Image synthesizing system

An image synthesizing system provided with an interpolation circuit for interpolating data of neighboring pixels of a multi-level picture, a decompression circuit for converting data representing characters and graphic forms into data of pixels thereof, a first look-up table unit for converting the data of pixels composing the characters and graphic forms into data representing gradation levels of a four-color halftone, a second look-up table unit for outputting control data for synthesis which includes halftone-dot pattern information used to indicate halftone-dot patterns corresponding to the characters and the graphic forms and region discriminating information used to indicate which of the characters and the graphic forms should be clipped, a multi-level picture and bi-level element comparison circuits, which are independent of each other, respectively converting the multi-level picture and the bi-level characters and graphic forms into bi-level dot patterns and a selecting circuit for selectively outputting one of the bi-level dot patterns respectively corresponding to the bi-level characters and the bi-level graphic forms.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention generally relates to an image processing system and more 
particularly to an image synthesizing system for electronically 
synthesizing data representing an image from data representing bi-level 
characters, graphic forms and ground tints and data representing 
multi-level pictures such as photographs, which are inputted from a layout 
scanner of a computerized typesetting system (hereunder referred to simply 
as a CTS scanner) or what is called a multi-level picture scanner. 
Generally, bi-level characters and graphic forms such as illustrations and 
continuous-tone photographs and pictures mingle in printed matter (e.g., 
news papers and magazines). An image synthesizing system is used to obtain 
bi-level pictures from such halftone photographs and pictures and print 
the thus obtained bi-level pictures. 
2. Description of The Related Art 
There have been two kinds of conventional methods for synthesizing an image 
by inserting bi-level characters and graphic forms in a multi-level 
photograph or picture. In case of a first conventional method, bi-level 
characters and graphic forms to be inserted are cut out of a picture. 
Subsequently, the characters and the graphic forms are pasted up on the 
multi-level photograph. Finally, data representing a synthesized picture 
is obtained by performing a scan of the photograph by using a scanner. In 
contrast with this, in case of the other conventional method (hereunder 
referred to as a second conventional method), bi-level characters and 
graphic forms to be inserted and a multi-level photograph are first 
digitized separately from one another. Then, a synthesized picture is 
obtained by synthesizing or editing data representing the bi-level 
characters and graphic forms and data representing the multi-level 
photograph by using a computer. 
The first conventional method was employed in, for example, a sporting 
newspaper company. In an office of the sporting newspaper company, many 
staffs cut headings, graphic forms and photographs or the like out of 
materials and effected a synthesizing or editing thereof. The first 
conventional method, however, has a drawback that other pictures, 
characters and graphic forms need preparing each time the size of a 
synthesized picture is changed (namely, each time the magnification or 
contraction of a picture to be obtained is required. To eliminate this 
drawback of the first conventional method, it has been desired to perform 
the synthesizing operation at a high speed and save labour by introducing 
a computer into an office. As a result of this, a system employing the 
second conventional method has come into use. 
Incidentally, in case of the first conventional method, the bi-level 
characters and graphic forms thus inserted are not read as binary data but 
read as multi-level image data. Therefore, a part of a multi-level 
photograph or picture may be cut out and pasted up on another multi-level 
photograph. 
In contrast, in case of the second conventional method, a photograph or 
picture and characters and graphic forms are electronically digitized by a 
color scanner. Then, only a necessary part of digital data obtained by the 
color scanner is extracted by using a man-machine interface. Further, a 
synthesizing/editing of a picture is performed by processing the digital 
data. Final results of the synthesizing/editing are converted into data 
representing an image composed of bi-level dots (hereunder referred to as 
binary halftone-dot data). A recording or printing of the synthesized 
picture is then effected in accordance with the binary halftone-dot data. 
Incidentally, binary data representing characters and graphic forms, which 
are digitized by an existent CTS scanner and are preliminarily converted 
into data representing portions each consisting of uniformly distributed 
dots of the same size (hereinafter referred to as screen-tint data), and 
binary picture data other than simple binary data may be employed as data 
representing characters and graphic forms. Examples of systems for 
converting data representing characters and graphic forms into screen-tint 
data are disclosed in Japanese Patent Application Provisional Publication 
Nos. 1-105743 and 1-13587 Official Gazettes. These systems, however, 
cannot insert bi-level characters and graphic forms into a multi-level 
picture. 
Further, in case where the synthesized picture is recorded or printed as 
bi-level picture by performing the second conventional method, the 
multi-level photograph or picture is first converted into a bi-level 
image. Then, the thus obtained bi-level image and the bi-level characters 
and graphic forms are synthesized by executing a software program. 
Thus, it is necessary for the conventional systems to temporarily store the 
data representing the multi-level photograph or picture, the binary 
halftone-dot data representing the result of the conversion of the data 
representing the multi-level photograph or picture thereinto, the data 
representing the bi-level characters and graphic forms to be inserted and 
sometimes the data obtained as the result of the synthesizing of the 
multi-level photograph and the bi-level characters and graphic forms. 
