FR2516329A1 - METHOD FOR ELECTRONIC RECORDING OF SEMI-SHINED IMAGES - Google Patents

Abstract

PROCESS FOR ELECTRONIC RECORDING OF A CONTINUOUS MODEL IMAGE, TO BE USED IN A CONTINUOUS MODEL IMAGE REPRODUCTION MACHINE TO MAKE TRAM CLICHES. A PLURALITY OF HALF-TINT DATA CORRESPONDING TO A PLURALITY OF IMAGE ELEMENTS OF A DEGRADED HALF-TONE POINT ARE SIMULTANEOUSLY EXTRACTED FROM A MEMORY 27 IN WHICH THE QUANTIFIED DEGRADED HALF-TONE POINT IS RECORDED, IN SYNCHRONIZED WITH IMAGE SIGNALS; HALF-SHADE DATA AND IMAGE SIGNALS ARE ADDED TO OBTAIN RECORD SIGNALS AND ACCORDING TO RECORD SIGNALS, A PLURALITY OF EXPOSURE LIGHT BEAMS ARE CONTROLLED TO BE PRESENT OR ABSENT, WHICH ALLOWS TO RECORD A HALF-TONE IMAGE. THE NUMBER OF LIGHT BEAMS INCLUDED IN A RECORDING SCAN WIDTH IS SELECTED ACCORDING TO A FRAME PITCH, AND THE SELECTED LIGHT BEAMS ARE CONTROLLED ACCORDING TO THE RECORDING SIGNALS.

Description

Electronic image recording method in half

  Hue-. The present invention relates to a method for electronically recording a halftone image for use in an image reproduction machine

  in half-tone to make clichés.

  In a proposed image reproduction machine

  previously, which reproduces electronically and directly

  a halftone image to transform signals

  image having a continuous gradation in recording signals

  for recording a halftone image or a halftone image, halftone signals equivalent to those obtained by scanning a contact frame are generated in addition, and image signals and image signals are generated. halftone are added consecutively to obtain the recording signals for recording the snapshot

halftone.

  With regard to the means for generating the half-tone signals, a variety of means have been proposed, and mainly using means using a semiconductor memory since recently, because of the increase in capacity and price decrease in semiconductor memory.

  However, when using semi-

  conductors, a halftone dot corresponding to a point

  degraded halftone of a contact frame by similar

  engraving is quantified and recorded there.

  main structure of the raster structure composed of the semitint signals that are generated by the memory

  semiconductor is determined in advance according to the conditions

  These conditions are, for example, frame angles, density steps or gradation, frame pitch factors, and the like. The frame angle 9 must satisfy a condition tg G = k, om and k are integers, when the degraded halftone dot is quantized. The density steps are determined according to a number S of d elements. image included in a region of degraded halftone dots, which will be referred to hereinafter as "unit area of halftone dots", and the maximum density steps are obtained when the number of pixels check the relation S = m 2 + k 2. The frame pitch P corresponds to a square root of

  the unit area of halftone dots, since the structure

  halftone pattern includes a repeating pattern of the

  square gradient halftones Thus, in the half structure

  quantized hue, the square root of the total number of pixels included in the unit area of halftone dots, i.e., = Vm 2 + k 2, is determined as a factor However, in color printing, in general, quadrichrome halftone pictures are used with a series of frame angles such as O,

  450, 150 and 75 and their pitch P need to

  However, when the point of half-

  degraded hue is quantized, the correct conditions described above are given for each frame angle and it is, therefore, very difficult to make equal

  the weft pitches P corresponding to all the frame angles.

  For example, when the condition tg o = k to obtain the frame angle O is determined by tg = m when the frame angle is 00, tg 45 = m 45 When -km 45 k the frame angle is 450 and tg 15 = mi when the screen angle is 150, the respective number of pixels 50, 545 and 515 and the respective factors Ko, O <45 and K 1 are obtained for the screen pitches as follows SO = mo 2 <o = io = Mo 545 = 2 m 452, <45 X 2 f 515 = m 152 + k 2 <152 g = 2 m 2+ k 2 With respect to the frame angle of 750, we can

  consider it as the frame angle of -15.

  Consequently, it follows from the description

  above it is impossible to match the factors <0, 0 <45 and 0,15 corresponding to the respective weft pitches, satisfying the correct conditions, even when

  choose m, m 5, m 15 and k from any integer.

  As a result, in practice, the integer values of mo, m 45, m 15, and k 15 are chosen so that the pixel elements of pixels 50, 545, and 515 can be similar to one another so as to obtain O <, <4, and K 15 analogues

for the frame steps.

  In fact, the pitch P is obtained by multiplying the factor i <of the frame pitch by a real length X of a side of an image element that is obtained when the element

  quantified image is recorded on a photosensitive material

ble, ie: P = p <e.

  When the degraded halftone point is quanti-

  and stored in the semiconductor memory and the halftone signals are generated, the periodicity of the

  Repetitive pattern of the halftone structure is used.

  The value of this periodicity greatly influences the capacity

city of memory.

  For example, the number of picture elements aligning during a period is expressed using the integer values mo, m 45, m 15 and k 15, when the angle of

  frame is 0, 450 or 150, as described previously

2 2

  For example, it is clear that the number of picture elements for the frame angle of 15 is much larger than the others, and

  that, as a result, the memory capacity becomes much higher than

better than others.

