Image display system

An image display system suitable for use in displaying, at an enlarged scale, any desired portion of an image presented on a picture surface of a display apparatus, or in displaying, in a reduced scale, the whole portion of the image presented on the picture surface. The picture surface is divided into sub-regions arranged in m lines and n columns. Sub-region appointing numeral keys are arranged to correspond to these sub-regions, so that any desired sub-region is appointed by a depression of the corresponding appointing keys, thus designating that to make the image portion in the appointed sub-region be enlarged and displayed over the entire area of the picture surface or that the whole part of the image on the display surface be reduced and displayed in the appointed sub-region of the picture surface.

BACKGROUND OF THE INVENTION 
The present invention relates to an image display system and, more 
particularly, to an image display system capable of easily performing an 
enlargement and reduction of scale of an image formed on the image surface 
of a graphic display apparatus. 
The graphic display apparatus has a variety of uses as means for realizing 
various techniques using computers such as CAD (Computer-Aided-Design), 
CAM (Computer-Aided Manufacture) and the like. For instance, the graphic 
display apparatus is effectively utilized in instantaneously drawing the 
locus of movement of a tool or the shape of the work, in the operation of 
NC (Numerical Control) machine tool to permit the check of NC processing 
program. 
In the use of the graphic display apparatus for displaying an image, it is 
an indispensable function to be able draw the picture of any desired 
portion of the image at any desired magnification. To this end, it is 
necessary to appoint the region of the image to be displayed at an 
enlarged or reduced scale, as well as the magnification. 
Hitherto, this appointment has been made either by (1) directly appointing 
the region on the image surface with a light pen, a joy stick or a tablet 
or by (2) inputting numerical data concerning the coordinate values of the 
region to be displayed and the magnification through a keyboard. 
The first appointing method (1) however, is impractical in that it requires 
an expensive light pen, tablet or the like. The second appointing method 
(2) is also defective in that it requires a highly complicated and 
troublesome operation for inputting the coordinate information and that 
the appointment of the region cannot be made promptly. 
In the techniques concerned with the image display, particularly in the NC 
processing or machining, it is desirable to display, simply, rapidly and 
at low cost, only the desired portion of the image at an enlarged or 
reduced scale. Unfortunately, the aforementioned conventional appointing 
methods (1) and (2) fail to meet this requirement. 
Accordingly, there is an increasing demand for an image display system 
which can easily and rapidly appoint the region of the image to be 
displayed and enlarge or reduce the scale at which the image is displayed. 
SUMMARY OF THE INVENTION 
It is, therefore, a an object of the invention to provide an image display 
system which permits any desired region on the image surface to be 
appointed by quite an easy operation. 
More specifically, it is an object of the invention to provide an image 
display system which permits any desired region of the image on an image 
surface to be appointed and displayed at an enlarged or reduced scale by 
quite an easy manipulation. 
It is another object of the invention to provide an image display system 
which permits any desired region of image on a picture surface to be 
appointed promptly and displayed at an enlarged or reduced scale. 
It is still another object of the invention to provide an image display 
system in which any desired region of the image on a picture surface is 
appointed and displayed at an enlarged or reduced scale by a simple 
manipulation of a ten-key type input device. 
It is a further object of the invention to provide an image display system 
which permits the operator to easily understand the relationship between 
the keys for appointing the regions of the image and the regions of image 
on a picture surface. 
It is a still further object of the invention to provide an image display 
system in which the keys for inputting the data can be used also as keys 
for appointing the regions of image on a picture surface. 
Other features and advantages of the invention will be apparent from the 
following description of the preferred embodiments taken in conjunction 
with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The outline of the enlargement and reduction of the scale of the display in 
accordance with the invention will be described hereunder with reference 
to FIGS. 1, 2 and 3. 
Referring first to FIG. 1 showing the relationship between the CRT surface 
(picture surface) and sub-regions, the CRT surface (picture surface) DFS 
of a graphic display device is divided into 9 sub-regions S.sub.1, 
S.sub.2, . . . S.sub.9, which are arranged in three columns and three 
lines as illustrated. 
