The camera uses a Foveon X3 sensor, which comprises 3 layers of 4800 x 3200 pixels (46 megapixels), giving much higher chromatic resolution than the equivalent Bayer array.

The Foveon sensor does not use an aliasing filter, thus further improving the resolution.

The SD1 was announced by Sigma at photokina 2010 on September 21, 2010.

[1] In February 2012, the SD1 was relaunched as the SD1 Merrill, honoring the late Richard B. Merrill, inventor of the Foveon sensor.

Sigma gave existing SD1 owners credit toward the company's lenses and accessories equal to the price cut.