The original in 16-bit mode is linear 12-bit acquire using Canon eos*dcs3 camera into Photoshop 15-bit space and then cropped.

Mosic filter in gamma space darkens the image in overall and introduces hue-shifts.

Linear space processing

1. Open the original linear higher bit-depth image.
2. convert to 8-bit mode.
3. apply Mosaic filter at Cell size =5.
4. apply inverse gamma 2.2.
5. save as jpeg using quality factor 4.

Gamma-space processing

1. Open the original linear higher bit-depth image.
2. apply inverse gamma 2.2.
3. convert to 8-bit mode.
4. apply Mosaic filter at Cell size =5.
5. save as jpeg using quality factor 4.