Building a Browser-Only Image Compressor: What We Actually Measured
Building a Browser-Only Image Compressor: What We Actually Measured Most "online image compressor" pages upload your file, compress it on a server, and hand back a download link. That works, but it costs you two things: your file leaves your machine, and the result depends on someone else's queue depth. We wanted the opposite: the pixels never leave the browser. Here is what that looks like in…
The article discusses the creation of a browser-only image compressor that performs image compression without uploading files to a server. This approach addresses privacy concerns and eliminates the dependency on server queues. The compressor uses WebAssembly-based encoders and Canvas for pixel work, supporting various formats such as PNG, JPEG, WebP, AVIF, and GIF.
The author tested the compressor on five representative images, measuring the original size, lossless compression, quantized compression, and WebP format size. The results showed that the compressor can save up to 96.6% for full-color PNGs and 76.2% for JPEGs. The author concludes that the gain depends on the routing method rather than the tool itself, and format flexibility can significantly improve compression results.
However, large images are limited by the device's capabilities, and the compressor's performance can be improved by downsampling before encoding and using worker pools with OffscreenCanvas.
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