Gray scale levels are converted to pseudo halftone print by a pseudo halftone generator which reduces Moire effects. The generator includes a comparator and an incrementing cyclic counting mechanism to compare the gray scale level to the cyclicly generated reference count for each print position in a print line to generate a print signal upon the level being greater than the count. The cyclicly generated count is incremented by a preselected number N for each print position and recycles at the square of that number (N.sup.2). The square value may also be selected as the maximum level of the gray scale range. N adjacent print lines may be grouped together to form a series of (N.times.N) matrices. The reference or lowest count value for each of the lines in a matrix is different and they range from zero to N-1. The arrangement of the lines in the matrix is such as to minimize the difference between the sums of the count element values for any two adjacent print lines. The count for each generator is initialized at the beginning of the print line and may be established randomly for each print line or, alternatively, for each matrix of print lines, the matrix being arranged in a predetermined manner.

An apparatus is provided for generating a random (mezzotint) screen for producing halftone copies of continuous tone documents. The random screen comprises a matrix of random numbers representing a sequence of digital reference values with respect to which video (scan) signals are compared for producing halftone picture elements (pels). The apparatus comprises a first and a second random number generator, the first being disposed for providing an initial or starting state for the second, in response to applied clock pulses. Using the supplied starting state, the second random number generator produces the random screen reference values in response to applied clock signals. The random screen reference values produced by the apparatus permits minimum halftone dot size (i.e., the size of the dot used in producing halftone images) to be varied, and halftone patterns to be selectively repeated or not repeated.

An image scanning and recording method wherein a random pulse signal is added either to the image signal obtained by scanning a continuous tone original or to the dot signal controlled synchronously with the scanning of the original. The image signal and the dot signal are compared with each other to obtain a randomized dot image signal. A light beam is on-off modulated by a light modulator in accordance with the randomized dot image signal, and a photosensitive recording medium is scanned with the on-off modulated light beam so as to record thereon a dot image corresponding to the continuous tone original. The random pulse signal is added to a peak portion and/or a middle level portion of the dot signal. Alternatively, the random pulse signal is added contiguously either to the whole dot signal or to the whole image signal.

An apparatus for processing an image having half-tone and composed of plural pixels by dividing each of said pixels into small sections arranged in a matrix and respectively constituting micro-pixels with luminosity that can be respectively designated according to a determined gradation, by representing the luminosity to be designated to each of the first-mentioned pixels by the luminosity in the form of systematic dither method for the plural micro-pixels in said pixel.

In a picture processing method according to the present invention, a picture element S(i,j) to be processed is divided into four smaller picture elements S.sub.1 (i,j) through S.sub.4 (i,j). The density of each of the smaller picture elements is determined from the algebraic mean value of the densities of the picture element and the picture elements surrounding the firstly mentioned picture elements. Each smaller picture element S.sub.m (i,j) (m=1,2,3, and 4) is determined by a DITHER MATRIX T(k,l) as S.sub.m (i,j)=1 when S.sub.m (i,j).gtoreq.T(k,l) and S.sub.m (i,j)=0 when S.sub.m (i,j)<T(k,l) where, using Gauss' notation, and