Images produced by Sigma’s SD and DP series cameras have what’s been called an “emotional quality”. This phrase expresses the distinctive image-quality you only get with the Foveon X3® direct image sensor. In terms of clarity and fine detail, it goes far beyond the capabilities of conventional digital cameras. This level of image quality reproduces the scene you shot, right down to the feeling in the air. It’s only possible in a vertical color-capture system that does not require color interpolation, and an image-processing system that does not require an optical low-pass filter.
A conventional image-sensor, on the other hand, fudges the colors, and even cuts out high-frequency areas. To compensate, the sharpness processing is ramped up to give some overall nuancing and a general impression of high resolution. This explains the tendency to generate images that, as a whole, have an unnatural feel. The colors can be adjusted to some extent in post-processing, but the detailed data previously lost cannot be recovered. No wonder the images produced by conventional digital cameras, despite their emphasized edges and clever nuancing, look so unnatural, so subtly wrong, It’s all about basic principles.