In a verification data encoding method of the invention, a verification
data is provided for each of a plurality of pixels of a digital image, in
order for determining whether an alteration to the digital image is
effected. The verification data is inserted to each of the plurality of
pixels of the digital image such that the verification data is invisible.
In an original image verification method and apparatus of the invention, a
key information is input and a pseudo-random code is provided by taking
the pseudo-random code from a sequence of pseudo-random codes initialized
by the key information. A verification data is calculated through a
predetermined operation based on a pixel value indicated by a
predetermined number of bits of the pixel of concern in an input digital
image and based on the pseudo-random code. Then, it is determined whether
a value of the verification data matches with a value of the pixel of
concern in the input digital image, in order to determine whether an
alteration to an original digital image is effected, based on a result of
the determination.
