JPH0777416B2 - Image processing device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an image in which an image represented by input scan data is subjected to a rotation process and a scaling process in the scanning direction and a vertical direction thereof at magnifications α and β, respectively. Regarding a processing device.

<Prior Art> Conventionally, a device for rotating and enlarging / reducing a digital image is
The processing was executed after the input image data was loaded into the shared memory. However, in general, the input image has a larger amount of information than the processed image data, and storing the input image information requires a larger memory capacity than storing the processed image information. The method of fetching the image information in the shared memory is disadvantageous in terms of cost and circuit scale of the memory, as compared with the method of processing in synchronization with the input scanning synchronization signal and sequentially outputting the processed data to the output memory.

On the other hand, in the processing of sequentially rotating and enlarging / reducing the scan input image data in synchronization with the scan synchronization signal, the processed data does not match the output pitch, and the image is missing or misaligned. It had a drawback that deterioration occurred. An example is shown in FIG. FIG. 1a shows the original picture pitch. The dashed line in Figure 1b shows the output pitch,
The solid line shows the pitch of the image obtained by rotating the original image by 35 °. Each square represents a pixel, and each output pixel (dotted square) consisting of an output pitch is hatched when the pixel of the rotated image is associated with that pixel. This indicates that the output pixel is a missing pixel (a pixel that has no associated image data). Figure 2c
Is rotated by 38 degrees and reduced by 80% in the main scanning direction, 120 in the sub scanning direction.
Similar to FIG. 1b, the missing pixels in the case where the% enlargement process is performed are shown.

<Purpose> The present invention has been made in view of the above points, and performs rotation processing on an image represented by input scan data, and at the same time, performs scaling processing with magnifications α and β in the scanning direction and its vertical direction, respectively. It is an object of the present invention to provide an image processing device capable of obtaining a high-quality converted image at high speed without requiring a memory for storing input image data in frame units.

<Embodiment> FIGS. 1 and 3 to 11 show an embodiment of the present invention, FIG. 1 is a basic configuration diagram of this embodiment, and FIG. 3a is a block diagram of a circuit of the whole embodiment. The first half, and FIG. 3b is the latter half. FIG. 4 is a more detailed block diagram of the coordinate detection circuit after the rotation / independent scaling processing of FIG. 3a, and FIG. 5 is the in-region lattice point detection circuit after the rotation / independent scaling processing of FIG. 3b. 6 is a more detailed block diagram of FIG. 6, FIG. 6 is a more detailed block diagram of the coordinate conversion (inverse conversion) circuit of FIG. 3b, and FIG. 7 is FIG. 3b.
3 is a more detailed block diagram of the interpolation processing circuit of FIG. 8th
The figure shows the scanning state of the image. FIG. 9 shows the relationship between the page sync signal and the sub-scan sync signal. FIG. 10 shows the relationship between the sub scanning synchronization signal and the main scanning synchronization signal. FIG. 11 shows the configuration of the raster memory and the relationship with the scan data. FIG. 12 shows the execution state of the interpolation processing. FIG. 13 illustrates a method of obtaining interpolated output image data from rotated input scan image data.

Here, the main scanning direction of the original image is considered to be the x-axis direction, and the sub-scanning direction is considered to be the y-axis direction, and the sub-scanning synchronization signal is used as a base point and is associated with the coordinates 1, 2, 3, ... Also, with the page synchronization signal as a starting point, y
Corresponds to the axial coordinates 1, 2, 3 ... That is, (x ₀ ,
y ₀ ) corresponds to the x ₀ dot of the y ₀ raster of the original picture (FIGS. 7, 9, and 10).

In Cartesian coordinates _{(x, y) (x c} , y c) the points in the coordinates of the coordinates rotated by θ as the rotation around the point (x ', y') When, (x ', y') And (x, y), (x _c , y _c ), the relation between θ is Can be expressed as

Further, with respect to the point at the coordinates of (x ′, y ′) with the point of (x _z , _yz ) as the scaling center, the coordinates after independent scaling of α times in the main scanning direction and β times in the sub scanning direction are performed. (X ″, y ″) The relationship is established.

The point at the coordinates (x, y) is rotated by θ with the point of (x _c , y _c ) as the center of rotation, and (x _z , y _z ) is the center of magnification change, α times in the main scanning direction and sub-scanning. When independent scaling of direction β times is executed,
If the resulting coordinates are (x ″, y ″), then from equations (1) and (2), The relationship is established. When the equation (3) is modified, it becomes the equation (3) ′.

11b and 11c show the input scan image and the scan image that has been subjected to the rotation / independent scaling processing. FIG. 11b is the current image, and FIG. 11c is the image after rotation / independent scaling processing.
x is the center of rotation and the center of magnification (that is, when the center of rotation and the center of magnification are the same).

By the way, α and β in equation (3) are generally rational numbers, and
Since cos θ and sin θ are generally irrational numbers, x, y, x _c , y _c , x
_{Even if z} and _yz are natural numbers, x ″ and y ″ are irrational numbers. That is, the scanned image after the rotation / independent scaling processing comes to a position displaced from the pixel (dot) position associated with the input / output synchronization signal.