A symbol RP represents the origin point of the image on a two-dimensional 
coordinate system. Namely, the point RP is determined as the point (O,O) 
on the coordinate system. Similarly, a symbol BRP represents the origin 
point of a picture on the two-dimensional coordinate system, given as the 
point (Ox,Oy). Symbols Z.sub.1 thru Z.sub.9 represent the reference points 
or origins of respective sub-regions S.sub.1 thru S.sub.9. Symbols lx and 
ly represent, respectively, the lengths of the picture surface in the line 
direction (X-axis direction) and column direction (Y-axis direction). The 
sub-region Si can be specified by the suffix i (i=1, 2, . . . , 9). The 
arrangement is such that the desired sub-region Si is put on display as 
the corresponding key i of a ten-key type input device is depressed. 
FIG. 2 is an illustration of the relationship between the sub-regions Si of 
the picture surface CRT and the keys of the ten-key type input device TK. 
The ten-key type input device TK includes a "0" key K0, "1" key K.sub.1, 
"2" key K.sub.2, . . . "9" key K.sub.9 and a decimal point key Kp. The "i" 
key K.sub.i corresponds to the sub-region S.sub.i, so that any desired 
sub-region S.sub.i is appointed when the corresponding key K.sub.i is 
depressed. 
It is to be noted here that the arrangement of the sub-regions on the 
picture surface, i.e. the lines and columns of the sub-regions, perfectly 
corresponds to the arrangement of the keys, so that the appointment of the 
sub-region to be displayed at an enlarged or reduced scale can be made in 
quite an easy way. The "0" key K0 and the decimal point key Kp are used 
also as an input keys for inputting a magnification order of "3 times" and 
"1/3 time", respectively. Needless to say, it is possible to provide an 
input key or keys for inputting any suitable magnifications. 
FIG. 3 comprising 3(a) and 3(b) illustrates how the scale of display of the 
image is enlarged or reduced in the image display system of the invention. 
For displaying a specific portion of the image at the enlarged scale, the 
sub-region involving the above-mentioned portion of the image is appointed 
by the depression of a corresponding key. As a result, as will be seen 
from FIG. 3(a), the image portion in the sub-region S.sub.i (S.sub.4 in 
the illustrated example) is displayed to occupy the whole area of the 
picture surface DFS, with the reference point Z.sub.4 constituting the new 
origin point of the picture. In this state, the image portion in the 
sub-region Si of the original image is increased by three times in both of 
line and column directions. In contrast, when displaying a specific 
portion of the image at reduced scale, the image displayed on the whole 
area of the picture surface DFS is shown at a scale reduced to 1/3 in both 
of line and column directions, on the sub-region S.sub.i (S.sub.4 in the 
illustrated example) on the picture surface, as the sub-region S.sub.i is 
appointed. Consequently, the whole image spreading over the entire area of 
the region AS defined by thick lines is displayed to occupy the whole part 
of the picture surface DFS, at a size reduced to 1/3 in both line and 
column directions, as will be seen from FIG. 3(b). It will be seen that 
the area of the region AS is 9 times as large as the area of the picture 
surface DFS. 
According to the invention, the operation for displaying the image portion 
of the sub-region S.sub.4 at a magnification 3 over the entire area of the 
picture surface DFS is conducted in a procedure having the steps of: --1-- 
depression of numeral key K.sub.4 corresponding to the designated 
sub-region S.sub.4, --2-- depression of "0" key K.sub.0 and --3-- 
depression of execution key (not shown) for instructing the execution of 
enlargement or reduction of the scale of display. 
In contrast, the operation for displaying the image occupying the whole 
area of the picture surface DFS at a scale reduced to 1/3 in the 
sub-region S.sub.4 as shown in FIG. 3b is conducted by a process having 
the steps of: (1) depression of the numeral key K.sub.4 corresponding to 
the designated sub-region S.sub.4, (2) depression of the decimal point key 
Kp and (3) depression of the execution key. 
Namely, according to the invention, the operation for displaying the 
desired portion of the image at an enlarged scale is conducted by the 
process having the following steps: 
1. depression of the numeral key corresponding to the sub-region to which 
the portion of the image to be displayed at an enlarged scale belongs, 
2. depression of the "0" key K.sub.o for enlarging the scale, and 
3. depression of the execution key. 