Therefore, an auxiliary storage having large storage capacity such as a 
magnetic disk is required. Moreover, in case where the sizes of the 
photograph, picture, characters and graphic forms of which data have been 
once read are changed, it is necessary to obtain data representing the 
photograph, picture, characters and graphic forms of which the sizes are 
increased or reduced. This takes much processing time in case where this 
processing is performed by executing the software program. Additionally, 
every change of the sizes of the photograph, picture, characters and 
graphic forms, it is necessary to perform the synthesizing/editing 
processing over again. The present invention is created to resolve these 
problems of the conventional system. 
It is accordingly an object of the present invention to an image 
synthesizing system which can reduce storage capacity of an auxiliary 
storage such as a magnetic disk, can perform the functions of regulating 
the size of a synthesized image by effecting interpolation, expansion and 
contraction of a multi-level photograph or picture, of arbitrarily 
coloring and changing the colors of bi-level characters or graphic forms, 
of converting the multi-level photograph or picture and the bi-level 
characters and graphic forms into bi-level halftone-dot photograph (or 
picture), characters and graphic forms independently from one another, of 
arbitrarily indicating the number of halftone lines (hereunder referred to 
as a halftone line number) and a halftone-dot angle correspond to each 
region of the characters and graphic forms, of extracting arbitrary 
regions of the characters and graphic forms and synthesizing the extracted 
regions of the characters, the graphic forms and the multi-level 
photograph or picture and of outputting data representing a resultant 
synthesized image consisting of bi-level dots and can perform each 
processing at a high speed by implementing firmware. 
SUMMARY OF THE INVENTION 
To achieve the foregoing object and in accordance with the present 
invention, there is provided an image synthesizing system which comprises 
an interpolation circuit for interpolating data of neighboring pixels of a 
multi-level picture, a decompression circuit for converting data 
representing characters and graphic forms into data of pixels thereof, a 
first look-up table means for converting the data of pixels composing the 
characters and graphic forms into data representing gray levels (namely, 
gradation levels) of a four-color halftone (hereunder referred to as 
gradation level data), a second look-up table means for outputting control 
data for synthesis which includes two kinds of information (namely, 
halftone-dot pattern information used to indicate halftone-dot patterns 
corresponding to the characters and the graphic forms and region 
discriminating information used to indicate which of the characters and 
the graphic forms should be clipped), comparison circuits, which are 
independent of each other, respectively converting the multi-level picture 
and the bi-level characters and graphic forms into bi-level dot patterns 
(hereunder referred to as a multi-level picture comparison circuit and a 
bi-level element comparison circuit, respectively) and a selecting circuit 
for selectively outputting one of the bi-level dot patterns respectively 
corresponding to the bi-level characters and the bi-level graphic forms, 
thereby achieving the extraction of the characters and graphic forms to be 
inserted and the synthesizing the multi-level photograph and the extracted 
characters and graphic forms. 
Namely, in the image synthesizing system provided with the above described 
configuration, the multi-level picture is first expanded to a desired size 
thereof by effecting the interpolation of data of neighboring pixels 
thereof in a primary and subordinate scanning directions by using the 
interpolation circuit. Then, in the decompression circuit, the data 
representing the characters and graphic forms, which is compressed by 
performing a run-length encoding method and is inputted thereto, is 
converted into data representing a sequence of region discriminating codes 
respectively corresponding to pixels. Next, the data representing the 
region discriminating codes is inputted to the first look-up table means 
and is further converted into gradation level data. Then, the control data 
including the halftone-dot pattern information and the region 
discriminating information is outputted from the second look-up table 
means. Subsequently, the multi-level picture comparison circuit inputs 
various halftone-dot pattern data from a memory storing halftone-dot 
patterns corresponding to the multi-level photograph or picture and data 
representing the result of the interpolation from the interpolation 
circuit and compares each of the inputted halftone-dot patterns with the 
inputted result of the interpolation. Then, the multi-level picture 
comparison circuit outputs data representing bi-level dot pattern data 
which corresponds to the multi-level photograph or picture. On the other 
hand, and the bi-level element comparison circuit inputs various 
halftone-dot pattern data from a memory storing halftone-dot patterns 
corresponding to the bi-level characters and graphic forms and the 
gradation level data and compares each of the inputted halftone-dot 
patterns with the gradation level data. Then, the bi-level element 
comparison circuit outputs data representing bi-level dot pattern data 
which corresponds to the bi-level characters and graphic forms. 
Thereafter, the selecting circuit inputs these two kinds of bi-level dot 
pattern data and selects one kind of the bi-level dot pattern data 
therefrom in accordance with the region discriminating information read 
from the second look-up table means. 
Thus, the image synthesizing system according to the present invention does 
not need an auxiliary storage having large storage capacity such as a 
large capacity magnetic disk. Moreover, the image synthesizing system of 
the present invention can adjust the size of a photograph or picture to 
desired dimensions at a high speed by effecting interpolation, expansion 
and contraction of a photograph or picture by using firmware. Further, as 
described above, the image synthesizing system of the present invention is 
provided with two comparison circuits which are independent of each other 
and can obtain bi-level dot patterns corresponding to a multi-level 
photograph or picture and a bi-level character or graphic form, 
respectively, by using halftone-dot patterns different in halftone-dot 
angle and in halftone line number from each other. Furthermore, the image 
synthesizing system of the present invention can optionally color or 
change the colors of regions of characters and graphic forms inserted in a 
multi-level photograph or picture. Consequently, the extraction of one or 
more arbitrary pixels of characters and graphic forms, as well as the 
synthesizing of the extracted pixels of the characters and graphic forms 
and a multi-level photograph, can be performed at a high speed by using 
the firmware. Incidentally, even in case where halftone-dot patterns of 
bi-level characters and graphic forms are extracted and inserted into a 
multi-level photograph or picture, the synthesis of the halftone-dot 
patterns can be performed in the same manner.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Hereinafter, a preferred embodiment of the present invention will be 
described in detail by referring to the accompanying drawings. 