  Consequently, the integer value m 0 is chosen so that m 15 + k 15 is low.

2 2 5 1

  that m 15 + k corresponds to the number of pixels 515 if a too low value of the latter is determined,

  this reduces the number of density steps.

  However, the screen angles of 0, 150 and 75 are generally used for yellow, magenta and cyan plates, and the number of density or gradation steps for yellow, magenta and cyan plates can be reduced. As a result, the density bearing numbers for the frame angles of 150 and -15 are reduced compared to those required for the frame angle of 50.degree. 45, which reduces the memory capacity However, as described above, if the number of density steps varies, the number of picture elements S for different frame angles may not be neighbors, what

  prevents the similarity of the factors O <of the frames.

  The present invention relates to a method for electronically recording a halftone image, to be used in a halftone image reproduction machine for making photographs, without the aforementioned drawbacks, capable of giving approximately the effective frame pitches for different frame angles, regardless of their number of picture elements of a quantized gradient halftone dot, to prevent a halftone image from causing moire, to change the screen pitches for different frame angles without changing the sweep width and to determine the number of different picture elements per period for

  different frame angles, while retaining the ability to

city of memory.

  According to the invention, a method of

  electronic halftone image recorder for use in a halftone image reproduction machine * for taking pictures, wherein a plurality of halftone data corresponding to a plurality of picture elements a halftone point

  are extracted simultaneously from a memory in the-

  which the quantized gradient halftone dot is recorded, in synchronism with image signals, and in which the halftone data and the image signals are added to obtain recording signals and, according to the recording signals a plurality of exposure light beams are controlled to record a halftone image, characterized in that it comprises the steps of a) selecting the number of light beams included in a unit of scanning width

  in a weft pitch, and b) to control the light beams

  selected according to the recording signals.

  Other features, objects and benefits of

  the invention will emerge from the detailed description which

  FIG. 1 is a block diagram of a machine for electronic reproduction of halftone images, implementing a method according to the invention. invention; FIG. 2 is a diagram as a function of time of control pulses generated by a clock circuit of FIG. 1; Fig. 3 is a block diagram of an address counter for a frame control memory of Fig. 1; Fig. 4 is a block diagram of a shift register of Fig. 1; Fig. 5 is a block diagram of an address signal generator for a frame pattern memory of Fig. 1; Fig. 6 shows degraded halftone dots having different frame angles, which are quantized and recorded in the frame pattern memory; Fig. 7 is a halftone data memory pattern of a quantized degraded halftone dot corresponding to a frame angle of 00, recorded in the frame pattern memory; Fig. 8 is a memory diagram of a quantized degraded halftone dot corresponding to a frame angle of 450, similar to Fig. 7; Fig. 9 is a memory diagram of a quantized degraded halftone dot corresponding to a frame angle of 15, similar to Fig. 7; Figure 10 is an enlarged memory diagram

  taking up an essential part of Figure 9.

  Referring now to the accompanying drawing, the

  FIG. 1 represents an electronic reproduction machine

  half-tone images to make snapshots

  halftone, implementing a method according to the invention.

  A scanning device for recording an image comprises a motor 1, a rotating cylinder 2

  driven by the motor 1, having a peripheral surface

  3 on which is fixed a photosensitive material 4, an exposure light beam 5 projected onto the photosensitive material 4, a recording head 6 movable in the direction of the axis of the cylinder, a threaded rod 7 intended to move the recording head 6, and a

  motor 8 which drives the threaded rod 7.

  A rotational encoder 10 rotatably mounted on a rotating shaft 9 of the cylinder 2 detects the rotation of said cylinder 2. This rotary encoder 10 generates

  not only a pulse g 1 per revolution at the pre-position

  determined, but also a plurality of pulses of

  phase g 2 at intervals equal to each revolution of the cylinder 2.

  The recording head 6 delivers a row of

  exposure light beams 5 aligned in the direction

  of the cylinder axis, and each light beam 5 is controlled independently so as to take two values such as "present" and "absent". These light beams can be generated by separating a laser light beam 11 into a plurality of beams. (ten in the present

  mode of execution) of light beams L 1 to L 1 o

  the same light energy, by means of a divider of

beam 12.

  These light beams L 1 to L 1 o are sent to shutters 13 1310, respectively, and the shutters

  13 131 send light beams L 1 '-Li O', when

  they are open, with ten optical fibers 141 to 141 o, res-

  The optical fibers 141 to 14 are respectively terminated at the recording head 6, and their free ends are aligned on a row in the direction of the axis of the cylinder in the order of the light beams L 1 to L 10 opposite the

  light entry surface of a lens with a varia-

  included in the recording head 6.

  The light beams L 1 'to L 10' emanating from the free ends of the optical fibers 141 to 141 and arriving at the zoom lens 15 are focused on the photosensitive material 4 by said lens 15. The light beams L 1 'to L 10 'focused are aligned on a

  line in the direction of movement of the recording head

  only 6, in the order of their serial numbers.

