Overcoming JPEG Compression Noise in OCR
JPG images use lossy discrete cosine transform compression that introduces noise rings around sharp letter contours. Our JPG converter applies an automated spatial filter to smooth compression halos before character classification.
How JPEG Quality Levels Affect Text Recognition
JPEG quality settings range from 1 to 100. Files saved below quality 60 show visible blocking artifacts around text edges, which reduces OCR accuracy. At quality 80 and above, character boundaries remain sharp enough for reliable recognition. If you control the export settings, save at quality 85 or higher. For images already saved at low quality, the converter applies a low-pass filter to reduce block boundaries before binarization. This recovers roughly 10 to 15 percent of lost accuracy on heavily compressed files.
Best Practices for Scanning Documents as JPG
When scanning paper documents to JPG, set your scanner to 300 DPI or higher. Use grayscale mode for black-and-white documents, as it produces smaller files without color channel noise. Avoid scanning at an angle. Even a 2-degree skew forces the OCR engine to rotate the image, which can blur thin strokes. Place the page flat against the scanner glass and close the lid to block ambient light. After scanning, check the file size. A single A4 page at 300 DPI grayscale should be between 200 KB and 1 MB in JPG format. Files much smaller than this were likely over-compressed.