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IMG4 tools

Image tools

Every tool in this category is a decode, an operation on pixels, and an encode. That is worth saying plainly, because it is also the source of every limitation on these pages. Decoding costs memory — roughly four bytes per pixel, so a fifty-megapixel photograph occupies about two hundred megabytes before anything happens to it. Encoding a JPEG is lossy, so a second pass over an already-compressed file compounds the damage rather than repeating it. And the canvas round-trip that does the work discards EXIF, which strips your GPS coordinates as a useful side effect and drops your colour profile as an inconvenient one.

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How this category works

All four run in your browser. The image is decoded into an ImageBitmap on a worker thread, drawn to an OffscreenCanvas, and re-encoded — none of which requires a server, and none of which happens on one here. Background removal is the interesting case: it runs a segmentation model on your own device rather than sending the photograph to a GPU somewhere. That costs about 95 MB of download the first time — measured, not estimated — and nothing starts downloading until you press the button.

Choosing between the tools is mostly a question of what the receiving system rejected. A file too large for an upload form wants compression. A file with the wrong dimensions wants resizing — and resizing to the size an image will actually be displayed at is almost always a bigger saving than compressing an oversized original. A file in a format the other system has never heard of wants conversion, which for iPhone photographs means HEIC to JPG. A product photo the marketplace will not list wants its background removed.

The honest caveats are on each page rather than collected here, but two are worth repeating. Enlarging an image past its original resolution adds no detail, whatever the output dimensions say. And stripping metadata is not the same as anonymising a photograph — the pixels still show what they show, and the place is still recognisable if it was recognisable before.

Every tool in image tools

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