Suya OCR API — vLLM-backed, OpenAI-compatible OCR service

FastAPI service wrapping the Surya-OCR-2 model (datalab-to) served through vLLM:
legacy /v1/api/ai/* endpoints, an OpenAI-compatible /v1/chat/completions endpoint,
a coalescing request batcher, a local OCR CLI, Docker packaging, multilingual
example outputs, and quantization/concurrency benchmarks.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Fu Dai
2026-06-17 10:20:02 +04:00
co-authored by Claude Opus 4.8
commit 1a585693be
147 changed files with 13827 additions and 0 deletions
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"""Pixel-content heuristics for detecting blank or near-uniform image regions.
Used by both the layout predictor (drop hallucinated layout blocks over empty
space) and the recognition predictor (drop hallucinated text blocks from
full-page OCR, decide whether an empty full-page output is a correct blank-page
read or a failure).
Two signals, combined:
* near-white fraction — most pixels have every RGB channel above a threshold
* pixel-value standard deviation — the region is essentially one color
(catches uniform-color fills that the white check misses)
"""
from __future__ import annotations
import numpy as np
from PIL import Image
# Per-channel value at/above which a pixel is considered "near-white".
# Tolerates the small noise typical of PDF renders at 96 DPI.
BLANK_WHITE_THRESHOLD = 245
# Fraction of pixels that must be near-white for a region to count as blank.
BLANK_PIXEL_FRACTION = 0.99
# Pixel-value std below which a region is "essentially one color" regardless
# of what that color is (catches solid-fill rectangles, dark banners, etc.).
UNIFORM_COLOR_STD = 8.0
def near_white_fraction(
image: Image.Image, white_threshold: int = BLANK_WHITE_THRESHOLD
) -> float:
"""Fraction of pixels where every RGB channel ≥ ``white_threshold``."""
arr = np.asarray(image.convert("RGB"))
if arr.size == 0:
return 0.0
return float(np.all(arr >= white_threshold, axis=-1).mean())
def is_blank_region(
image: Image.Image,
*,
white_threshold: int = BLANK_WHITE_THRESHOLD,
blank_pixel_fraction: float = BLANK_PIXEL_FRACTION,
uniform_color_std: float = UNIFORM_COLOR_STD,
) -> bool:
"""True iff the image is essentially blank — either mostly near-white or
near-uniform color. Use this on a per-block crop or a whole page.
Returns False for empty (0-pixel) crops so callers don't accidentally
treat a degenerate bbox as blank.
"""
arr = np.asarray(image.convert("RGB"))
if arr.size == 0:
return False
if np.all(arr >= white_threshold, axis=-1).mean() > blank_pixel_fraction:
return True
# Per-channel std — a uniform solid color (e.g., red banner with RGB=(200,50,50))
# has each channel constant across pixels, but mixing channels inflates the
# aggregate std. Check each channel independently.
per_channel_std = arr.reshape(-1, arr.shape[-1]).std(axis=0)
if float(per_channel_std.max()) < uniform_color_std:
return True
return False
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from typing import Optional, Any
import torch
from surya.settings import settings
class ModelLoader:
def __init__(self, checkpoint: Optional[str] = None):
self.checkpoint = checkpoint
def model(
self,
device: torch.device | str | None = settings.TORCH_DEVICE_MODEL,
dtype: Optional[torch.dtype | str] = settings.MODEL_DTYPE,
attention_implementation: Optional[str] = None,
) -> Any:
raise NotImplementedError()
def processor(
self,
device: torch.device | str | None = settings.TORCH_DEVICE_MODEL,
dtype: Optional[torch.dtype | str] = settings.MODEL_DTYPE,
) -> Any:
raise NotImplementedError()
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import copy
from typing import List, Optional
import numpy as np
from pydantic import BaseModel, field_validator, computed_field
import numbers
class PolygonBox(BaseModel):
polygon: List[List[float]]
confidence: Optional[float] = None
@field_validator("polygon", mode="before")
@classmethod
def convert_bbox_to_polygon(cls, value):
if isinstance(value, (list, tuple)) and len(value) == 4:
if all(isinstance(x, numbers.Number) for x in value):
value = [float(v) for v in value]
x_min, y_min, x_max, y_max = value
polygon = [
[x_min, y_min],
[x_max, y_min],
[x_max, y_max],
[x_min, y_max],
]
return polygon
elif all(
isinstance(point, (list, tuple)) and len(point) == 2 for point in value
):
value = [[float(v) for v in point] for point in value]
return value
elif isinstance(value, np.ndarray):
if value.shape == (4, 2):
return value.tolist()
raise ValueError(
f"Input must be either a bbox [x_min, y_min, x_max, y_max] or a polygon with 4 corners [(x,y), (x,y), (x,y), (x,y)]. All values must be numeric. You passed {value} of type {type(value)}. The first value is of type {type(value[0])}."
