1. having the most grainy texture or appearance; most rough or coarse in feel
Usage: superlative form of grainy
2. having the poorest image quality with the most visible grain or pixels
Usage: photography; digital imaging

Examples

• This is the grainiest sandpaper I’ve ever felt.
• The old photograph was the grainiest one in the album.
• Of all the wood samples, this oak has the grainiest surface.
• The video quality was grainiest during the night scenes.
• She chose the grainiest mustard for extra texture.
• The grainiest part of the wall needed more sanding.