Referring first to FIG. 1, there is illustrated the construction of an 
image synthesizing system embodying the present invention. In FIG. 1, 
reference numeral 101 designates a microcomputer; 102 a direct memory 
access (DMA) controller; 103 an interface with a general purpose interface 
bus (hereunder referred to as a GIPB interface); 104 a block buffer memory 
for storing data representing a multi-level photograph or picture; 105 a 
block buffer for storing data representing data representing bi-level 
characters and graphic forms; 106 a line interpolation circuit for 
effecting an interpolation in a subordinate scanning direction; 107 a 
pixel interpolation circuit for effecting an interpolation in a primary 
scanning direction; 110 a decompression circuit for restoring data 
representing characters and graphic forms; 111 a first look-up table 
(hereunder sometimes referred to as a color look-up table) unit for 
storing gradation levels of a four-color halftone; 112 a second look-up 
table unit to be used for synthesizing image data; 115 a line buffer; 116 
a block line buffer; 118 a multi-level picture comparison circuit for 
generating bi-level dot pattern data which corresponds to the multi-level 
photograph or picture; 119 a halftone-dot pattern memory for storing 
halftone dot patterns corresponding to a multi-level photograph or 
picture; 120 a bi-level element comparison circuit for generating bi-level 
dot pattern data which corresponds to characters and graphic forms to be 
inserted to the multi-level photograph or picture; 121 a halftone-dot 
pattern memory for storing halftone dot patterns corresponding to the 
character and graphic forms; 122 a selecting circuit for selectively 
outputting bi-level dot pattern data corresponding to the multi-level 
photograph or picture, characters and graphic forms; 123 a eight-bit 
packing circuit; and 124 a output block buffer. 
Next, an operation of the image synthesizing system having the construction 
of FIG. 1 will be described in detail along data flow hereinbelow by 
referring to FIGS. 2 to 19. 
First, a block of picture data representing a multi-level picture, which is 
inputted from an external circuit, are stored in the block buffer memory 
104 through the GPIB interface 103 and the DMA controller 102 under the 
control of the microcomputer 101. On the other hand, a block of data 
representing characters and graphic forms to be inserted in the 
multi-level picture are stored in the block buffer memory 105 through a 
similar path. The data stored in the block buffer memories 104 and 105 are 
read therefrom in succession to be used in processing. Whenever another 
block of the data become necessary for the processing, this fact is 
notified to the microcomputer 101 which then causes the necessary block of 
the data to be inputted to the block buffer memory 104 or 105. 
The picture data of two lines read in succession from the block buffer 104 
are first inputted to the line interpolation circuit 106 for effecting an 
interpolation in a subordinate scanning direction (namely, the Y-direction 
or vertical direction of the multi-level picture). Then, the 
interpolation, expansion or contraction operations are effected in the 
line interpolation circuit 106. Subsequently, the data obtained in the 
line interpolation circuit 106 by effecting the interpolation is inputted 
to the pixel interpolation circuit 107 for effecting an interpolation in a 
primary scanning (X) direction (namely, in the horizontal direction of the 
multi-level picture). Then, an interpolation in the X-direction is 
performed in the pixel interpolation circuit 107 to obtain a new pixel 
having an intermediate gray level between each pair of adjacent pixels of 
the inputted block. Incidentally, the interpolation effected in each of 
the X and Y directions is linear interpolation. Further, a thinning-out 
table necessary for the interpolation effected in each of the X and Y 
directions is preliminarily generated in accordance with an interpolation 
magnification or contraction ratio and is established in an interpolation 
map memory 108 or 109. 
To effect the linear interpolation, interpolation data corresponding to 
each pair of adjacent pixels arranged on a line or adjacent pixels 
respectively placed at corresponding positions of two adjoining lines of 
the picture is preliminarily set in the interpolation map memory 108 or 
109 by using a fixed magnification ratio (e.g., 32 in this embodiment) in 
case of each of the primary and subordinate scans. When performing the 
interpolation, an interpolation increment corresponding to adjoining 
pixels of each pair is read from the thinning-out table by referring 
thereto by using thinning-out table data indicating a difference between 
gradation levels of the adjoining pixels of each pair and sampling 
positions as addresses to be read, and data of a new pixel to be inserted 
to the adjoining pixels of each pair is calculated by adding the read 
interpolation increment to original data of the pixels. The further 
details of this interpolation is described in the Japanese Patent 
Application Provisional Publication No. 1-80168 Official Gazette. For 
example, in case that the fixed magnification ratio is 32 and the 
interpolation magnification ratio is 5/3, the thinning-out table data ik 
are determined correspondingly to a parameter k indicating the order of 
output data and repeatedly having values of 0, 1, 2, 3 and 4 in this order 
and to another parameter .epsilon. indicating the timing of updating input 
data as follows: 
EQU k=0, 1, 2, 3, 4 
EQU .epsilon.=0, 0, 1, 0, 1 
EQU ik=0, 19, 2, 26, 13. 
