Why PNG at 200KB? Aadhaar signature & Voter ID scans
The SSUP Aadhaar self-service portal accepts signature and thumb-impression PNGs up to 200 KB, and the Voter Service Portal uses the same cap for uploaded documents. PNG is required rather than JPG because the OCR verification step needs sharp edges, and 200 KB gives enough headroom for a 600×400 signature at 8-bit depth.