From dda878377bd2359dc7864b28a8fdc26f9f769a1d Mon Sep 17 00:00:00 2001 From: myhloli Date: Thu, 4 Jun 2026 02:05:03 +0800 Subject: [PATCH] feat: add character bounding box metrics and script role classification for improved text rendering --- mineru/utils/span_pre_proc.py | 129 ++++++++++++++++++++++++++++++++-- 1 file changed, 122 insertions(+), 7 deletions(-) diff --git a/mineru/utils/span_pre_proc.py b/mineru/utils/span_pre_proc.py index 7648d815..ec0f4288 100644 --- a/mineru/utils/span_pre_proc.py +++ b/mineru/utils/span_pre_proc.py @@ -280,6 +280,10 @@ LINE_STOP_FLAG = ('.', '!', '?', '。', '！', '？', ')', '）', '"', '”', ': LINE_START_FLAG = ('(', '（', '"', '“', '【', '{', '《', '<', '「', '『', '【', '[',) Span_Height_Ratio = 0.33 # 字符的中轴和span的中轴高度差不能超过1/3span高度 +SCRIPT_BODY_HEIGHT_RATIO = 0.9 +SCRIPT_CENTER_TOLERANCE_RATIO = 0.12 + + def calculate_char_in_span(char_bbox, span_bbox, char, span_height_ratio=Span_Height_Ratio): char_center_x = (char_bbox[0] + char_bbox[2]) / 2 char_center_y = (char_bbox[1] + char_bbox[3]) / 2 @@ -315,6 +319,114 @@ def calculate_char_in_span(char_bbox, span_bbox, char, span_height_ratio=Span_He return False +def _get_char_bbox_metrics(char): + """提取字符 bbox 的宽高和中心点，统一兼容 list 与 pdftext Bbox 对象。""" + bbox = char['bbox'] + x0, y0, x1, y1 = [float(v) for v in bbox] + return { + 'width': x1 - x0, + 'height': y1 - y0, + 'center_y': (y0 + y1) / 2, + } + + +def _get_char_bbox_metrics_list(chars): + """预计算 span 内全部字符的 bbox 指标，避免上下标判断重复解析 bbox。""" + return [_get_char_bbox_metrics(char) for char in chars] + + +def _is_valid_script_reference_char(char, metrics) -> bool: + """过滤空白和退化 bbox，只用真实可见字符估计正文主带。""" + if char['char'] in {' ', '\r', '\n'}: + return False + + return metrics['height'] > 1 and metrics['width'] > 0 + + +def _get_body_axis(chars, char_metrics): + """根据同一 span 内最大高度字符簇估计正文中心线和正文高度。""" + valid_metrics = [ + metrics for char, metrics in zip(chars, char_metrics) + if _is_valid_script_reference_char(char, metrics) + ] + if not valid_metrics: + return None + + max_height = max(metrics['height'] for metrics in valid_metrics) + body_metrics = [ + metrics for metrics in valid_metrics + if metrics['height'] >= max_height * SCRIPT_BODY_HEIGHT_RATIO + ] + if not body_metrics: + return None + + return { + 'center_y': statistics.median(metrics['center_y'] for metrics in body_metrics), + 'height': statistics.median(metrics['height'] for metrics in body_metrics), + } + + +def _classify_char_script_roles(chars, char_metrics): + """按正文主带判断每个字符属于正文、上标或下标。""" + body_axis = _get_body_axis(chars, char_metrics) + if body_axis is None or body_axis['height'] <= 0: + return ['body'] * len(chars) + + tolerance = body_axis['height'] * SCRIPT_CENTER_TOLERANCE_RATIO + roles = [] + for char, metrics in zip(chars, char_metrics): + if not _is_valid_script_reference_char(char, metrics): + roles.append('body') + continue + + char_center_y = metrics['center_y'] + if char_center_y < body_axis['center_y'] - tolerance: + roles.append('sup') + elif char_center_y > body_axis['center_y'] + tolerance: + roles.append('sub') + else: + roles.append('body') + return roles + + +def _append_script_wrapped_text(parts, role, text): + """把连续同类上下标文本包裹成 HTML 标签，正文保持原样。""" + if not text: + return + if role == 'sup': + parts.append(f'{text}') + elif role == 'sub': + parts.append(f'{text}') + else: + parts.append(text) + + +def _wrap_script_runs(role_text_parts): + """合并连续正文、上标、下标 run，避免每个字符单独生成标签。""" + wrapped_parts = [] + current_role = None + current_text_parts = [] + + for role, text in role_text_parts: + if role != current_role: + _append_script_wrapped_text( + wrapped_parts, + current_role, + ''.join(current_text_parts), + ) + current_role = role + current_text_parts = [text] + else: + current_text_parts.append(text) + + _append_script_wrapped_text( + wrapped_parts, + current_role, + ''.join(current_text_parts), + ) + return ''.join(wrapped_parts) + + def chars_to_content(span): # 检查span中的char是否为空 if len(span['chars']) != 0: @@ -326,28 +438,31 @@ def chars_to_content(span): ): chars = sorted(chars, key=lambda x: x['char_idx']) + char_metrics = _get_char_bbox_metrics_list(chars) # Calculate the width of each character - char_widths = [char['bbox'][2] - char['bbox'][0] for char in chars] + char_widths = [metrics['width'] for metrics in char_metrics] # Calculate the median width median_width = statistics.median(char_widths) + script_roles = _classify_char_script_roles(chars, char_metrics) - parts = [] + role_text_parts = [] for idx, char1 in enumerate(chars): char2 = chars[idx + 1] if idx + 1 < len(chars) else None + role1 = script_roles[idx] + role2 = script_roles[idx + 1] if char2 else None # 如果下一个char的x0和上一个char的x1距离超过0.25个字符宽度，则需要在中间插入一个空格 + role_text_parts.append((role1, char1['char'])) if ( char2 and char2['bbox'][0] - char1['bbox'][2] > median_width * 0.25 and char1['char'] != ' ' and char2['char'] != ' ' ): - parts.append(char1['char']) - parts.append(' ') - else: - parts.append(char1['char']) + space_role = role1 if role1 == role2 else 'body' + role_text_parts.append((space_role, ' ')) - content = ''.join(parts) + content = _wrap_script_runs(role_text_parts) content = __replace_unicode(content) content = __replace_ligatures(content) span['content'] = content.strip()