For each totally black pixel of image data to be printed using a fluid-ejection printing device, it is determined whether the pixel is part of a line feature or an area fill feature of the image data. Where the pixel is part of a line feature, a first printing mask selected that is optimized for printing line features. Where the pixel is part of an area fill feature, a second printing mask is selected that is optimized for printing area fill features. Each mask specifies a number of fluid droplets to be printed and positions where the fluid droplets are to be printed. The selected mask is applied to the pixel. The pixel is printed using the mask that has been applied. The fluid-ejection printing device prints the pixel by ejecting the number of fluid droplets specified by the mask at the positions specified by the mask.