The Sigma SD1 is a digital SLR camera produced by the Sigma Corporation of Japan. 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. It uses a Milbeaut image processor. The Foveon sensor does not use an aliasing filter, thus further improving the resolution.
In February 2012, the SD1 was relaunched as the SD1 Merrill, honoring the late Richard B. Merrill, inventor of the Foveon sensor.