Experimento con emscripten y SDL
width=80
height=80
sand_bg=#c3a52e
sand_fg=#987405
convert -size ${width}x${height} xc: +noise Random -virtual-pixel tile -auto-level -channel G -threshold 15% -separate +channel -negate temp.png
convert temp.png -alpha copy -fx '#fff' sand.png
convert sand.png +level-colors black,${sand_fg} -blur 0x0.8 sand.png
convert -size ${width}x${height} canvas:${sand_bg} test.png
convert test.png sand.png -composite png32:sand_tile.png