)
@property
def height(self):
return self.bbox[3] - self.bbox[1]
@property
def width(self):
return self.bbox[2] - self.bbox[0]
@property
def area(self):
return self.width * self.height
@computed_field
@property
def bbox(self) -> List[float]:
x_coords = [point[0] for point in self.polygon]
y_coords = [point[1] for point in self.polygon]
return [min(x_coords), min(y_coords), max(x_coords), max(y_coords)]
def rescale(self, processor_size, image_size):
# Point is in x, y format
page_width, page_height = processor_size
img_width, img_height = image_size
width_scaler = img_width / page_width
height_scaler = img_height / page_height
for corner in self.polygon:
corner[0] = int(corner[0] * width_scaler)
corner[1] = int(corner[1] * height_scaler)
def round(self, divisor):
for corner in self.polygon:
corner[0] = int(corner[0] / divisor) * divisor
corner[1] = int(corner[1] / divisor) * divisor
def fit_to_bounds(self, bounds):
new_corners = copy.deepcopy(self.polygon)
for corner in new_corners:
corner[0] = max(min(corner[0], bounds[2]), bounds[0])
corner[1] = max(min(corner[1], bounds[3]), bounds[1])
self.polygon = new_corners
def expand(self, x_margin: float, y_margin: float):
new_polygon = []
x_margin = x_margin * self.width
y_margin = y_margin * self.height
for idx, poly in enumerate(self.polygon):
if idx == 0:
new_polygon.append([int(poly[0] - x_margin), int(poly[1] - y_margin)])
elif idx == 1:
new_polygon.append([int(poly[0] + x_margin), int(poly[1] - y_margin)])
elif idx == 2:
new_polygon.append([int(poly[0] + x_margin), int(poly[1] + y_margin)])
elif idx == 3:
new_polygon.append([int(poly[0] - x_margin), int(poly[1] + y_margin)])
self.polygon = new_polygon
def intersection_area(self, other, x_margin=0, y_margin=0):
x_overlap = self.x_overlap(other, x_margin)
y_overlap = self.y_overlap(other, y_margin)
return x_overlap * y_overlap
def x_overlap(self, other, x_margin=0):
return max(
0,
min(self.bbox[2] + x_margin, other.bbox[2] + x_margin)
- max(self.bbox[0] - x_margin, other.bbox[0] - x_margin),
)
def y_overlap(self, other, y_margin=0):
return max(
0,
min(self.bbox[3] + y_margin, other.bbox[3] + y_margin)
- max(self.bbox[1] - y_margin, other.bbox[1] - y_margin),
)
@property
def center(self):
return [(self.bbox[0] + self.bbox[2]) / 2, (self.bbox[1] + self.bbox[3]) / 2]
def __hash__(self):
return hash(tuple(self.bbox))
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from typing import Optional
import torch
from surya.common.load import ModelLoader
from surya.settings import settings
class BasePredictor:
model_loader_cls = ModelLoader
batch_size: Optional[int] = None
default_batch_sizes = {"cpu": 1, "mps": 1, "cuda": 1}
torch_dtype = settings.MODEL_DTYPE
@property
def disable_tqdm(self) -> bool:
return self._disable_tqdm
@disable_tqdm.setter
def disable_tqdm(self, value: bool) -> None:
self._disable_tqdm = bool(value)
def __init__(
self,
checkpoint: Optional[str] = None,
device: torch.device | str | None = settings.TORCH_DEVICE_MODEL,
dtype: Optional[torch.dtype | str] = None,
attention_implementation: Optional[str] = None,
):
if dtype is None:
dtype = self.torch_dtype
loader = self.model_loader_cls(checkpoint)
self.model = loader.model(device, dtype, attention_implementation)
self.processor = loader.processor()
self._disable_tqdm = settings.DISABLE_TQDM
def to(self, device_dtype: torch.device | str | None = None):
if hasattr(self, "model") and self.model:
self.model.to(device_dtype)