Incidentally, if .epsilon.=1, input data is updated prior to the 
processing. In contrast, if .epsilon.=0, input data is not updated before 
the processing. 
In this way, the interpolation processing is performed according to the 
thinning-out data and the result thereof is inputted to the multi-level 
picture comparison circuit 118. 
On the other hand, the data stored in the block buffer memory 105, which 
represent characters and graphic forms to be inserted and will be briefly 
described hereinafter, are color line art data which are in conformity 
with a standard (ANSI It8. 2-1988; [UEF01]) fixed by the American National 
Standards Institute. 
This standard (hereunder sometimes referred to as the UEF01 standard) is 
set to enable data exchange among Color Electric Prepress Systems (CEPS) 
using magnetic tapes (MT) as media. Here, the color line art data is data 
compressed by the run length encoding and represents a multicolor 
character or graphic form by using a pair of a color code which is used as 
a discriminating code for discriminating what region each pixel belongs 
to, and its run length. According to the above described standard, colors 
corresponding to color codes of from 1 to 255 can be basically employed, 
but a color corresponding to a color code of 0 cannot be employed. This 
embodiment, however, is adapted to be able to employ the color 
corresponding to the color code of 0. FIG. 2 illustrates data format 
employed for the run-length encoding according to the UEF01 standard 
extended as described above in such a manner to include a color 
corresponding to color code of 0. A line starting and terminating codes 
each having a hexadecimal value [0000] which are two bytes long are set at 
a starting and terminating ends of data of one line, respectively. 
Incidentally, in the instant specification, the notation [A] indicates 
that a numeral A is in hexadecimal representation. Further, codes 
(hereunder referred to as run-length encoding codes) of one line, which 
are obtained by effecting the run length encoding, are held in a part, 
which intervenes between the hexadecimal values [0000] at both ends of the 
data (namely, the run-length encoding codes of one line). Moreover, there 
are two types of the data format, namely, a short and long formats. In 
case of using the short data format, codes of which the run lengths range 
from 1 to 255 can be represented. However, in case of using the long data 
format, codes of which the run lengths range from 1 to 32767 can be 
represented. Incidentally, in case where a plurality of lines have the 
same data (namely, the same run-length encoding codes) as a line 
immediately prior to these lines has, a line copying code indicating the 
number of lies having the same data as shown in FIG. 2 is used. For 
instance, in case of graphic forms of which each pixel has a region 
discriminating code (namely, a color code) of 0, 1 or 2 as illustrated in 
FIG. 3, the run-length encoding is effected as illustrated in FIG. 4. In 
FIG. 5, there is shown a run-length encoding code obtained as the result 
of this run-length encoding operation. This resultant data indicating the 
graphic forms of FIG. 3 is stored in the block buffer memory 105. 
Referring next to FIG. 6, there is shown a flowchart of a program for 
restoring the region discriminating code of each pixel from the run-length 
encoding code of FIG. 5, based on the data format of FIG. 2. As 
illustrated in FIG. 6, a line starting code of data of each line (namely, 
a hexadecimal code [0000] which is two bytes in length) is first detected 
by making decisions in steps S1 and S2. Then, if it is found in step S3 
that a first byte of input data is not equal to [00], this byte is 
determined to be a color code. Further, if it is found in step S12 that 
the next byte is equal to [00], the system judges that the long data 
format is used and the next two bytes represent the run length of the 
code. In contrast, if it is found in step S12 that the next byte is not 
equal to [00], the system judges that the short data format is used and 
the next byte represents the run length of the code. Then, the color codes 
of the number which is equal to the run length are repeatedly outputted 
from the decompression circuit 110 and are stored in the line buffer 115. 
On the other hand, if it is found as a result of decisions in steps S12, 
S13 and S14 that three bytes subsequent to the first byte are equal to 
[000000], the system judges that this data represents a copy code. In this 
case, the value of the code determined in step S3 is further determined to 
be the number of lines (hereunder sometimes referred to as copy lines) 
having the same data (namely, the number of repetition) and the line 
buffer outputs the data of lines of the number of repetition in 
succession. Then, the output data are stored in the block buffer. In 
contrast, if the first byte of the input data is [00] and the next byte is 
not equal to [00], the system judges that the short data format is used 
and a value represented by the second byte of the input data is determined 
to be the run length. If each of the first and second bytes is equal to 
[00] and the number of the color codes already outputted does not reach 
the size of one line in the primary scanning direction (namely, in the 
X-direction), it is judged that the long data format is used and the 
number of the color codes already outputted is determined to be the run 
length. Further, the color codes of the color codes [00] of the number 
equal to the run length are repeatedly outputted and are stored in the 
line buffer. However, if each of the first and second bytes is equal to 
[00] and the number of the color codes already outputted reach the size of 
one line in the primary scanning (X-) direction, it is judged that the 
line terminating code is detected and the number of lines of which data 
should be copied is one. Thus, the data of one line restored by that time 
is copied onto the block buffer. The above described processing is 
performed every time run-length encoding codes or data are inputted to the 
system. Turning back to FIG. 1, the region discriminating codes (i.e., the 
color codes) of one line among the data representing the characters or 
graphic forms, which are stored in the block buffer 105 and are compressed 
by effecting the run-length encoding, are restored in the manner as 
described by referring to FIG. 6. Thereafter, the restored codes are 
inputted to the line buffer 115 through the color look-up table unit 111 
and the selecting circuit 113. Then, an output of the line buffer 115 is 
inputted to the block buffer 116. When a copy code is detected in the 
sequence of the data of lines outputted from the line buffer 115 for 
storing data of one line, the number of copy lines is inputted from the 
decompression circuit 110 to an address control circuit 117. Further, when 
a line terminating code is detected, the number of copy lines (namely, 1 
in this case) is similarly inputted to the address control circuit 117. 