In contrast, the operation for displaying the image at a reduced scale is 
conducted by the process having the following steps: 
1. depression of the numeral key corresponding to the sub-region in which 
the reduced image is to be put; 
2. depression of the decimal point key Kp for the reduction of scale; and 
3. depression of the execution key. 
In the display of the image at an enlarged or reduced scale, once the new 
picture origin point is determined by the inputting of the region to which 
the image portion to be displayed at enlarged scale belongs or the region 
in which the image of reduced scale is to be put, the display at enlarged 
or reduced scale as shown in FIG. 3(a) or 3(b) is achieved in a known 
graphic display technique. In the case of the display at the enlarged 
scale as shown in FIG. 3(a), the reference point Z.sub.4 constitutes the 
new picture origin point, while, in the display at reduced scale shown in 
FIG. 3(b), the point SDP constitutes the new picture origin point. 
FIG. 4 shows a flow chart of the process for determination of the new 
picture origin point by the appointment of the sub-region Si through the 
aforementioned ten-key type input device TK. 
First of all, the data concerning the initial picture origin point (Ox, Oy) 
and the desired magnification S is input to make the picture surface DFS 
display the image in accordance with the picture information corresponding 
to this input. (FIG. 1) 
Thereafter, operations are executed for displaying the image portion in the 
predetermined sub-region at an enlarged scale or for displaying an image 
at a reduced scale in the predetermined sub-region as shown in FIGS. 3(a) 
and 3(b). To this end, a numeral key K.sub.i corresponding to the 
designated sub-region is depressed (See FIG. 2). In consequence, the 
position of the reference point (n.sub.x, n.sub.y) of the aforementioned 
sub-region is calculated on an assumption of n.sub.x =i and n.sub.y =1. 
Namely, an arithmetic operation is made to determine to what line and 
column the designated sub-region belongs. Since the picture surface is 
divided into 9 sub-regions arranged in three lines and three columns, a 
judgement is made at first as to whether the n.sub.x (=i) is greater than 
3. If n.sub.x is not greater than 3 (n.sub.x .ltoreq.3), the sub-region 
appointed by the numeral key K.sub.i is the sub-region which is located in 
the first line and the i th column. If n.sub.x (=i) is greater than 3 
(n.sub.x &gt;3), the sub-region appointed by the numeral key K.sub.i is the 
sub-region which is located in the second or third line. In this case, 
arithmetic operations of (n.sub.x -3).fwdarw.new n.sub.x (namely, 
(i-3).fwdarw.new n.sub.x) and (n.sub.y +1).fwdarw.new n.sub.y (namely, 
(1+1).fwdarw.new n.sub.y) are conducted to make a judgement as to the new 
n.sub.x, i.e. a judgement as to whether n.sub.x (=i-3) is greater than 3. 
If n.sub.x is not greater than 3 (n.sub.x .ltoreq.3), the sub-region 
appointed by the numeral key K.sub.i is the region in the second line and 
(i-3)th column. However, when the n.sub.x (=i-3) is greater than 3 a 
second time, the sub-region appointed by the numeral key K.sub.i is the 
one which is in the third line. In this case, arithmetic operations of 
(n.sub.x -3).fwdarw.n.sub.x, i.e. [(i-3)-3].fwdarw.new n.sub.x) and 
(n.sub.y +1).fwdarw.new n.sub.y, i.e. (2+1).fwdarw.new n.sub.y are 
conducted. As a result, the new n.sub.x is not greater than 3 (n.sub.x 
.ltoreq.3), so that it is judged that the sub-region appointed by the 
numeral key K.sub.i is of the line n.sub.y (third line) and column n.sub.x 
(line i-6). 
In the case where the portion of the original image is displayed at the 
enlarged scale, the picture surface DFS has insufficient display capacity 
for the original image. To the contrary, the display capacity is 
excessively large when the original image is displayed at the reduced 
scale. 
