A clear answer. Here’s how.
Downsamples the image to ceiling(width/block) × ceiling(height/block) with browser canvas smoothing, then enlarges to original dimensions with nearest-neighbour sampling. Edge block widths may differ. Retains transparency. This is an editable visual effect and should not be assumed to securely anonymise faces or confidential details. Supports PNG/JPEG/WebP up to 10 MB and 4 million decoded pixels per file. Browser decoding and single-frame PNG re-encoding remove source metadata/colour profiles; no files leave this device.