  The zoom lens 15 changes the magnification of the light beams L 1 'to L 1 o', when focused on the photosensitive material 4, i.e., a beam width of the actual focused light beams of the light beams L 1 'to L 10' The focal length variation of the lens 15 is controlled by a servomotor or a motor

  pulse 16 included in the recording head 6.

  The servomotor 16 is controlled by a control signal g 4 which is generated by a frame setting circuit 17, so as to adjust the projection magnification which is set by selecting the number of light beams L 1 'to L 10 'per sweep width W corresponding to a scan line pitch or to the displacement length of the recording head 6 per revolution of the cylinder 2, according to a frame pitch P, as

will mention it later.

  On the other hand, an original (not shown) is scanned photoelectrically by an original scanner (not shown) to obtain an image signal e 1, conventionally when the reproduction factor is one (scale one). ), that is, the size of the reproduction image is identical to that of the original, the scanning width W is set to the same value as the scanning width or the scanning line pitch of the scanning device of the original, and the resolution of the reproduction image depends on the scanning width W

  of the recording scanner.

  In the present embodiment, the image signal e may be a digital image signal that originates from the original scanning device in real time or is extracted from a memory recording the digital image signals. , in synchronism with the recording scanner, The servomotor or the pulse motor 16 ruler

  the projection magnification of the varifocal lens

  in such a way that an integer N of the light beams Liq, exactly is included in the scanning width W of the recording scanning device The control of the servomotor 16 is carried out by the control signal g 4 which is obtained by calculation in a central processing unit (CPU) 18 according to the desired frame pitch determined in the frame setting device 17, the scanning width W determined previously, and the integer number n of the light beams L 1 ', frame setting device 17 outputs a control signal 93 to the motor 8, so that the motor 8 moves the recording head 6 with the desired scanning width W and a control signal 95 to a circuit

  P.L L (phase lock loop) 19, so that the cir-

  cooked P L L 19 generates a clock pulse cl of a pe-

  riode corresponding to the actual beamwidth (w = W / n) depending on the number N of output light beams L 1 'L 10' included in the scanning width W.

  The circuit P L L 19 comprises a programmable counter

  whose counting position is determined by the control signal g 5, and transforms the phase pulse 92 generated by the rotary encoder 10 into the clock pulse c 1 of a period T 1 corresponding to the position of count

  determined from the programmable counter.

  The clock pulse c 1 and the pulse g 1 correspon-

  One turn generated by the rotary encoder 10 is sent to a timer circuit 20, and the timer circuit 20 outputs control pulses t 1 to t 4 shown in FIG. 2. The timer circuit 20 also regenerates the pulse of a timer.

  turn g 1 and transforms this regenerated pulse into an impulse

  c 2 start voltage for exact positioning in synchronism

with the clock pulse cl.

  The clock pulse cl at the period T1 corresponds to

  at the distance equivalent to the actual width W of the output light beams L 1 'L 1 O O focused on the photosensitive material 4, as described above, and

  the actual beamwidth W and the period T1 corresponding to

  tooth at the X-lengths of the sides-of the picture element of the

  degraded halftone point quantified in the guidelines

  the axis of the cylinder and the periphery of the cylinder.

  A start pulse c 2 is generated at a standard position of the recording cylinder 2, which corresponds to the start end of the exposure scan of the

photosensitive material 4.

  In a frame pattern memory 21 comprising a plurality of memory blocks 211 211

  corresponding to a number N (ten in the present mode of

  cution) light beams L 1 to Lio whose presence and absence can be controlled, as described above, halftone data representing a halftone weft structure and densities of

  halftone to be converted into half-point sizes

  hue, corresponding to a plurality of scan lines

  aligned next to each other are recorded.

  The frame pattern memory 21 may consist of a solid-state ROM or RAM memory, and each of the

  memory blocks 211 211 stores the data of half

  hue for the desired frame angle, e.g.

and 75 in his address area.

  The data extracted from each of the memory blocks 211 21, o is a datum of a mota 3 ent the number of bits

  desired, corresponding to a density of the half point

  degraded hue, which determines a dimension of configura-

  Halftone Points or Halftone Points The data extracted from memory blocks

  211 to 211 o are sent to a corresponding number of compa-

  221 to 221, respectively, which make up a selection of

configurator 22.

  Each of the comparators 221 to 2210 compares the image signal e 1 which enters it with the corresponding incoming data of the corresponding memory block 211 to 2110, and sends a two-valued signal to multiplexers 231 to 231 which make up a signal circuit. multiplexing 23 Multiplexers 23 to 2310 send signals to a corresponding number

  shutter control stages 24 to 241 c, respectively

  in order to fulfill the opening orders-

  closing shutters 131 to 1310, to thereby control

  selectively the light beams L 1 to L 10.

  An address selector circuit 25 includes selectors 251 to 251 each having two input channels.

  corresponding to the memory blocks 211 to 21 o The selections

  25 to 251 choose one of the two address signals.

  they receive to send the chosen address signals to the corresponding memory blocks 211 to 211 IQ,

  to address the memory blocks 211 to 2 10.

  The two address signals to be sent to the selectors 251 to 251 are generated by a first address counter Y 1 and a second address counter Y 2 which make up the address signal generator 26 The two address counters Y 1 and Y 2 are initially preset (initialized) just after the appearance of the start pulse c 2, so that their counting positions can have the same value.

desired difference.