Therefore, the lengths in line and column directions of each sub-region on 
the image surface, before the enlargement or reduction of the scale at 
magnification S, are calculated as follows: 
EQU d.sub.x =lx/S (1) 
EQU d.sub.y =ly/S (2) 
Then, the scale enlargement information or scale reduction information is 
input together with the magnification information S. In the illustrated 
embodiment, however, the scale enlargement information or the scale 
reduction information is input solely, because the magnification S is 
fixed at 3 and 1/3 for the scale enlargement and scale reduction, 
respectively. Consequently, an arithmetic operation of 
3.times.S.fwdarw.new S is performed in the case of the scale enlargement, 
whereas, in the case of the scale reduction, an arithmetic operation of 
S/3.fwdarw.new S is performed. At the same time, an origin point 
calculation factor f=1/3 is set in the case of the scale enlargement, 
while an origin point calculation factor f=-1 is set in the case of the 
scale reduction. 
Then, as the execution key is depressed, calculations are performed as 
follows to determine the new picture origin point. 
EQU O.sub.x +d.sub.x .multidot.(n.sub.x -1).multidot.f.fwdarw.O.sub.x (3) 
EQU O.sub.y +dy.multidot.(n.sub.y -1).multidot.f.fwdarw.O.sub.y (4) 
Thereafter, the display at enlarged or reduced scale is performed by a 
known method, in accordance with the above-mentioned new picture origin 
point (O.sub.x,O.sub.y), new magnification S and the picture information 
of the picture memory using this new origin point as the starting point. 
In the described embodiment, the picture surface DFS is divided into 9 
sub-regions arranged in three lines and three columns, so that the 
magnification is 3 and 1/3, respectively, in the cases of the scale 
enlargement and scale reduction. 
The above-mentioned magnification, however, is not exclusive and it is 
possible to obtain any desired magnification by dividing the picture 
surface into sub-regions arranged in m lines and n columns. In such a 
case, the sub-region of line i and column j is specified by a numerical 
code of 
EQU N=[(i-1).sub.n +j] (3) 
Therefore, the appointment of the sub-region is achieved by inputting the 
above-mentioned numerical code N which specifies the sub-region, and the 
new picture origin point (O.sub.x, O.sub.y) and magnification S are 
calculated in a series of operations shown by the flow chart in FIG. 6. 
Since the flow chart shown in FIG. 6 is materially identical to that shown 
in FIG. 4 except that the flow chart in FIG. 6 is utilized in the case 
that the picture surface is generally divided into sub-regions arranged in 
m lines and n columns, it seems that there is no necessity for the 
explanation of the flow chart shown in FIG. 6. Herein, m and n are 
arbitrary numeric integers, respectively. 
If the number of lines (m) equals to the number of columns (n), a 
magnification of m and 1/m is obtained for each case of the scale 
enlargement and scale reduction. Namely, in the case of the scale 
enlargement, the portion of the image shown in a sub-region is displayed 
at an enlarged scale to occupy the whole area of the picture surface, 
whereas, in the case of the scale reduction, the image occupying the whole 
area of the image surface is reduced in size to occupy only the specified 
sub-region in the picture surface. 
FIG. 7 is a circuit block diagram of the calculation means for calculating 
the picture origin point and magnification, in accordance with another 
embodiment of the invention. 
In FIG. 7, symbols TK, EK and CRT represent, respectively, a ten-key type 
input device, an execution key and a cathode ray tube having the picture 
surface. A picture memory is represented by a symbol PM. A picture 
processing circuit PPC constructed to make a display of the picture at a 
predetermined scale on the cathode ray tube CRT, in accordance with 
information concerning the picture origin point (O.sub.x,O.sub.y), 
magnification S and picture information PI, upon depression of the 
execution key EK. 
A symbol PZMC represents a circuit for calculating the picture origin point 
and magnification. Namely, the circuit PZMC performs the arithmetic 
operations and judgements of the flow chart shown in FIG. 4 to determine 
the new picture origin point (O.sub.x,O.sub.y) and the new magnification 
S. 
