Method and apparatus are provided for controlling a group of ink-jet printing heads to selectively apply (or not apply) dots of one color and of substantially fixed size in random dot pattern arrangements to dot positions of a plurality of pixel areas located sequentially along a line scanned by the printing heads. A sequential series of F integral value color image density signals representative of the tone value at which a respective one of the pixel areas is to be printed by the colored dots is produced. A number of different dot pattern arrangements are listed in a table for the F integral values to produce the tone value representative of a density signal of such an integral value. One of the dot pattern arrangements is randomly selected whenever a color density signal of the integral value appears. The group of ink-jet heads apply colored dots onto the dot positions of the associated pixel area in accordance with the pattern randomly selected.

Method and apparatus for controlling ink-jet color printing heads

A method and apparatus for converting the resolution of an input image to a higher resolution that is a noninteger multiple of the input resolution. The method and apparatus employ either an interlocked or noninterlocked clustering arrangement of output pixels in order to assign to each output pixel a reference value determined from the signal levels of the input image. In addition, the method and apparatus include a template-based enhancement filter to further refine modify or alter the assigned signal level prior to its output as a higher resolution image.

Area mapping employing reference clusters for high quality noninteger resolution conversion with enhancement

A method for recording an image by scanning a photosensitive recording medium with a light beam wherein a number of image region are designated on an original image and the image regions are electrically processed using certain image processing conditions which are different for each designated image region in said original image. The image processing conditions comprises different gradation, sharpness, magnification or halftone mode adjustments for each of the designated image regions or any combination of two or more of said image processing conditions.

Image scanning and recording method

An image processing apparatus and method for processing color image signals. The apparatus comprises a first judgment unit for judging whether or not a pixel of interest belongs to a black line image portion, and outputting a first judgment signal indicating a judgment result, a second judgment unit for judging whether or not pixels in the vicinity of the pixel of interest belong to a black line image portion, and outputting a second judgment signal indicating a judgment result, and a control unit for controlling recording of the pixel of interest based on the first and second judgment signals outputted from the first and second judgment units. With the apparatus, black lines in a color image are satisfactorily reproduced.

Image processing method and apparatus

Halftone dots are formed on the basis of three sets of screen pattern data assigned to the to a same combined area, in which a plurality of halftone dots are to be formed. The three sets of screen pattern data have different threshold values assigned to respective pixels in the combined area, and are stored in SPM's (101-116). Eight SPM's (Screen Pattern memory units) store a first set of the screen pattern data, six SPM's store a second one, end two SPM's store a third one. One of the sixteen SPM's is randomly selected with respect to each pixel, whereby one of the threshold values (D s ) stored in the selected SPM is compared with an iamge signal (V 1 ). A dot signal indicating whether or not each pixel is solid is produced on the basis of the comparison. Accordingly, a grid-like pattern of halftone dots to be seen in a highlight area or a shadow area is prevented.

Method of and apparatus for forming halftone dots

A first pseudo-halftone picture is converted to a second pseudo-halftone picture of reduced resolution in the ration m:n by dividing the first picture into contiguous picture fields each having i·n lines and j·n columns of picture elements in contiguous square subfields each having n 2 picture elements. m 2 elements are selected from each subfield in accordance with a selection sequence which depends on the position of the subfield in the picture field, the elements being selected from all i·n lines and all j·n columns of each picture field, the selection sequence being the same for each picture field.

Method of and circuit arrangement for changing the resolution of binary pseudo-halftone pictures

In practice it is often desirable to represent only a given, selectable dynamic range of a measuring signal, preferably in logarithmic form. This is achieved in accordance with the invention in that from the measured value in the form of a binary number only the positions corresponding to the desired dynamic range are selected for forming the base number, the weight of the most significant bits having the value "1" being converted into a binary number. The mantissa is derived from the following positions, i.e. independent of the selected dynamic range, so that even when the most significant bit is in the last position, a mantissa comprising the full number of positions is formed. The magnitude of the dynamic range is chosen by omitting the correspondingly more significant positions of the base number formed for the maximum range. The position of the dynamic range can be shifted in that the inputs of the circuits for forming the base number and the mantissa are shifted with respect to the lines supplying the individual positions of the measured value.

Natural binary to logarithmic binary conversion device with means for range selection

Method and apparatus for producing a grey-tone image having areas of different average density values which are given by an n-digit binary number, all the bits of the binary number being interrogated in parallel by clock patterns. For the area to be printed an elemental area containing 2 n pulses is selected which is printed in a total cycle of 2 n - 1 clock pulses of the clock pattern. In this total cycle, at each clock pulse the drive of each pair of dots is determined in a manner such that the most-significant bit of the binary number is always used for driving while the remaining bits are used a number of times which depends upon their positional values. For this purpose, for each position of the binary number the clock pattern has a number of clock pulses which corresponds to the value of this position. The clock pulses for the individual positions are non-uniformly distributed in time, however, no clock pulses for the second and any further positions of the binary number coincide in time. Before each new print line the pattern will if required be shifted by additional clock pulses.

Logic circuit for grey-tone printer

Verfahren und schaltungsanordnung zur aufloesungsumwandlung von binaeren pseudo-halbtonbildern

An apparatus for the magnetic brush development of electrostatic latent charge images on single-sheet recording carriers (11) contains inside a rotating cylinder (28), which carries the magnetic brush, a magnet arrangement (31) which during the time that the recording carrier (11) is being moved with its front edge into the development region (B) can be brought into a position in which it does not produce any magnetic brush in the development region (B). This prevents the rear of the recording carrier (11) from becoming contaminated with developer material as the front edge enters the development region (B). The adjustment is cancelled as soon as the recording carrier (11) has reached a position in which developer material can no longer reach its rear.

Bernd Ehlers

Papers

Method of and circuit arrangement for changing the resolution of binary pseudo-halftone pictures

Natural binary to logarithmic binary conversion device with means for range selection

Logic circuit for grey-tone printer

Verfahren und schaltungsanordnung zur aufloesungsumwandlung von binaeren pseudo-halbtonbildern

Magnetic brush development apparatus