The contrast of modern lenses, with extreme sharp borders is so high that they can out pass the human eye.
A contrast filter lowers the contrast and create “atmospheric” look by adding a glow and subtle haze around light sources. LowCon Filter mute the blacks by spreading light into the shadows and desaturate the image while Digicon raise the blacks and lower the highlights for more dynamic range. Contrast filter do not affect the mid tones. They keep resolution and desaturate the scene without softening or adding halos, as diffusion filters do. Highlight areas remain clean and halo-free.