Which OCR engine does it use?

None. There is no OCR engine in this application, so no text is extracted here and none is invented. The tool reads the image header to report format, dimensions and DPI, tells you whether the image is good enough to OCR, and gives you the exact tesseract or ocrmypdf command to run. Paste the output back in and it cleans it up.

Does it support non-Latin scripts?

Tesseract supports 100+ languages including Arabic, Chinese, Japanese, Korean, Devanagari, and Cyrillic. Select the language before processing for optimal accuracy with the relevant script.

What image formats does it accept?

PNG, JPEG, TIFF, BMP, GIF, and WebP. For best results, use PNG (lossless compression, no JPEG artifacts). Minimum recommended resolution is 300 DPI equivalent.

OCR Simulator | DevTools Surf

DevTools Surf

Example: OCR Simulator

A worked example, rendered from real sample data. Sign in to run the tool on your own input.

Input

image: invoice-scan-p1.png
bytes: 500
data:image/png;base64,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

Output

═══ What this tool did ═══
✗ No text was extracted from this image. There is no OCR engine in this application — not tesseract, not a cloud API, nothing. Any tool that returned you a paragraph of text here would be inventing it.
✓ What it did do is read the image header itself and work out whether the image is good enough to OCR, and with which settings.

═══ Image you attached ═══
File: invoice-scan-p1.png
Size on disk: 500 bytes
Format: PNG
Dimensions: 640 × 200 pixels (0.13 MP)
Pixel format: 8-bit greyscale
Resolution: 300 DPI (declared in the file)

═══ Is this image good enough to OCR? ═══
⚠ 200px on the short edge is small. A full page at 300 DPI is about 2550 × 3300 — this is well under that, so expect character errors in anything below about 12pt.
Implied resolution if this is a full A4 page: about 300 DPI.
✓ That is in the range tesseract is trained for.
ℹ Order that actually matters: greyscale first, then deskew, then a threshold. Sharpening a blurry scan adds ringing and makes OCR worse, not better.

═══ Commands that actually extract the text ═══
  tesseract input.png output -l eng --psm 6 --dpi 300 && cat output.txt
  tesseract input.png - -l eng+deu --psm 4            # two languages, one column per block
  tesseract input.png out hocr                        # word boxes + per-word confidence
  ocrmypdf --force-ocr --deskew --clean in.pdf out.pdf
  pdftotext -layout in.pdf -                          # try this FIRST: a digital PDF needs no OCR at all
  magick input.png -colorspace gray -resize 300% -unsharp 0x1 -threshold 60% prepped.png
  shortcuts run 'Extra
…

About OCR Simulator

Read an image's real header, get the right tesseract command for it, and clean up the OCR text you paste back — no text is extracted here. Part of the DevTools Surf developer suite. Browse more tools in the Images collection.

Use Cases

Estimate OCR accuracy for a document digitization project before committing to a processing pipeline.
Test which image pre-processing steps (binarization, deskew, denoising) improve recognition on your document type.
Check a scan's real dimensions and DPI before sending a batch through tesseract.
Clean up tesseract output: rejoin hyphenated line breaks and soft-wrapped paragraphs, normalise ligatures, and flag O/0 and l/1 confusions.

Tips

Pre-process images before OCR: increase contrast, deskew scanned documents, and resize to at least 300 DPI equivalent — these steps improve accuracy more than algorithm selection.
Run pdftotext -layout first on any PDF: if it was produced digitally the text is already in there and OCR would only make it worse.
Test OCR output on a sample before building a pipeline — accuracy on printed text (95-99%) differs significantly from handwritten text (70-90% for modern models).

Fun Facts

OCR (Optical Character Recognition) dates to 1914, when Emanuel Goldberg built a machine that could read characters and convert them to telegraph code. Commercial systems became available in the 1950s for reading bank checks.
Google's Tesseract OCR engine, originally developed at HP Research Labs in 1985 and open-sourced by Google in 2005, achieved a breakthrough in 2018 when LSTM (deep learning) models raised accuracy from ~86% to 97%+ on printed text.
Chinese character OCR is significantly harder than Latin alphabet OCR: standard Chinese uses 3,500 common characters (20,000+ total) vs. 26 letters, requiring neural networks trained on an order of magnitude more character classes.

FAQ

Which OCR engine does it use?: None. There is no OCR engine in this application, so no text is extracted here and none is invented. The tool reads the image header to report format, dimensions and DPI, tells you whether the image is good enough to OCR, and gives you the exact tesseract or ocrmypdf command to run. Paste the output back in and it cleans it up.
Does it support non-Latin scripts?: Tesseract supports 100+ languages including Arabic, Chinese, Japanese, Korean, Devanagari, and Cyrillic. Select the language before processing for optimal accuracy with the relevant script.
What image formats does it accept?: PNG, JPEG, TIFF, BMP, GIF, and WebP. For best results, use PNG (lossless compression, no JPEG artifacts). Minimum recommended resolution is 300 DPI equivalent.

Related Images Tools

Sample Images Image Converter Bulk Image Converter Image Editor Aspect Ratio Calculator SVG Optimizer Favicon Generator Lorem Picsum Picker