Patent ID: 7715071

Claim:
An apparatus for measuring color values of prints, having imaging means with a plurality of imaging elements arranged transversely of a print transport direction for imaging, at predetermined intervals, the prints transported by transport means, the apparatus performing a shading correction of image data from said plurality of imaging elements by using a white preliminary reference value and a black preliminary reference value obtained by imaging a white reference plate and a black reference plate with said imaging means, said apparatus comprising: control means for variably controlling a print transport speed of said transport means; storage means for storing a relationship between said print transport speed and said white preliminary reference value and said black preliminary reference value corresponding to said print transport speed; and correcting means for correcting color values obtained by imaging the prints with said imaging means, by using a white reference value and a black reference value corresponding to an actual print transport speed obtained from a print transport speed in time of actual printing and the relationship, stored in said storage means, between said print transport speed and said white preliminary reference value and said black preliminary reference value corresponding to said print transport speed, wherein the following equations are established: W ⁢ ⁢ b = [ ( A × L Vp L Vw ) + B ] × Wa + [ ( C × L Vp L Vw ) + D ] ( 1 ) Bb = [ ( E × L Vp L Vb ) + F ] × Ba + [ ( G × L Vp L Vb ) + H ] ( 2 ) Pb = I ( W ⁢ ⁢ b - Bb ) × ( P ⁢ ⁢ a - Bb ) ( 3 ) where L is said predetermined intervals, Vw is a transport speed of said white reference plate, Vb is a transport speed of said black reference plate, Vp is said print transport speed, Wa is said white reference value, Ba is said black reference value, Pa is said color values, Wb is a corrected white reference value corresponding to said print transport speed, Bb is a black reference value converted into a value corresponding to said print transport speed, Pb is corrected color values, and A through I are constants.