]),
np.linalg.norm(points[1] - points[2])))
pts_std = np.float32([[0, 0], [img_crop_width, 0],
[img_crop_width, img_crop_height],
[0, img_crop_height]])
M = cv2.getPerspectiveTransform(points, pts_std)
dst_img = cv2.warpPerspective(
img,
M, (img_crop_width, img_crop_height),
borderMode=cv2.BORDER_REPLICATE,
flags=cv2.INTER_CUBIC)
dst_img_height, dst_img_width = dst_img.shape[0:2]
rotate_radio = 2
if dst_img_height * 1.0 / dst_img_width >= rotate_radio:
dst_img = np.rot90(dst_img)
return dst_img