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

Despeckle filter in gamma space flattens subtle highlights (see e.g. the the shiny edge over the word "scale" in the lupe and the letter "c" in the word "scale".).

Linear space processing

1. Open the original linear higher bit-depth image.
2. convert to 8-bit mode.
3. apply Despeckle filer.
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 Despeckle filer.
5. save as jpeg using quality factor 4.