Then, the address control circuit 117 repeatedly performs operations of 
reading data of one line from the line buffer 115 in accordance with the 
inputted number of the copy lines and outputting the read data to the 
block buffer 116. The copying of data from the line buffer 115 to the 
block buffer 116 and the restoration processing in the decompression 
circuit 110 are timely controlled in such a manner to be halted for a time 
when the block buffer 116 become full until some data is read from the 
buffer 116 to be used in the processing to be effected in the comparison 
circuit 120. As described previously, the color look-up table unit 111 is 
provided posterior to the decompression circuit 110 and outputs gradation 
levels of a four-color halftone, namely, one of a cyanic halftone (a C 
halftone), a magenta halftone (an M halftone), a yellow halftone (a Y 
halftone) and a black halftone (a K halftone) in accordance with the 
region discriminating codes (i.e., the color codes) outputted form the 
decompression circuit 110. Next, a selecting circuit 113 selects the 
gradation levels of the four-color halftone preliminarily indicated and 
outputs the gradation levels of the selected halftone to the selecting 
circuit 122 for selectively outputting bi-level dot pattern data 
corresponding to the multi-level photograph or picture. 
Incidentally, the color look-up table unit 111 is made up of a random 
access memory (RAM) which is readable and writable. The contents of the 
color look-up table unit are preliminarily set before the processing is 
performed. Further, a read-only memory (ROM) may be used as the color 
look-up memory 111 in case that there is no need of changing the contents 
thereof. As is seen from a memory map of FIG. 7(a), data representing 256 
gradation levels, each of which is represented by one byte, of each of the 
C, M, Y and K halftones are continuously stored in the color look-up table 
unit 111. Two high order bits of data representing a reading address 
indicate kinds of the four-color halftone (i.e., the C, M, Y and K 
halftones) and on the other hand eight low order bits thereof indicate 
gradation levels corresponding to the region discrimination codes (i.e., 
the color codes) of each pixel. FIG. 7(b) illustrates 1-byte data 
representing a gradation level of which the value ranges from 0 to 255. 
Referring next to FIG. 8(a), there is shown a memory map of the look-up 
table unit 112. As is seen from this figure, data representing 256 
gradation levels of the C, M, Y and K halftones are stored in the look-up 
table unit 112 in this order from a leading address thereof. Data 
representing each reading address of the look-up table unit 112 has the 
same structure of the data representing each reading address of the unit 
111. Namely, two high order bits of data representing a reading address 
indicate kinds of the four-color halftone (i.e., the C, M, Y and K 
halftones). However, eight low order bits thereof are used to select 
control data (hereunder referred to as synthesis control data) for 
controlling a synthesizing operation. FIG. 8(b) illustrates the structure 
of the 1-byte control data of FIG. 8(a). Four high order bits of the 
control data are used to select a desired kind of bi-level dot patterns of 
the characters and graphic forms. Lowest order bit thereof is used to 
selectively output data representing the picture or data representing the 
characters and graphic forms. Thus, in accordance with the inputted region 
discriminating code (or color code), a dot pattern is selected from 
sixteen kinds of the dot patterns #0 to #15 , and either the picture is 
selected or the characters and graphic forms are. Further, corresponding 
control data is generated. In the embodiment of FIG. 1, only data 
corresponding to the preliminarily indicated color halftone is selected by 
a selecting circuit 114 according to the synthesis control data outputted 
from the look-up table unit 112 and is outputted from the circuit 114. 
Data represented by four high order bits of the synthesis control data is 
inputted to the pattern memory 121 for storing halftone dot patterns 
corresponding to the character and graphic forms. Data represented by the 
lowest order bit of the synthesis control data is inputted to a selecting 
circuit 122. The data stored in the pattern memories 119 and 121 will be 
described later. 
As described above, the bi-level dot pattern data generated in the 
comparison circuit 118 corresponding to the photograph or picture, as well 
as the bi-level dot pattern data generated in the comparison circuit 118 
corresponding to the characters and graphic forms, is inputted to the 
selecting circuit 122. In case where selection information represented by 
the lowest order bit of the synthesis control data indicates 0, the 
bi-level dot pattern data corresponding to the photograph or picture is 
selected and outputted from the selecting circuit 122 to the eight-bit 
packing circuit 123. In contrast, in case where selection information 
represented by the lowest order bit of the synthesis control data 
indicates 1, the bi-level dot pattern data corresponding to the characters 
and graphic forms is selected and outputted from the selecting circuit 122 
to the circuit 123. In the eight-bit packing circuit 123, bi-level data 
representing the result of synthesizing the photograph or picture and the 
extracted characters and graphic forms is partitioned into groups of 
8-bits thereof. Then, a serial/parallel conversion of such 8-bit data is 
effected therein. The results of the serial/parallel conversion are 
successively stored in the output block buffer 124. If necessary, the 
8-bit packing circuit 123 can output the bi-level data representing the 
result of the synthesis in what is called a bit-serial manner. The data 
stored in the output block buffer 124 is sent to an external printing 
device such as a laser beam printer (LBP) and the resultant picture is 
printed by the printing device. 