The circuit PZMC includes a distribution circuit 101 which is constructed 
to determine whether the depressed key is a numeral key (one of the keys 
"1" to "9") or a magnification key (either "0" key or decimal point key) 
and, when the depressed key is a numeral key, supplies a numeral code 
(1.ltoreq.i.ltoreq.9) to a line l.sub.1 and "0" or decimal point code to 
the line l.sub.2 when the depressed key is the "0" key or the decimal 
point key. A reference numeral 102 designates a register in which n.sub.x 
=i and n.sub.y =1 are set when the numeral i is delivered to the line 
l.sub.1, while a numeral 103 designates a judging circuit which is adapted 
to deliver an operation command signal OP.sub.1 to a line l.sub.3 when 
n.sub.x is greater than 3 (n.sub.x &gt;3) and an operation command OP.sub.2 
to a line l.sub.4 when n.sub.x is not greater than 3 (n.sub.x .ltoreq.3). 
A reference numeral 104 designates an operation circuit for calculating 
the new origin point n.sub.x,n.sub.y. More specifically, this circuit 104 
performs a calculation of (n.sub.x -3), (n.sub.y +1) using the numerical 
values n.sub.x,n.sub.y set in the register 102, upon receipt of the 
operation command signal OP.sub.1 ="1" (high level), and sets the new 
n.sub.x and new n.sub.y in the register 102. A reference numeral 105 
designates a register adapted to memorize the d.sub.x and d.sub.y, while a 
numeral 106 denotes an operation circuit for calculating the d.sub.x and 
d.sub.y upon receipt of the operation command signal OP.sub.2 ="1" (high 
level). A register 107 is constructed to memorize the picture origin point 
(O.sub.x,O.sub.y), while a register 108 is constructed to memorize the 
magnification S (scale enlargement or scale reduction) and the origin 
point calculation factor f. A reference numeral 109 designates a picture 
origin point calculation circuit constructed for determining the new 
picture origin point through performing the operations shown by equations 
(3) and (4), and setting the thus determined origin point in the register 
107. A reference numeral 110 designates a judging circuit constructed to 
make a judgement as to whether the code delivered to the line l.sub.2 is 
the "0" code or the decimal point code. This judging circuit 110 delivers 
a signal "1" to a line l.sub.5 when the code delivered to the line l.sub.2 
is the "0" code, and a signal "1" to a line l.sub.6 when the delivered 
code is the decimal point code. 
A reference numeral 111 designates a magnification calculation circuit 
constructed to perform an arithmetic operation of S/3=S and generate 
origin point calculation factor f when the signal "1" is delivered to the 
line l.sub.6. The thus calculated origin point calculation factor f and 
the new magnification S are memorized in the resistor 108. A reference 
numeral 113 designates a control circuit adapted to control the timings of 
arithmetic operations and judgements in respective circuits, through a 
control line which is not shown. 
In operation, after a depression of a numeral key K.sub.i for appointing 
the sub-region, the "0" key or the decimal point key is depressed to give 
an order for scale enlargement or reduction and, thereafter, the execution 
key EK is depressed. 
Consequently, the circuit PZMC for calculating the picture origin point and 
magnification makes judgements and arithmetic operations in accordance 
with the flow shown by the flow chart in FIG. 4, under the control of the 
controller 113, while the picture processing circuit PPC conducts known 
processing in accordance with the new picture origin point 
(O.sub.x,O.sub.y), new magnification S and the picture information PI, to 
make the display on the cathode ray tube CRT at an enlarged or reduced 
scale. 
FIG. 8 shows the outline of the scale enlargement and scale reduction in 
accordance with another embodiment of the invention. A symbol DFS 
represents the CRT (picture surface) incorporated in a graphic display 
apparatus. The picture surface DFS is divided into 9 sub-regions S.sub.1 
to S.sub.9 of an equal size arranged in three lines and three columns. In 
this embodiment, there is a concept of an imaginary sub-region. Namely, an 
imaginary sub-region is the region which has the same shape as the 
sub-region and has a neutral or central line which coincides with the 
border line between two adjacent sub-regions, as shown by the broken line. 
Also, an area having the same shape as the sub-region and centered at the 
point of contact between two diagonally contacting two sub-regions 
(reference points Z.sub.5,Z.sub.6,Z.sub.8,Z.sub.9) is referred to as an 
imaginary sub-region. A symbol BRP represents the picture origin point 
(O.sub.x,O.sub.y) on a two-dimensional coordinate system, whereas RP 
represents the origin point of the original image given as the point (O,O) 
of the coordinate system. Symbols l.sub.x and l.sub.y represent the 
lengths of the picture surface in the line direction (X-axis direction) 
and column direction (Y-axis direction). 