  The address selector circuit 25, the address signal generator 26, the frame pattern memory 21 and the multiplexer circuit 23 are controlled at each occurrence of the start pulse c 2 by their predetermined control factors. according to

  desired halftone structure, and the corresponding data

  these control factors are stored in a frame control memory 27, as will be described in FIG.

detail in the following.

  In the frame control memory 27, control data words for the control factors of the elements 23, 25 and 26 are serially recorded at an address in the desired order as a frame control data word. frame control data it

  which is 16 bytes long is divided into 16 corresponding parts.

  each one byte (8 bits), and it can be extracted

  from the control memory 27 bytes per byte by addressing.

  The frame control data word which is read bit by bit is sent to a shift register 28 bit by bit, consecutively. When all the frame control data is extracted from the memory 27, the words of the control data control factors of the elements 23, 25 and 26 are recorded in the positions

  desired from the shift register 28.

  The shift register 28 comprises 16 registers each comprising 8 flip-flop circuits, as shown in FIG. 4, and the word of the frame control data leaves the shift register 28, byte byte

  (8 bits by 8 bits), aligned in parallel, of

  both between the two adjacent registers byte byte.

  The rows of the output bits of the shift register 28

  are connected to control terminals of the multi-circuit

  plexing 23, the address selector circuit 25 and the gen-

  address data 26, and the control data is sent to it as control factors for these

  elements 23, 25 and 26, by the lines of the output bits.

  The address control of the frame control memory 27 is performed by the first and second address counters 29 and 30. The first address counter 29 addresses an address for the unique word of the frame control data, and the second address counter 30 addresses an address for the one-byte division of the control data

frame.

  The second address counter 30 counts the impulses

  control stations t 2, and addresses each byte by the value

  counted f The control pulse t 2 is generated in pre-

  raising 16 clock pulses ci in synchronism with the im-

  start pulse c 2, just after its occurrence On this occasion, the control pulse t 1 which is obtained during the output of the control pulse t 2, allows the frame control memory 27 to be in state The control pulse t 2 is also sent to the shift register 28, and it stores the 8-bit information extracted from the frame control memory 27 in the shift register 28, in synchronism with the reading of the frame control memory 27, while shifting the recorded data to the positions of the frames

  lower order bits one by one.

  The first address counter 29 comprises four line counters 310, 3145, 3115 and 3175 for the frame angles of O, 450, 150 and 75, as shown in FIG.

  3 The four line counters have the same structure

  and therefore only one of them, counter 310, has been shown in detail in FIG.

  310 comprises a counter 32 and a comparator 33 which

  This base counter m counts the start pulses c 2, and the counting position of the counter 32 circulates in such a way that a value

  comparator m O of the comparator 33 is a limit value.

  The comparison values mo, m 45, m 15 and m 75

  line meters 310, 3145 and 3115 and 3175 are prede-

  mined according to the half-tone pattern period

  repetitive, as will be described later, and they

  come from the adjusting device 34.

  The frame control data to be recorded in the frame control memory 27 is allocated to divided address areas for each frame angle of 0, 450, 15 or 75, and the first addresses of the address areas are given. as offset values

  X 0, X 45, X 15 and X 75 corresponding to the remaining frame angles

  points of 00, 45, 15 and 75 These offset values

  X 0, X 45, X 15 and X 75 are set up in a control device.

  setting of numbers for each frame angle position.

  When the desired framing angle is chosen, the corresponding offset value among X 0, X 45, X 15 and X 75 and one of the counting positions D D 45, D 15 and D 75 of the line meters 31 O 3145 e 315 and 3175 selected by a cooperating selector 36 are fed to an adder 37. The adder 37 adds the output value D of the line counter 310, 3145 e 3115 or 3175 and the offset value X of the setting 35, and sends the addition value D + X to the frame control memory 27, so that an address corresponding to the data word

  frame control is addressed to it.

  The frame control data sent to the register

  offset 28 at the start end of the scanning

  registration in the direction of the periphery of the cylinder

  by means of the start pulse c 2 are retained during

  recording sweep, and they control the generation of the halftone dot pattern of

  the recording scan area.

  As shown in FIG. 4, in the shift register 28 storing the word of the frame control data, the end of the transfer direction of the shift register 28 being the least significant bit, the data corresponding to the 40 bits of FIG. lower weight, to the next 8 bits, to the next 55 bits of higher weight and

  the upper 10 bits, are sent to the multi-circuit

  tiplexage 23, at shutter control stages 24 in the form of marking codes, at the signal generator

  address 26 and the address selector circuit 25, respec-

  The remaining 15 bits of higher weight are not

not used.

  The 40 bits joining the multiplexing circuit 23 are subdivided into 10 words of control codes M 1 to M 1 o of four bits each, starting from the position of the least significant weight. The 10 words of the control codes M 1 to M 1 o are sent to the multiplexers 231 to 2310, respectively, and the binary codes of the control codes M 1 to M 10 can each express one of the numbers 1 to 10 independently,

  choose the outputs of the comparators 221 to 2210 corre-

laying down to the numbers expressed.

