Remidesbois/LightonOCR-2-1b-poneglyph-bbox

LightOnOCR-2-1B Poneglyph BBox

Fine-tuned version of `lightonai/LightOnOCR-2-1B-bbox-base` for full-page French manga OCR with text-zone bounding boxes.

The model receives only an image and generates one text zone per line:

Texte exact [x1,y1,x2,y2]

Coordinates are integers normalized to `[0,1000]` in the image reference frame. The model is trained to preserve Japanese manga reading order and to return no JSON, Markdown, prefix or commentary.

Final held-out benchmark

Evaluation was run on the complete held-out test split: 221 pages, 1,920 annotated text zones. The model generated 1,903 zones (99.11% of the GT count).

The table below reports the corrected global metrics. These are recomputed from every raw page prediction in benchmark_lighton_bbox.json; the full values and definitions are stored in `benchmark_lighton_bbox_corrected.json`.

Metric definitions

• —Page CER (macro): CER computed on the complete serialized page output, then averaged over pages. Reading-order mistakes therefore count as OCR sequence errors.
• —Page CER (character-weighted): the same full-page comparison, aggregated by reference character count.
• —Global mean IoU: one-to-one maximum-IoU assignment over all predictions and GT zones; unmatched GT zones contribute IoU 0. This avoids inflating IoU by averaging only detections that already pass a threshold.
• —Precision / recall / F1: micro-aggregated across the complete test split at the stated IoU threshold.
• —Exact bubble text: exact text-content matches after one-to-one text assignment, independent of bbox quality and serialized page order.
• —Bubble-text CER: OCR error after bubble-text assignment, weighted by reference character count.

The corrected combined score keeps the training benchmark weighting but uses the corrected global metrics:

0.4 * (1 - Page_CER_macro)
+ 0.3 * F1@0.5_micro
+ 0.2 * Global_Mean_IoU
+ 0.1 * Recall@0.5_micro
= 0.8257147803

The original metrics_version=2 fields remain available in benchmark_lighton_bbox.json for reproducibility. In particular, its legacy mean_iou averages only IoU>=0.5 matches and should not be interpreted as a global mean IoU.

Dataset

Human-validated Poneglyph full manga pages were split by page:

Images are processed with a 1,500 px longest edge while keeping their aspect ratio. Bboxes are normalized to [0,1000].

Training

The final run was trained locally on an NVIDIA GeForce RTX 5090 32 GB.

The LoRA adapters were merged into the final weights published in this repository.

Inference

import torch
from PIL import Image
from transformers import LightOnOcrForConditionalGeneration, LightOnOcrProcessor

MODEL_ID = "Remidesbois/LightonOCR-2-1b-poneglyph-bbox"
IMAGE_PATH = "page.jpg"

processor = LightOnOcrProcessor.from_pretrained(MODEL_ID)
processor.image_processor.default_to_square = False

model = LightOnOcrForConditionalGeneration.from_pretrained(
    MODEL_ID,
    torch_dtype=torch.bfloat16,
    device_map="auto",
)
model.eval()

image = Image.open(IMAGE_PATH).convert("RGB")

# Image-only conditioning: do not add a textual user prompt.
messages = [
    {
        "role": "user",
        "content": [{"type": "image"}],
    }
]

prompt = processor.apply_chat_template(
    messages,
    add_generation_prompt=True,
    tokenize=False,
)

inputs = processor(
    text=[prompt],
    images=[image],
    size={"longest_edge": 1500},
    return_tensors="pt",
)

device = next(model.parameters()).device
inputs = {
    key: value.to(device=device, dtype=torch.bfloat16)
    if value.is_floating_point()
    else value.to(device)
    for key, value in inputs.items()
}

with torch.inference_mode(), torch.autocast("cuda", dtype=torch.bfloat16):
    output_ids = model.generate(
        **inputs,
        max_new_tokens=1280,
        do_sample=False,
        use_cache=True,
    )

generated = output_ids[:, inputs["input_ids"].shape[1]:]
text = processor.batch_decode(generated, skip_special_tokens=True)[0].strip()
print(text)

Example output:

Je serai le roi des pirates !! [684,102,919,191]
Allons-y. [112,713,251,769]

To map a normalized bbox back to pixels for an image of width W and height H:

x1_px = x1 * W / 1000
y1_px = y1 * H / 1000
x2_px = x2 * W / 1000
y2_px = y2 * H / 1000

Benchmark artifacts

• —benchmark_lighton_bbox.json: raw final benchmark with all 221 page predictions and the legacy metrics emitted by the training pipeline.
• —benchmark_lighton_bbox_corrected.json: corrected global/micro metrics derived from those same predictions, including metric definitions and the combined-score formula.

Limitations

• —Fine-tuned primarily on French One Piece manga pages; generalization to other manga, languages or layouts is not guaranteed.
• —Very strict bbox localization remains the main limitation: F1 is 79.62% at IoU 0.5 but 41.75% at IoU 0.75.
• —Full-page CER is sensitive to reading-order mistakes even when individual bubble transcription is correct.
• —The model may occasionally miss, duplicate or reorder small text zones.

Base model

Fine-tuned from LightOnOCR-2-1B-bbox by LightOn.

@misc{lightonocr2_2026,
  title        = {LightOnOCR: A 1B End-to-End Multilingual Vision-Language Model for State-of-the-Art OCR},
  author       = {Said Taghadouini and Adrien Cavailles and Baptiste Aubertin},
  year         = {2026},
  howpublished = {https://arxiv.org/abs/2601.14251}
}

License

Apache 2.0, following the base model license.