The embodiment shown in FIGS. 1 to 7 is adapted to enlarge the image 
portion in a specific sub-region to the size occupying the whole area of 
the picture surface or to reduce the image occupying the whole area of the 
picture surface into a size occupying the specified region of the picture 
surface. In contrast, the embodiment described in connection with FIG. 8 
permits an appointment of an imaginary sub-region, so that the image 
portion in the imaginary sub-region is enlarged to occupy the whole area 
of the picture surface or, alternatively, the image spread over the entire 
area of the picture surface is reduced in size and displayed in the 
appointed sub-region. 
The appointment of the imaginary sub-region is made by appointing two 
sub-regions between which the designated imaginary sub-region is located. 
FIG. 9 shows how to appoint the imaginary sub-region. It will be seen that 
the imaginary sub-region as shown by the broken line is appointed by 
successive inputting of the sub-regions S.sub.k and S.sub.m. The 
sub-region S.sub.i is specified by the numerical value i. Namely, the 
sub-region S.sub.i is input by a depression of the key K.sub.i of the 
ten-key type input device. 
Namely, the display of the image at an enlarged scale is made by the 
following procedure. 
1. depression of the numeral key K.sub.k corresponding to one S.sub.k of 
the sub-regions between which the designated imaginary region is located; 
2. depression of the key K.sub.m corresponding to the another S.sub.m of 
the sub-regions; 
3. depression of "0" key K.sub.o for giving an order for display at 
enlarged scale; and 
4. depression of the execution key EK. 
Similarly, the display of the image at a reduced scale is made by the 
following procedure: 
1. depression of numeral key K.sub.k corresponding to one S.sub.k of the 
sub-regions disposed at both sides of the imaginary sub-region in which 
the image of the reduced size is to be put; 
2. depression of the numeral key K.sub.m corresponding to another S.sub.m 
of the sub-regions; 
3. depression of the decimal point key K.sub.p for giving an order for 
display of the image at reduced scale; and 
4. depression of the execution key. 
In the enlargement of the image of the imaginary sub-region or in the 
reduction of the image into the imaginary sub-region, the display at 
enlarged scale or reduced scale is made as shown in FIG. 10(a) or 10(b), 
by the known graphic display technique, once the new picture origin point 
is determined. For information, in the case of the scale enlargement as 
shown in FIG. 10(a), the point ZP constitutes the new picture origin 
point, whereas, in the scale reduction as shown in FIG. 10(b), the point 
SDP constitutes the new picture origin point. 
FIG. 11 shows the flow chart of a process in which the picture origin point 
is determined when the designated imaginary sub-region is appointed by the 
inputting of two sub-regions S.sub.m and S.sub.k (m,k=1,2 . . . 9) by 
means of the ten-key type input device. 
First of all, the initial picture origin point (O.sub.x, O.sub.y) and 
magnification S are input to display the image on the picture surface DFS 
in accordance with the picture information memorized in the picture 
memory. 
Then, the image shown in the sub-region is enlarged or the image shown over 
the entire area of the picture surface is reduced in scale and shown in 
the appointed imaginary sub-region, as shown in FIGS. 10(a) and 10(b). To 
this end, the numeral key K.sub.k corresponding to one S.sub.k of the two 
regions S.sub.k,S.sub.m (FIG. 9) disposed at both sides of the imaginary 
sub-region is depressed. In consequence, an arithmetic operation similar 
to that shown in FIG. 4 is performed on the assumption of K.sub.k =k and 
K.sub.y =1 to determine the line and column to which the sub-region 
S.sub.k belongs. 
Thereafter, the numeral key Km corresponding to the sub-region Sm is 
depressed, so that the line and column to which the sub-region S.sub.m 
belongs are determined, on an assumption of m.sub.x =m and m.sub.y =1. 
After the completion of the above-explained arithmetic operation, the 
following arithmetic operations are performed. 
EQU n.sub.x =(k.sub.x +m.sub.x)/2 (5) 
EQU n=(k.sub.y +m.sub.y)/2 (6) 
Thereafter, the new magnification S and the new picture origin point 
(O.sub.x,O.sub.y) are calculated in accordance with the flow chart shown 
in FIG. 11 to permit the display at the enlarged or reduced scale. 