  Each of the 4-bit control codes M 1 to M 10 can express 16 code numbers, i.e., six other numbers out of 1 to 10, which do not match comparators 221 to 2210 using one other numbers of the codes, outside 1 to 10, the multiplexers 231 to 231 can be controlled by choosing the other input signal devices, instead of the configuration selector 22, which makes it possible to control the presence or the absence of the light beams Li at L 1 U, at the same time, independently of the

frame configuration.

  The next 8 upper bits are used in the form of two 4-bit mark-start and end-of-marking codewords KS and KE to record marks such as ticks in the start positions of

sweep and end sweep.

  The upper 10 bits joining the separate circuit

  address reader 25 are divided into ten words of selection codes of a bit SE 1 to SE 10 from the position of lower weight The ten selection codes SE 1 to SE 1 O are

  sent to the corresponding selectors 251 to 251, respectively

  and choose one of the outputs of the first address counter Y 1 and the second address counter Y 2

  of the address signal generator 26.

  FIG. 5 shows a mode of execution

  the address signal generator 26, and the 55 bits joining the address signal generator 26 are subdivided into 5 11-bit code words from the lowest position, such as an offset code Y 10 for the address counter Y 1, a shift code Y 20 for the address counter Y 2, an initialization code

  Y 1 I for the address counter Y 1, and an initialization code

  Y 2 I for the Y 2 address counter, and a code of

  YS traffic factor for the frame data.

  The offset codes Y 10 and Y 20 to be sent to the first

  first Y 1 address counter and the second address counter.

  its Y 2, respectively, express the initial addresses of the address areas for the frame angles such as O, 450, 150 and 750 in each of the memory blocks 211 to 21 as offset values, because the halftone data corresponding to the different frame angles

  are stored in the respective address areas cor-

  corresponding to the frame angles in each block of memory.

  The offset codes Y 10 and Y 20 are sent to the summaries

  39 Y 1 and 39 Y 2, respectively, where they are added to the counting positions that are obtained by counting the clock pulses ci in the respective counters 38 Y 1 and 38 Y 2 and are also sent to the adders

respective 39 Y 1 and 39 Y 2.

  The initialization codes Y 1 I and Y 21 correspond to the offsets of the addresses, so that the halftone data of the discontinuous address numbers, stored in each memory block 211, or 211 o can be aligned on a line in the direction of the periphery of the cylinder by shifting the addresses of some halftone data The initialization codes Y 1 i and Y 2 I are fed into the respective counters 38 Y 1 and 38 Y 2 by the control pulse t 3 which is generated as a result of

  the control pulse t 1, as shown in Figure 2.

  The traffic code factor YS is given for frame angles of 0, 450, 150 or 750 corresponding to the number of picture elements included in a period, according to the predetermined periodicity of the screened structure.

  YS circulation factor code is sent to comparisons

  40 Y 1 and 40 Y 2 and is compared to the count values of the

  counters 38 Y 1 and 38 Y 2, which are also sent to

  40 Y 1 and 40 Y 2, respectively Where the

  The counting counter of the counter 38 Y 1 is at least equal to the circulation factor code Y S, the counter 38 Y 1 is reset to zero by the output of the comparator 40 V 1, so that the adder 39 Y 1 circulating a address signal A 1 delivered by the first address counter Y 1 Similarly, when the counting position of the counter 38 Y 2 is at least equal to the circulation factor code YS, the counter 38 Y 2 is reset to zero by the output of the comparator 40 Y 2, so that the adder 39 Y 2 circulating a signal

  address A 2 issued by the second address counter Y 2.

  The counters 38 Y 1 and 38 Y 2 are also reset to zero by the start pulse c 2 On this occasion, the start of the start of counting of the counters 38 Y 1 and 38 Y 2 is controlled by the control pulse t 3, shown in FIG. 2, thus delivering the Y 1 O + Y 1 I and Y 20 + Y 21 addition values to the offset values Y 1 O and Y 20 and the initialization values Y 1 I and Y 21 as initial values of the address signals A 1 and A 2 at the time of

this startup.

  Thus, one of the address signals A 1 and A 2 obtained is chosen by the address selector circuit 25 to control the memory blocks 211 to 211 of the memory of

frame configurations 21.

  We will now describe the information of half

  hue saved in the memory blocks.

* Figure 6 shows half-life points

  degraded hue with the frame angles of O, 450 and 150, which are quantized and stored in the memory

frame configurations 21.

  A square ABCD denotes a zone of half-points

  degraded hue or a unit area of half points

  shade, e means a real length on one side of a

  Image, SO, 545 and 515 designate the numbers of

  image areas included in the unit areas of the screen angles of O Q, 45 and 150, and PO, P 45 and P 15 denote the

  not unitary areas of halftone dots.

  Each frame pitch Po, P 45 or P 15 is proportional to the square root of the number of picture elements SO, 545 or 515. Therefore, in the unit areas of halftone dots having the frame angles of O, 450 and shown in FIG. 6, the numbers of picture elements SO, 545 and

  515 are respectively 169, 200 and 130, different numbers

  and when the length of the pixel side is determined to be the same, their weft pitches p O, p 45 and P 15 are different. With respect to the screen angle of 750, it is symmetrical with the frame angle of

    and, as a result, it is very easy to grasp.

so no explanation.

