Phone cameras emit 12+ MP images (~4000 px long edge). Tesseract
on a full-resolution shot was painfully slow — minutes, not
seconds. Downscaling to 1600 px on the long edge before
worker.recognize() makes OCR 4-8× faster with no real accuracy
loss for printed text.
Implementation: createImageBitmap -> draw to a sized HTMLCanvas
-> canvas.toBlob() at JPEG 0.85. Smaller-than-1600 px inputs are
passed through unchanged. Status line briefly shows the
downscale ratio so the timing is interpretable.
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