Although the picture surface DFS in this embodiment also is divided into 9 
sub-regions arranged in 3 lines and 3 columns to provide magnifications of 
3 and 1/3, respectively, for the scale enlargement and reduction, this is 
not exclusive and the picture surface may be divided into sub-regions 
arranged in m lines and n columns to provide any desired magnification. 
FIG. 12 shows the block diagram of the circuit for calculating the new 
picture origin point and magnification. In this Figure, the same reference 
numerals are used to denote the same parts as those shown in FIG. 7. 
A reference numeral 201 designates a register adapted to memorize 
k.sub.x,k.sub.y,m.sub.x and m.sub.y. This register makes a setting of 
k.sub.x =k, k.sub.y =1 (mx=m, my=1) when the line l receives a numerical 
value k(m), and memorizes the thus calculated k.sub.x,k.sub.y,m.sub.x and 
m.sub.y. A reference numeral 202 denotes a judging circuit which is 
adapted to make a judgement as to whether the k.sub.x (m.sub.x) is greater 
than 3, i.e. k.sub.x &gt;3(m.sub.x &gt;3)amd delivers, when the condition of 
k.sub.x &gt;3(M.sub.x &gt;3) is satisfied, an operation command signal OP.sub.1 
to a line l.sub.11. When this condition is not met, i.e. in the case of 
k.sub.x .ltoreq.3(m.sub.x .ltoreq.3), this circuit delivers an operation 
command signal OP.sub.2 to a line l.sub.12. 
A reference numeral 203 designates a circuit for calculating the new 
k.sub.x,k.sub.y (new m.sub.x,m.sub.y). Namely, this circuit makes 
arithmetic operations of (k.sub.x -3), )k.sub.y +1), (m.sub.x -3), 
(m.sub.y +1) upon receipt of the operation command signal OP.sub.l, and 
sets the thus calculated new k.sub.x and new k.sub.y (new m.sub.x, new 
m.sub.y) in the register 201. A reference numeral 204 designates an 
arithmetic operation circuit for determining the n.sub.x,n.sub.y through 
calculations expressed by the equations (5) and (6), using the new 
k.sub.x, new k.sub.y, new m.sub.x and new m.sub.y, while a register for 
memorizing the n.sub.x and n.sub.y thus determined is denoted by a 
reference numeral 205. 
In operation, numeral keys K.sub.k and K.sub.m of the ten-key type input 
deive are depressed to appoint the imaginary region. Thereafter, the "0" 
key or the decimal point key K.sub.p is depressed to give an order for 
enlargement or reduction of the scale of display. Finally, the execution 
key EK is depressed. In consequence, the circuit PZMC for calculating the 
picture origin point and magnification makes a judging and arithmetic 
operation in accordance with the flow chart shown in FIG. 11, under the 
control of the controller 113, thereby displaying the image on the cathode 
ray tube CRT at the enlarged or reduced scale. 
As has been described, according to the invention, the picture surface such 
as cathode ray tube CRT is divided into a plurality of sub-regions so that 
it is possible to simply and promptly appoint the sub-region for the 
display of the image at enlarged or reduced scale. 
Particularly, when the picture surface is divided into 9 sub-regions 
arranged in 3 lines and 3 columns, it is possible to obtain a sub-region 
arrangement Si which corresponds to the arrangement of numeral keys 
K.sub.i of the ten-key type input device. Such an arrangement provides, 
needless to say, an appointment of the sub-region that can be made 
extremely easily and promptly without fail. Generally, the information 
processing apparatus with the display function is provided with the 
ten-key type input system. According to the invention, it is possible to 
make an efficient use of this ten-key type input device as the key device 
for appointing the sub-region, so that the cost of the display system is 
reduced and the construction of the same is simplified remarkably. 
It is also to be noted that, according to the invention, it is possible to 
obtain a display system which is easy to operate, because it is possible 
to enlarge the image in an intermediate sub-region (imaginary sub-region) 
between two adjacent sub-regions or to reduce the image in size to fit the 
above-mentioned intermediate or imaginary sub-region. .