  FIG. 7 shows a memory diagram of the halftone data of the degraded halftone dot

  quantified by a frame angle of 0 O, represented on the

  6a, which is stored in the memory blocks 211 to 2110 of the frame pattern memory 21, A plurality of halftone data columns are divided by the minimum repeat unit of the halftone frame. , and they are stored in the address areas corresponding to the frame angle of 0 of the memory blocks 211 to 211 o corresponding to the numbers

of columns.

  For example the 13 picture elements including the one comprising

  point A of the first column shall be recorded consecutively

  in the address area for the frame angle of

  O O of the first memory block 211 from the element of i-

  mage comprising point A in the order of the address numbers

  his Then, columns two to ten picture elements,

  parallel to the first column, are recorded

  in the second, tenth memory blocks 212 to 211, respectively and continuously, in the same manner as the first column, which stores the first group of picture elements comprising the ten columns of the picture elements with the same addresses in the blocks

from memory 211 to 211 o.

  In this case, there are only ten blocks of memory and,

  as a result, columns eleven to thirteen of half

  tint of the unit area of halftone dots ABCD are

  always necessary So, assuming that a single zone

  of additional halftone dots ABCD placed next to the ABCD area described above at a distance, ten columns of halftone data, the

  eleventh being placed in the first rank corresponding to the first

  first block of memory 211, are stored in the blocks of

  memory 21 h to 2 10 in the same way as in the description

  above, so that the second group of picture elements comprising the ten columns of picture elements with the same addresses is stored in the memory blocks

211 to 210.

  In each memory block 211, or 2 10, two groups of halftone data, aligned in a column at a distance from each other, are consecutively stored by addressing from the first initial address and the second These two initial addresses, the first and the second, correspond to the offset codes

  Y 10 and Y 20 to give the address counters Y 1 and Y 2, respectively

  The number (13, in the present embodiment) of the picture elements of a group, continuously aligned in a column, corresponds to the circulation factor code YSO *. A diagram is shown in FIG. of memory of the halftone data of the quantized degraded halftone point having a frame angle of 45, as shown in FIG. 6b, in the memory blocks

  211 to 21 11 of the frame pattern memory 21.

  When the frame angle is not O, the sides

  of the unit area of halftone dots ABCD does not extend

  not parallel to the directions of the periphery of the cylinder and the axis of the cylinder, and consequently, we assume a square EFGH circumscribed to the unit area of points of

  halftone ABCD, whose four sides extend parallel

  to the directions of the periphery of the cylinder and the axis of the cylinder, quantified in the image elements, which leads to the quantification of the unit area of points

  of halftone inscribed in a mosaic pattern.

  This circumscribed square EFGH includes half-time data

  more than twice the number of halftone

  grade or the unit area of halftone dots, and four

  triangles Q 1, Q 2, Q 3 and Q 4 which are obtained by making a parti-

  the inscribed square ABCD by its diagonals N and BE, are in

  relationship with four triangles Q 1, Q 21 Q 3 and Q 4 obtained by

  the circumscribed square EFGH by the four sides of the inscribed square ABCD and are positioned at its four vertices, so that the first four triangles can be superimposed on the last four by transferring the first ones in parallel

the directions of the raster lines.

  A plurality of columns of halftone data aligned in the direction of the periphery of the cylinder are

  subsivised by 20 pixels of the repetition period.

  which are included in one side of the square EFGH circumscribed

  10 columns of the first half of the halftone square-wave data EFGH, each column comprising 20 halftone data, are recorded in the address areas corresponding to the frame angle of 45 of the memory blocks 211 to 2110 as first group of halftone data, in the order of the column numbers, by addressing from the first address of the address areas Then, ten columns of the second half of halftone data of the square circumscribed EFGH are stored in the memory blocks 211 to 211 o, as the second group of halftone data, by addressing from the second initial address of the address areas,

  in the same way as the first half of half

shade described above.

  The first initial address and the second initial address of the first group and the second group of halftone data correspond to the offset codes Y 1045 and Y 2045 corresponding to the frame angle of 450, and the number of elements of image aligned on a column of a

  group is the traffic factor code.

  When the frame angle is 0 and 450, because it is not extracted from halftone memory of the intermediate address of the start-up repetition period, the initialization codes Y 1 I , Y 210, Y 1145 and Y 2 14, to be sent to the address counters Y 1 and Y 2 are always set to "1", so as to address the first address. When the screen angle is 450, as shown in FIG. 6b, the halftone data corresponding to the unit area of halftone dots can be

  obtained from the first group of half-life data

  Thus, since the number of memory blocks 211 to 21 is half of the 20 picture elements included in one side of the circumscribed square EFGH, the first group

  includes all the corresponding halftone data.

  at a degraded halftone point and we can ob-

  keep the same data with the same addresses as those of the second group by shifting the initial addresses by means of the initialization codes Y 1145 and Y 2145 In this case, the initialization codes Y 1145 and y 1 are fixed to the number of elements of the image element comprising the point E to the image element comprising the point A. FIGS. 9 and 10 show a memory diagram of the half-tone data of the half-point -teinte

  quantized gradient with the frame angle of 15, indi-

  6c, stored in the memory blocks 211 to 211 of the frame configuration memory 21 On

  FIG. 9 shows ten columns of half-wave data.

  tint of a minimum repetition period in the direction

  columns, and there is shown in FIG.

  essential part on an enlarged scale.

