Patent ID: 7358983

Claim:
A printing apparatus for printing an image onto a recording medium based on input image data, comprising: an electrostatic latent image carrier for forming an electrostatic latent image; and an exposure controller for forming said electrostatic latent image corresponding to one pixel upon exposure of said electrostatic latent image carrier with a combination of a plurality of different exposure amounts, wherein said exposure controller performs said exposure with said combination of said plurality of exposure amounts in a manner to satisfy a condition for an index value LNR expressed by a following general equation (1) using an optical density od (n) standardized on the condition of the maximum optical density equal to 1.0, identification information comb assigned to identify each combination of said plurality of exposure amounts, and the number of varieties m of a cumulative exposure amount used for modulation of said image data LNR ≤ 2 / m ⁢ ⁢ LNR ⁡ ( comb ) = ∑ n = 0 m - 3 ⁢ [ { ( od ⁡ ( n + 2 ) - od ⁡ ( n + 1 ) ) - ( od ⁢ ( n + 1 ) - od ⁡ ( n ) ) } 2 ] / ( m - 2 ) . ( 1 )