NLTE abundance corrections for representative lines of aluminium, computed at different metallicities with a NLTE reference abundance of [Al/Fe] = 0 for 1D MARCS models. The metallicity and line central wavelength (in units of Å) are indicated in the top left corner of each panel. Overplotted isocontours indicate the reduced line strength, log W_λ/λ. The white line delimits positive from negative abundance corrections, and the color scale is given in steps of 0.1 dex.