Hallucinations are problematic, and they're hard to defend against, if there's only one source of truth. I was surprised by the creativity that LLMs showed for the simple task of placing footnotes references, as I explain in the post.
.. But there's no harm in trying. At the very least it could be done in conjunction with traditional OCR to check for whole sentences of pure invention.
We have been using Gemini 1.5 Flash at enterprise scale on a massively varied, form based document dataset and we have yet to see hallucinations, on either our ground-truth dataset or in our random audits for evaluation. Just to make sure though we threw some recursion on it: we take the output and give it right back to the model with the original prompt and output and ask it how accurate it is. If it thinks it's not accurate we tell it to rewrite the original prompt to provide for a more accurate output. We then stuff that right back down its own function :)
For your use-case it would be exponentially easier as all you'd need to provide Gemini your "zones" as the JSON schema for output and it will quite reliably identify them.
I just tested Gemini 1.5 Flash (interactively on Google AI Studio) and the results are far from acceptable.
OCR seems good, on par with Google Vision.
But the footnotes are not properly identified on most pages; they are properly identified when there is a large gap and the first line of the footnotes starts with a number; but when the footnotes block starts with text (continuing a footnote from a previous page) and/or the gap is small or almost non-existent, it fails (all text on the page is considered belonging to main text).
But the main problem isn't even that, it's that it takes between 10 to 20 seconds per page. That would mean over three hours per volume of 600 pages. Google Vision takes less than one second per page.
It's possible there is a setup cost and that doing batches or even full PDFs would be better, though. Do you have experience with this? And can you maybe share "prompt secrets" that would improve the results...?
Gemini 1.5 pro worked better for me at Korean OCR on camera phone taken scans so must be better in some scenarios. You could try it but it's certainly slow.
{
"comments": "Guimaraes, son caractère et ses mœurs.",
"footnotes": [
"1. Voyez une lettre du général Marquis de Saint-Simon, dans le Moniteur, du 18 août 1838. — Cet ouvrage, cessionnaire de Boisange, eut vingt et un volumes in-8° par Sautel, publiés par Delloye, et celle de 1883, publiée par les frères Ducharne, quarante volumes in-18.",
"2. L'édition de 4820-4830, la publiée de l'édition de 1840.",
"3. Mémoires complets et authentiques du duc de Saint-Simon sur le règne de Louis XIV, et la Régence, collationnés sur le manuscrit ori- ginal par M. Chéruel, et précédés d'une notice par Sainte-Beuve, de l'Académie française. — Paris, 1856, in-8° de 1840 pages. — Cette édition est imprimée en deux volumes, sans faute, et avec une exactitude parfaite, en raison des volumes de 1861 ; un autre, dans le format in-42, ac- compagné de dix-un.",
"4. En treize volumes. — Un premier tirage, sans le concours ; un troi- sième, dans le format in-18, en 1883, et un quatrième en 1865, dans le format in-16.",
"5. Cette maison venait d'inaugurer sa Bibliothèque des chemins de fer, qui contribua beaucoup au succès de cette publication.",
"6. Sa propriété est particulièrement confirmée par des arrêts anté- rieurs à l'acquisition ; l'un du tribunal de première instance de Paris en date du 8 juin 1856, un autre de la Cour d'appel en date du 8 fé-"
],
"header": "MEMOIRES DE SAINT-SIMON.",
"main_text": "ce manuscrit, en y pratiquant toutefois ce qu'il appelait « les corrections et les retranchements indispensables ». Outre cette première édition, datée de 1829-1830, les Mémoires complets et authentiques du duc de Saint-Si- mon sur le siècle de Louis XIV et la Régence furent deux fois réimprimés par les soins du général de Saint-Simon en 1840 et 1856, avant que M. Chéruel obtint de faire l'édition de 1856, que depuis lors, on a considéré, non sur l'original une nouvelle revision ou d'ont sorties sans raison, comme édition principale, et plusieurs réim- pressions successives du texte sec, en moindre format, toutes faites par la maison Hachette³, qui devint propriétaire du manuscrit des Mémoires.",
"signature_mark": null
}
Also, if you're wondering why it output "Guimaraes, son caractère et ses mœurs." as a comment, it's because my instructions were not clear enough and it thought the prompt was asking for it to provide comment on the text :D
Yes I periodically try to get scanned images of Medieval Latin and Hebrew books ocr’d and translated by Gemini and ChatGPT… sometimes the results are amazing, but you have to proofread it all because they occasionally go off the rails. They will either skip sentences, or start regurgitating sentences from another similar text that they must have been trained on. Sometimes, after helping me with several pages, Gemini will suddenly decide to announce “I’m just an LLM, and I can’t process images”, and I have to encourage it to try anyway. It’s strange. Still overall a time saver.
As for segmenting the images (header/footer/table/main text) I’ve been using Abbyy and it’s generally pretty good at it. It unfortunately often fails at footnotes in much the same way as described in the post, so it won’t get you past that hurdle.
I've not done it at scale but so far I've had very good experience with OCR using AI models. Maintenance bill for my car in german: OCR, boom translation to french in no time. Works amazingly well.