Hereinafter, the contents of the memories 119 and 121 will be described. 
FIGS. 9(a) and 9(b) are diagrams for illustrating the contents of the 
halftone-dot pattern memory 119 for storing the halftone dot patterns 
corresponding to the multi-level photograph or picture. The halftone dot 
patterns corresponding to the multi-level photograph or picture are 
two-dimensional arrays, each of which uses a storage area of 64 K bytes, 
composed of halftone dots of 256.times.256 corresponding to the C, M, Y 
and K halftones which are stored in this order in a storage area of 256 K 
bytes of the memory 119 as illustrated in FIG. 9(a). The selected one of 
the C, M, Y and K halftones is preliminarily indicated prior to the 
processing as above described. Further, dot pattern reading address data 
shown in FIG. 9(b) includes two bits indicating binary values "00", "01", 
"10" and "11" respectively corresponding to the dot patterns of the C, M, 
Y and K halftones. FIGS. 10(a) and 10(b) are diagrams for illustrating the 
contents of the halftone-dot pattern memory 121 for storing the halftone 
dot patterns corresponding to the bi-level characters and graphic forms. 
FIG. 10(a) shows a memory map of the memory 121. Further, FIG. 10(b) shows 
the contents of dot pattern reading address data. Similarly as in case of 
the memory 119, the halftone dot patterns corresponding to the bi-level 
characters and graphic forms are two-dimensional arrays, each of which 
uses a storage area of 64 K bytes, composed of halftone dots of 
256.times.256 corresponding to the C, M, Y and K halftones which are 
stored in this order in a storage area of 256 K bytes of the memory 121, 
as shown in FIG. 10(a). Each of the 16 kinds of the dot patterns #0 to #15 
can be established to have four sub-patterns, which have the same 
arrangement of dots and are stored in a storage area of 256 K bytes of the 
memory 121 but are different in color of dots from one another, 
corresponding to the C, M, Y and K halftones, respectively. Incidentally, 
the system can work if at least one kind of the dot patterns (e.g., #0) 
having four sub-patterns is provided therein within a permitted limit of 
the storage capacity of the memory 121. Thus, it is necessary for 
selecting a sub-pattern to preliminarily indicate one of the C, M, Y and K 
halftones and one of the 16 kinds of the dot patterns (#0 to #15). 
However, one of the C, M, Y and K halftones is indicated by the lowest two 
bits of dot pattern reading address data of FIG. 10(b). Namely, the C, M, 
Y and K halftones are indicated by binary values "00", "01", "10" and "11" 
represented by the lowest two bits, respectively. Further, a value 
represented by four bits subsequent to the lowest two bits and having 
orders higher than the lowest two bits indicate one of the 16 kinds of dot 
patterns (#0 to #15). 
As stated above, it is necessary to preliminarily set various parameters 
and units (e.g., the interpolation map memories, the color look-up table 
unit, the look-up table unit for the synthesis and the dot pattern 
memories). Additionally, a processing color halftone mode, an 
interpolation on/off mode and a synthesis processing on/off mode should be 
set in a mode setting latch 135 in the form of FIG. 11. As shown in FIG. 
11, the processing color halftone mode indicating a color halftone to be 
used in the processing is represented by two bits having bit positions 4 
and 5. Further, the interpolation on/off mode indicating whether or not an 
interpolation of data representing the multi-level photograph or picture 
should be performed is represented by a bit having a bit position 0. 
Furthermore, the synthesis on/off mode indicating whether or not a 
synthesis of data representing the multi-level photograph or picture and 
data representing the characters and graphic forms should be performed is 
represented by a bit having a bit position 1. In case where the 
interpolation on/off mode is an off-mode, the interpolation is not 
effected and data read from the block buffer 104 of FIG. 1 is inputted to 
the comparison circuit 118 without being changed. On the other hand, the 
synthesis processing on/off mode is inputted to the selecting circuit 122. 
If the synthesis processing on/off mode indicates an off-mode, the 
selecting circuit 122 always selects the bi-level dot pattern data 
corresponding to the photograph or picture. As explained above, the kind 
of the color halftone indicated by the processing color halftone mode of 
FIG. 11 is inputted to the color look-up table unit 111, the selecting 
circuit 113, the table unit 112, the selecting circuit 114, the memories 
119 and 121. The thus indicated color halftone is employed. 
