The Ricoh GR IIIx HDF is a specialised variant of the GR IIIx, distinguished by its built-in Highlight Diffusion Filter (HDF) — a unique optical feature that softens and diffuses bright highlights to create a dreamy, ethereal quality that sets it apart from conventional compact cameras. The HDF can be toggled on or off with a single dedicated button — the rear Fn button is pre-configured for this function and labelled accordingly, though it can be reassigned to other controls if preferred. Beyond the filter itself, the GR IIIx HDF also features a silver-coloured shutter release button, offering a subtle yet distinctive visual identity compared to other cameras in the GR III series. All the core strengths of the GR IIIx remain intact: a 24.2MP APS-C sensor, a 40mm-equivalent prime lens, hybrid autofocus, built-in Shake Reduction, and a slim, pocketable body purpose-built for street and everyday photography.