  In this embodiment, shown in FIG. 6c, an EFGH square circumscribes the degraded halftone dot area ABCD, as well as in the execution mode.

  corresponding to the frame angle of 450, described above.

  Then the circumscribed square EFGH is quantified by the

  image, which quantifies the inscribed square ABCD in one

  mosaïque configuration, in the same way as the mode of

  corresponding to the frame angle of 45 O.

  In this case, the four sides of the circumstantial square

  written EFGH are divided into a ratio m: k equal to 11: 3 by the four vertices A, B, C and D of the unit area of halftone dots inscribed ABCD, and this ratio corresponds to tg 9 = k, ok and m are integers, which determines m

the frame angle 9.

  The minimum repetition unit of the quantized raster structure having angle θ whose tangent is tg C = k / m, comprises a number m 2 + k 2 of picture elements in the rows and columns directions, respectively. In this embodiment, the circumscribed square EFGH comprises a number of 14 picture elements in the row and column directions, respectively, and

  the value of the number m 2 + k 2 on the side of the square repeating pattern

minimum age is 112 + 32 = 130.

  The first ten columns of the halftone data each comprising 130 picture elements in the direction of the periphery of the cylinder, the minimum repeat pattern of the quantized halftone structure comprising a number of (m 2 + k 2) 2 picture elements are recorded in the address areas corresponding to the screen angle of 150 memory blocks 211 to 21 o, as the first group of halftone data, in the order of the numbers of column pir addressing, in the same way as for the execution mode

  described above, corresponding to the frame angle of 45.

  In this embodiment corresponding to the frame angle of 150, the remaining groups of halftone data (from the eleventh to the thirtieth column of halftone data) of the minimum repetition pattern of the halftone structure quantized in the

  memory blocks 21 to 2110, which prevents the zones from

its to increase.

  The remaining columns, from the eleventh to the thirtieth, halftone data, can be obtained

as follows.

  In blocks of memory 211 to 211 where I

  first columns of halftone data are stored with the addresses 1 to 130 in the column direction and, when the address signals are put into circulation, the first line of ten halftone data follows the

    line of ten halftone data.

  The first line (columns eleven to twenty) of the second

  halftone data group of the repeating pattern

  of the quantized halftone structure is stored

  at the address 51 of the first half data group

  hue stored in memory blocks 211 to 211 o,

  as shown clearly in Figure 10.

  Therefore, the second group of halftone data can be obtained by extracting the halftone data recorded in the memory blocks 211 to 211 by addressing the address to the address 500, while the addresses are circulating. This address is implemented by sending the address number 51 to the address counters Y 1 and Y 2 as the initialization codes Y 15 and Y 2 115. The remaining groups three to thirteen of halftone data can be

  obtained in the manner described above.

  The address areas corresponding to the frame angle of 150 in the memory blocks 211 to 211 are chosen by the Y 15 and Y 2015 offset codes which express the initial addresses of the address areas corresponding to the frame angle of 150 The YS circulation factor code is set to

as Qfn has described above.

  In blocks of memory 211 to 2110 recording the

  half-tone data described above, the decalcification codes

  the address areas for the different frame angles, and the initialization codes address the first picture elements extracted from the memory blocks in the mode.

of circulation.

  Offset codes can be used for

  the first group and the second group of half

  tint separately, as well as to change the address areas

  for the different frame angles.

  For example, when the screen angle is 00, as shown in Fig. 7, in the case of ten light beams

  output, the picture elements of the first group are

  in the first scanning section No. 110 and those of the

  cond group are addressed in the second scanning section n 21 V in the order of memory blocks 211 to 2111 In this

  case, the order of alignment of the picture elements in the direc-

  The lines corresponding to the output light beams L 1 to Llo-0 However, in the third scan section 310 8 to 10 columns of the first group and 1 to 7 columns

  the second group should be addressed to obtain the co-

  8 to 13 and columns 1 to 4 of halftone data.

  In this case, the shift code Y 1 QO for addressing the initial address of the first group is transmitted to the address counter Y 1 and the address offset code Y 200 for addressing the initial address of the second group is given to the address counter

  Y 2 The selector codes SE 8 to SE 10 to be sent to the selec-

  258 to 25 are determined so that the address signal A 1 output from the address counter Y 1 is sent to the memory blocks 218 to 2110, and the selector codes SE 1 to SE 7 to be sent to the selector 251 to 257 are determined so that the address signal A 2 coming out of the address counter Y 2 is sent to the memory blocks

211 to 2110

  In this case, however, the data line of

  halftone extracted from the memory blocks 211 to 2110 does not cor-

  do not respond to light beams L 1 to L 10, and to

  arranging the order of the data extracted from the memory blocks 211 to 2110, the control codes M 1 to M 10 to be sent to the multiplexers 231 to 2310 are determined so that the multiplexers 231 to 2310 select the outputs of the comparators 228, 229 , 2210, 221, 222, and 227, respectively, which puts the outputs of the memory blocks 211 to 2110 in connection with the light beams L 1 to L 10, in the order

longed for.