Next, the above described image synthesizing processing of practical 
examples of the photograph or picture and the characters and graphic forms 
will be described by referring to FIGS. 12 to 19. FIG. 12(a) shows 
halftone-dot image, which is represented by the data outputted by the 
block buffer 116 of FIG. 1 and inputted to the comparison circuit 120, of 
the multi-level photograph after the interpolation is effected. FIG. 12(b) 
shows bi-level dot image, which is represented by the data outputted by 
the block buffer 116 of FIG. 1 and inputted to the comparison circuit 120, 
of the characters and graphic forms to be inserted into the picture of 
FIG. 12(a). The data of FIG. 12(b) employs the gradation levels stored in 
and outputted from the color look-up table unit 111. In this example, the 
background is represented by the gradation level 0 (i.e., a white level) 
and the characters are represented by the gradation level 255 (i.e., a 
black level). FIGS. 13(a), 13(b), 13(c), 13(d) and 13(e) are diagrams for 
illustrating portions of the picture of FIGS. 12(a) and 12(b). FIG. 13(a) 
is a waveform chart for illustrating densities of pixels of a typical line 
a of the multi-level photograph or picture, which is shown in FIG. 12(a), 
just before converted into a bi-level dot image. FIG. 13(b) is a diagram 
for illustrating bi-level dot data of the typical line a of the 
multi-level photograph or picture of FIG. 12(a). FIG. 13(c) is an enlarged 
view of a part of the line a which is indicated by a mark * in FIG. 13(b). 
FIG. 13(d) is a diagram for illustrating a part of the bi-level dot data 
corresponding to the part of FIG. 13(c) indicated by the mark *, which is 
shown in FIG. 13(b). FIG. 13(e) is a diagram for illustrating bi-level 
data corresponding to a line b of data representing the characters and 
graphic forms, which is shown in FIG. 12(b) 
Referring next to FIGS. 14(a) and 14(b), there are shown data outputted 
from the decompression circuit 110 of FIG. 1. Further, the data represent 
the region discriminating codes (i.e., the color codes) restored by the 
decompression circuit 110 from the run-length encoding codes outputted 
from the block buffer 105. Further, FIGS. 14(a) and 14(b) show different 
example of such data. In data of FIG. 14(a), two kinds of the color codes, 
namely, color code 0 indicating the background and color code 1 indicating 
the characters are used. A coloring operation is performed according to 
these color codes 0 and 1 by using the color look-up table unit 111 of 
FIG. 1. As above described, one of the C, M, Y and K halftones is 
previously selected and the gradation levels of the selected halftone are 
already outputted therefrom. In data of FIG. 14(b), three kinds of the 
color codes, namely, the color codes 0 and 1 and color code 2 indicating 
the frames which hem the characters are used. The edition such as 
modification and conversion of the color code data of FIGS. 14(a) and 
14(b) are effected in an external work station (WS) (not shown) connected 
to the image synthesizing system of FIG. 1. 
FIG. 15(a) illustrates change in level of data representing the typical 
line a of FIG. 14(a); and FIG. 15(b) shows change in level of data 
representing the typical line b of FIG. 14(b). In case of the color data 
of FIG. 15(a), the color code changes from 0 (corresponding to the 
background) to 1 (corresponding to the characters) and further changes 
from 1 to 0 again in the direction from left to right as viewed in this 
figure. On the other hand, in case of the color data of FIG. 15(b), the 
color code changes from 0 (corresponding to the background) to 2 
(corresponding to the frames of the characters) and then changes from 2 to 
1 (corresponding to the characters) and further changes from 1 to 0 in the 
direction from left to right as viewed in this figure. The conversion of 
edition of the color codes of these figures are effected by the WS as 
above stated. 
Next, practical examples of the image synthesizing processing of the 
photograph or picture of FIG. 12(a) and the characters and graphic forms 
of FIGS. 14(a) and 14(b) will be described in the following cases: 
(1) the gradation levels of the C, M, Y and K halftones corresponding to 
the color code 0 of FIG. 14(a) are set to be 0, 0, 0 and 0, respectively, 
and those of the C, M, Y and K halftones corresponding to the color code 1 
of FIG. 14(a) are set to be 255, 255, 255 and 255, respectively; and 
(2) the gradation levels of the C, M, Y and K halftones corresponding to 
the color code 0 of FIG. 14(a) are set to be 0, 0, 0 and 0, respectively, 
and those of the C, M, Y and K halftones corresponding to the color code 1 
of FIG. 14(a) are set to be 64, 64, 64 and 64, respectively. 
Further, practical examples of the image synthesizing processing of the 
photograph or picture of FIG. 12(a) and the characters and graphic forms 
of FIGS. 14(a) and 14(b) will be described in the following cases: 
(3) the gradation levels of the C, M, Y and K halftones corresponding to 
each of the color codes 0 and 2 of FIG. 14(b) are set to be 0, 0, 0 and 0, 
respectively, and those of the C, M, Y and K halftones corresponding to 
the color code 1 of FIG. 14(b) are set to be 255, 255, 255 and 255, 
respectively; and 
(4) the gradation levels of the C, M, Y and K halftones corresponding to 
the color codes 0 and 2 of FIG. 14(b) are set to be 0, 0, 0 and 0, 
respectively, and those of the C, M, Y and K halftones corresponding to 
the color code 1 are set to be 64, 64, 64 and 64, respectively. 
