Basic

grayscale
color
paletted
grayscale + alpha
color + alpha

Image filtering

grayscale, filter 0
color, filter 0
grayscale, filter 1
color, filter 1
grayscale, filter 2
color, filter 2
grayscale, filter 3
color, filter 3
grayscale, filter 4
color, filter 4

Transparency

grayscale, not transparent
color, not transparent
paletted, not transparent
color, transparent
paletted, transparent