  This control of the connection between the comparators 221 to 2210 and the multiplexers 231 to 231 can be made, as appropriate, when the frame angle is changed to other

  values, such as 45, 15 and -15.

  When recording is performed using ten light beams for all frame angles, as shown in Figure 6, the weft pitches are different for each frame.

each frame angle.

  The variation of the frame pitch P of the halftone structure for the different frame angles according to the number of picture elements S of the halftone structure,

  the scanning width W and the numbers N of light beams

  In the scanning width W, it is obtained according to formula (1) below, and the result is shown in the following table:

P = W (1)

  n Angle of k / m S F / frame step factor: f / n frame ___n = l n = 2 n = 3n = 4 n = 5 n = 6n = 7 n = 8n = 9 n = 10

  (O 0/13 169 13 13 6.50 4.33 3.2512.60 2.17 1.86 1.63 1.4411.30

    10/10 200 14.1 14.1 7.07 4.71 3.543.23 2.36 2.02 1.77 1.57: 1.41

  + 15 3/11 130 11,4 11,4,5,70 3,80 2,85 i 2,28 1,90 1,63 1,43 1,2711,14 _ _ _ _ _ It is clear that by varying the number N of light beams, it is possible to adjust the pitch of the wefts for different

  weft angles, so that they are approximate values

  mative, and we can vary the weft steps while keeping them at approximate values. For example, when nine, ten and eight light beams are used for frame angles of O, 450 and + 150, respectively, we obtain as frame pitch for the frame angles of O, 450, 150 and 750 Po = 1.44 W, P 45 = 1.41 W, P 15 = 1.43 W and P 75 = 1.43 W The other weft steps could be obtained from the numbers N of the light beams for the different angles weft whose V / n factors

  weft are approached, as on the table.

  As described above, when the number N of the light beams is varied, the number N of the picture element line extracted from the frame pattern memory 21 differs from the number N of the picture elements. image actually used, and so the periodicity in the direction of the cylinder axis varies according to the number N of

light beams used.

  For example, when the raster angle is 00, as shown in Fig. 7, in the case where N = 10 and N = 10, the semitint structure composed of unit areas of halftone dots each comprising 13 columns of picture elements is recorded-all columns and, therefore, the repetition period becomes the smallest common multiple 130 As a result, since 130 picture elements are extracted every 10 numbers by 10 light beams, the first condition returns after 13 repetitions. This means that after the scanning section NO 131, the same scanning section appears as the first scanning section NO 110, which means

  that it takes 13 words of frame control data to

  blur the corresponding relation between the arrangement of picture elements in the direction of the cylinder axis and

the light beams Li to L 10.

  This number of repetitions corresponds to the comparison value m O established in the first address counter.

  for the frame control memory 27.

  When the number N of light beams used is 9, the least common multiple of 9 and 13 is 117 which is the number of repetitions of the picture elements, and 117/9 = 13 indicates the number of repetitions of the scans. i.e. mo = 13. This number of scan repetitions indicates the number R of picture elements included in the repetition period of the halftone structure regardless of the frame angle, and from the smallest common multiple m of the number of scan repeats R and the number N of picture elements actually used, the smallest common multiple is obtained. The m / n value corresponds to the number of words of the frame control data. Since the contents of the frame control data are modified by modifying the number N of light beams used, the frame control data is prepared according to the different frame angles O and the numbers n of the different light beams used and records them in advance in a recording medium such as a floppy disk 41, etc. This frame control data is stored in the frame control memory 27 by means of the central processing unit (CPU) 18 ,

before starting the process.

  It is clear from the description above,

  according to the present invention, the number N of output light beams L 1 to L 1 o included in the scanning width W can be determined at will, so that

  can choose the frame pitch P of the halftone picture of

  many ways, without changing the sweep width W.

  Since we can modify the free frame pitch P

  Without changing the scanning width W which is fixed, the number of picture elements of the quantized gradient halftone points corresponding to the frame angles of O, 450, 150

  and 750, which must be stored in the semiconductor memory.

  conductors, may also be different, other than approximate numbers similar to the same numbers, and therefore the selectivity of the pixels included in the degraded halftone dot to be quantized may be

greatly increased.

  In addition, since the number of picture elements included in the degraded halftone dot can be varied for each frame angle, the capacity of the semiconductor memory can be reduced by making the range reproduction densities of the black snapshot,

  different from those of polychrome clichés.

  It goes without saying that we can add to the descrip-

  previous version and the attached drawing of many

  fications of detail without departing from the scope of the invention.

Claims (2)

  1 Method of electronically recording images at   modeled to be used in a repro-   halftone image ducting for taking pictures, wherein a plurality of halftone data corresponding to a plurality of picture elements of a degraded halftone dot are simultaneously extracted from a memory point   quantized graded halftone is recorded, in synchro-   with the image signals, and in which the halftone data and the image signals are added together to   obtain recording signals, and a plurality of   exposure light beams are, according to the recording signals   recording, controlled to record a halftone image, characterized in that it comprises the steps of; a) selecting the number of light beams included in a recording scan width, as a function of a frame pitch, and b) controlling the selected light beams according to the recording signals. Method according to claim 1, characterized in that the frame angle of the degraded halftone dot is   chosen from the following values; 00, 45, 15, 75.