FIGS. 16(a) and (b) show the results of the extraction and image 
synthesizing processing of the dot patterns of the photograph or picture 
of FIG. 12(a) and the characters and graphic forms of FIGS. 14(a) and 
14(b) represented by one of the C, M, Y and K halftones. FIG. 16(a) shows 
an example of the result of the synthesizing processing in case where only 
portions corresponding to the color code 1 indicating the characters are 
objects to be extracted and synthesized and portions corresponding to the 
color code 0 indicating the background are not objects to be extracted and 
synthesized. In case of this figure, the gradation levels of the C, M, Y 
and K halftones corresponding to the color code 1 are set to be 255, 255, 
255 and 255, respectively, as described above. On the other hand, FIG. 
16(b) shows another example of the result of the synthesizing processing 
in case where only portions corresponding to the color code 1 indicating 
the characters are objects to be extracted and synthesized. In this case, 
the gradation levels of the C, M, Y and K halftones corresponding to the 
color code 1 are set to be 64, 64, 64 and 64, respectively, as stated 
above. FIG. 17(a) illustrates bi-level dot data corresponding to a line a 
of FIG. 16(a); and FIG. 17(b) shows bi-level dot data corresponding to a 
line b of FIG. 16(b). 
Next, examples of the results of the image synthesis processing of FIGS. 
18(a) and 18(b) will be described hereinbelow. These figures illustrate 
the results of the extraction and image synthesizing processing of the dot 
patterns of the photograph or picture of FIG. 12(a) and the characters and 
graphic forms of FIGS. 14(a) and 14(b) represented by one of the C, M, Y 
and K halftones. FIG. 18(a) shows an example of the result of the 
synthesizing processing in case where only portions corresponding to the 
color codes 1 and 2 respectively indicating the characters and the frames 
are objects to be extracted and synthesized and portions corresponding to 
the color code 0 indicating the background are not objects to be extracted 
and synthesized. In case of this figure, the gradation levels of the C, M, 
Y and K halftones corresponding to the color code 1 are set to be 255, 
255, 255 and 255, respectively, and those of the C, M, Y and K halftones 
corresponding to the color code 2 are set to be 0, 0, 0 and 0, 
respectively. On the other hand, FIG. 18(b) shows another example of the 
result of the synthesizing processing in case where only portions 
corresponding to the color codes 1 and 2 respectively indicating the 
characters and the frames are objects to be extracted and synthesized. In 
this case, the gradation levels of the C, M, Y and K halftones 
corresponding to the color code 1 are set to be 64, 64, 64 and 64, 
respectively, and those of the C, M, Y and K halftones corresponding to 
the color code 2 are set to be 0, 0, 0 and 0, respectively. The dot 
patterns corresponding to the characters and graphic forms of FIGS. 16(a), 
16(b), 18(a ) and 18(b) are made to be different from those corresponding 
to the photograph or picture. Namely, the number of halftone-dot lines and 
the halftone-dot angle of the halftone dot patterns corresponding to the 
characters and graphic forms are small in comparison with those of the 
halftone dot pattern corresponding to the photograph or picture. Namely, 
the former patterns are coarse in comparison with the latter pattern. 
Thus, the halftone-dot patterns corresponding to color codes indicating 
the characters and graphic forms can be different in the number of 
halftone-dot lines and the halftone-dot angle from each other. As a 
result, various image effects can be obtained. 
Incidentally, FIG. 19(a) illustrates bi-level dot data corresponding to a 
line a of FIG. 18(a); and FIG. 19(b) illustrates bi-level dot data 
corresponding to a line b of FIG. 18(b). The bi-level dot patterns of 
FIGS. 199a) and 19(b) are different from those of FIGS. 17(a) and 17(b) in 
that each of the characters is hemmed by a white frame. The dot percent of 
the portion corresponding to the characters in the dot patterns of FIGS. 
18(a) and 19(a) is nearly 100%. In contrast, that of the portion 
corresponding to the characters in the dot patterns of FIGS. 18(b) and 
19(b) is 30% or so. 
In the foregoing description, the results of the image synthesizing 
processing of practical examples of the picture, characters and graphic 
forms including whit frames of the characters as shown in FIG. 14(a) have 
been explained. Various pictures, characters and graphic forms can be 
extracted in other manners and synthesized. For example, another color 
code 3 is used to indicate the inside of a rectangular region hemming each 
character and extract the rectangular region. Furthermore, the extraction 
and image synthesis can be performed even in case where run-length 
encoding code data represents bi-level dot patterns of the characters and 
graphic forms are bi-level. Practically, a color code, for instance, 1 is 
assigned to black dots in the character regions; another color code 2 is 
assigned to white dots in the character regions; and further another code 
0 is assigned to the background outside the character regions. Such 
assignment is realized by effecting the conversion and edition of the data 
in the external WS. FIG. 20 illustrates an example in which the color 
codes 1 and 2 are assigned to the white dots and the background, 
respectively, by an edition in the WS. Incidentally, an editing operation 
of providing frames to the outside or inside of the halftone-dot character 
regions can be performed by the WS by assigning a color code 4 to the 
frames. 
While a preferred embodiment of the present invention has been described 
above, it is to be understood that the present invention is not limited 
thereto and that other modifications will be apparent to those skilled in 
the art without departing from the spirit of the invention. The scope of 
the present invention, therefore, is to be determined solely by the 
appended claims.