return
# Predictors that don't own a torch model (e.g. VLM-backed predictors that
# rely on an external server) treat .to() as a no-op.
if hasattr(self, "manager") and self.manager is not None:
return
raise ValueError("Model not loaded")
def get_batch_size(self):
batch_size = self.batch_size
if batch_size is None:
batch_size = self.default_batch_sizes["cpu"]
if settings.TORCH_DEVICE_MODEL in self.default_batch_sizes:
batch_size = self.default_batch_sizes[settings.TORCH_DEVICE_MODEL]
return batch_size
def __call__(self, *args, **kwargs):
raise NotImplementedError()
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from typing import Optional
from transformers import PreTrainedModel
from transformers.utils import is_flash_attn_2_available
class SuryaPreTrainedModel(PreTrainedModel):
# No-op if we pass attention, so we can set attention however we want in the config
def _check_and_adjust_attn_implementation(
self, attn_implementation: Optional[str], **kwargs
):
if attn_implementation is None:
try:
self._sdpa_can_dispatch(True)
attn_implementation = "sdpa"
except (ValueError, ImportError):
attn_implementation = "eager"
if self._supports_flash_attn and is_flash_attn_2_available():
attn_implementation = "flash_attention_2"
return attn_implementation
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import json
import os
import shutil
import tempfile
import time
from concurrent.futures import ThreadPoolExecutor
from pathlib import Path
import requests
from tqdm import tqdm
from surya.logging import get_logger
from surya.settings import settings
logger = get_logger()
# Lock file expiration time in seconds (10 minutes)
LOCK_EXPIRATION = 600
def join_urls(url1: str, url2: str):
url1 = url1.rstrip("/")
url2 = url2.lstrip("/")
return f"{url1}/{url2}"
def get_model_name(pretrained_model_name_or_path: str):
return pretrained_model_name_or_path.split("/")[0]
def download_file(remote_path: str, local_path: str, chunk_size: int = 1024 * 1024):
local_path = Path(local_path)
try:
response = requests.get(remote_path, stream=True, allow_redirects=True)
response.raise_for_status() # Raise an exception for bad status codes
# Get file size from headers for progress bar
total_size = int(response.headers.get('content-length', 0))
# Create progress bar with file name and size info
filename = local_path.name
pbar = tqdm(
total=total_size,
unit='B',
unit_scale=True,
unit_divisor=1024,
desc=f"Downloading {filename}",
miniters=1
)
with open(local_path, "wb") as f:
downloaded = 0
for chunk in response.iter_content(chunk_size=chunk_size):
if chunk:
f.write(chunk)
downloaded += len(chunk)
pbar.update(len(chunk))
pbar.close()
return local_path
except Exception as e:
if local_path.exists():
local_path.unlink()
logger.error(f"Download error for file {remote_path}: {str(e)}")
raise
def check_manifest(local_dir: str):
local_dir = Path(local_dir)
manifest_path = local_dir / "manifest.json"
if not os.path.exists(manifest_path):
return False
try:
with open(manifest_path, "r") as f:
manifest = json.load(f)
for file in manifest["files"]:
if not os.path.exists(local_dir / file):
return False
except Exception:
return False
return True
def download_directory(remote_path: str, local_dir: str):
model_name = get_model_name(remote_path)
s3_url = join_urls(settings.S3_BASE_URL, remote_path)
# Check to see if it's already downloaded
model_exists = check_manifest(local_dir)
if model_exists:
return
# Use tempfile.TemporaryDirectory to automatically clean up
with tempfile.TemporaryDirectory() as temp_dir:
# Download the manifest file
manifest_file = join_urls(s3_url, "manifest.json")
manifest_path = os.path.join(temp_dir, "manifest.json")
download_file(manifest_file, manifest_path)
# List and download all files
with open(manifest_path, "r") as f:
manifest = json.load(f)
pbar = tqdm(
desc=f"Downloading {model_name} model to {local_dir}",
total=len(manifest["files"]),
)
with ThreadPoolExecutor(
max_workers=settings.PARALLEL_DOWNLOAD_WORKERS
) as executor:
futures = []
for file in manifest["files"]:
remote_file = join_urls(s3_url, file)
local_file = os.path.join(temp_dir, file)
futures.append(executor.submit(download_file, remote_file, local_file))
for future in futures:
future.result()
pbar.update(1)
pbar.close()
# Move all files to new directory
for file in os.listdir(temp_dir):
shutil.move(os.path.join(temp_dir, file), local_dir)
class S3DownloaderMixin:
s3_prefix = "s3://"
@classmethod
def get_local_path(cls, pretrained_model_name_or_path) -> str:
if pretrained_model_name_or_path.startswith(cls.s3_prefix):
pretrained_model_name_or_path = pretrained_model_name_or_path.replace(
cls.s3_prefix, ""
)
cache_dir = settings.MODEL_CACHE_DIR
local_path = os.path.join(cache_dir, pretrained_model_name_or_path)
os.makedirs(local_path, exist_ok=True)
else:
local_path = ""
return local_path
@classmethod
def from_pretrained(cls, pretrained_model_name_or_path, *args, **kwargs):
# Allow loading models directly from the hub, or using s3
if not pretrained_model_name_or_path.startswith(cls.s3_prefix):
return super().from_pretrained(
pretrained_model_name_or_path, *args, **kwargs
)
local_path = cls.get_local_path(pretrained_model_name_or_path)
pretrained_model_name_or_path = pretrained_model_name_or_path.replace(
cls.s3_prefix, ""
)
# Retry logic for downloading the model folder
retries = 3
delay = 5
attempt = 0
success = False
while not success and attempt < retries:
try:
download_directory(pretrained_model_name_or_path, local_path)
success = True # If download succeeded
except Exception as e:
logger.error(
f"Error downloading model from {pretrained_model_name_or_path}. Attempt {attempt + 1} of {retries}. Error: {e}"
)
attempt += 1
if attempt < retries:
logger.info(f"Retrying in {delay} seconds...")
time.sleep(delay) # Wait before retrying
else:
logger.error(
f"Failed to download {pretrained_model_name_or_path} after {retries} attempts."
)
raise e # Reraise exception after max retries
return super().from_pretrained(local_path, *args, **kwargs)
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from typing import List
from surya.common.polygon import PolygonBox
def clean_boxes(boxes: List[PolygonBox]) -> List[PolygonBox]:
new_boxes = []
for box_obj in boxes:
xs = [point[0] for point in box_obj.polygon]
ys = [point[1] for point in box_obj.polygon]
if max(xs) == min(xs) or max(ys) == min(ys):
continue
box = box_obj.bbox
contained = False
for other_box_obj in boxes:
if other_box_obj.polygon == box_obj.polygon:
continue
other_box = other_box_obj.bbox
if box == other_box:
continue
if (
box[0] >= other_box[0]
and box[1] >= other_box[1]
and box[2] <= other_box[2]
and box[3] <= other_box[3]
):
contained = True
break
if not contained:
new_boxes.append(box_obj)
return new_boxes
def expand_bbox(bbox, expansion_factor=0.01):
expansion_low = 1 - expansion_factor
expansion_high = 1 + expansion_factor
return [
bbox[0] * expansion_low,
bbox[1] * expansion_low,
bbox[2] * expansion_high,
bbox[3] * expansion_high,
]