The value of each pixel of the image after the rotation / independent scaling processing is determined based on the data of three continuous rasters. Α (| s in the main scanning direction centered on the center of the pixel of interest in the second raster (center raster) of the three consecutive rasters
inθ | + | cosθ |) is the length of one side and β in the sub-scanning direction
Assuming a rectangle with a length of (| sinθ | + | cosθ |),
Output pixels centered within this rectangle are detected. Circles (A, B) in FIG. 13a indicate detected pixels. These, A, B
Can be obtained by using the data of four rotated rasters surrounding the pixel. The case of paying attention to A is shown in FIG. The value of A is determined from the value having 4 pixels of a, b, c, d surrounding A. FIG. 13c shows the determination method. A line segment connecting the center of pixel b and the center of pixel d (hereinafter line segment
(referred to as bd), when a straight line is drawn from the center of the pixel A in parallel with a straight line passing through the center of the pixel c and the center of the pixel d, the intersection of the straight line and the line segment bd internally divides the line segment bd. The internal division ratio is δ: 1−δ. Further, when a straight line is drawn from the center of the pixel A to the line segment connecting the center of the pixel c and the center of the pixel d (hereinafter referred to as the line segment cd), the line and the line segment cd are The internal division ratio at which the intersection point internally divides the line segment cd is ε: 1-ε. The values of the pixels a, b, c, d are V (a), V (b),
When V (c) and V (d) are set, V (A) of the pixel A is V (A) = (1-δ) (1-ε) V (a) + (1-δ)
Let εV (b) + δ (1-ε) V (c) + δεV (d) (4). For pixel B as well, V (B) can be similarly obtained.

Next, the operation of the embodiment will be described based on a configuration example for realizing the present invention.

In FIG. 1, when a rotation instruction is given by the operator using the operation instruction device 2, the operation instruction device sets information corresponding to the instructed rotation angle to the processing circuit 10. When the enlargement / reduction is instructed, information corresponding to the instructed reduction ratio in the main scanning direction and the instructed reduction ratio in the sub-scanning direction is set to the processing circuit 10.

When the operator gives a start instruction, the operation instruction device 2
Activates the synchronization control device 6, and the synchronization control device 6 outputs a synchronization signal to the scanning data source 4 and the processing circuit 10 to execute the operation of the device. The image data is scanned as shown in FIG. 7, the leading edge of the image of one page is designated by the trailing edge of the page sync signal, and the leading edge of each scanning line in the page is designated by the trailing edge of the sub-scan sync signal. Data is specified. Data acquisition timing of each pixel is designated by the fall of the main scanning synchronization signal (FIGS. 9 and 10).

Hereinafter, the execution of the rotation / independent variable-magnification interpolation of the processing circuit 10 in FIG. 1 will be described with reference to FIGS. The respective values of sin θ, −sin θ, and cos θ are set in the processed coordinate calculation circuit 22 and the coordinate conversion (inverse conversion) circuit 28 in accordance with the rotation angle θ designated by the operator. The values are set in the processed area grid point detection circuit 24. Further, according to the center of rotation designated by the operator, the values of the main scanning offset (rotation) and the sub scanning offset (rotation) are both set in the coordinate calculation circuit 22 and the coordinate conversion (reverse conversion) circuit 28 after processing. To be done. Further, according to the reduction ratio instructed by the operator, the respective values of the main scanning direction scaling factor α and the sub scanning direction scaling factor β are stored in the processed coordinate calculation circuit 22 and the processed area grid point detection circuit 24. , And their reciprocals 1 / α and 1 / β are set in the coordinate conversion (inverse conversion) circuit 28. Main scanning offset (magnification) according to the magnification center designated by the operator,
Each value of the sub-scan offset (magnification change) is set in the coordinate calculation circuit 22 and the coordinate conversion (inverse conversion) circuit 28 after processing.

The scanning data source outputs the image data as scanning data to the raster memory 10 in accordance with the synchronization signal output from the synchronization control device 6. The structure of the raster memory 10 is shown in FIG. 4 line memories corresponding to 4 scan lines 10-1
One of 10 to 10-4 takes in image data from the scanning data source 4, and the other three take as input data, and the rotation / independent variable-magnification interpolation process is executed with this data. Then, while inputting one scan data, the data corresponding to one scan line already input is output.

As shown in FIG. 3, the coordinate calculation circuit 22 after processing calculates the coordinates of the result of enlarging / reducing rotation processing of the input coordinates of the already input scan data. Α (| sinθ | + | cosθ |) in the main scanning direction centered on the coordinates after the processing
Is the length of one side, and one side is β (| sinθ | + | cos
The grid points of the output image existing in the rectangular area having the length of θ |) are detected by the processed grid point detection circuit 24 in the area.
When the grid points detected by the in-area grid point detection circuit 24 are sequentially converted (inversely converted) by the coordinate conversion circuit 28, the coordinates of the grid points in the processed coordinate system when the coordinate axes themselves are rotated and independently scaled are obtained.
From this coordinate, the input pixel used for interpolation and the coefficient used for interpolation are obtained from the integer part and the decimal part, respectively. As a result, the value corresponding to the output grid point is obtained and output.

Next, the coordinate calculation circuit 22 after processing will be described with reference to FIG. The calculation of the above formula (1) is executed. Read sync signals 4-a, 4 used in the input scan data source 4
It operates in synchronization with -b and 4-c. Page sync signal 4-c
Thereby, the sub-scanning counter 41 is reset and -2 is loaded as the initial value. From the scan data source 4,
This is because the operation is delayed by two scanning lines. The main scanning counter 42 is reset by the sub-scanning synchronizing signal 4-a, and 0 is loaded as an initial value. In equation (1) above
x and y are the output of the main scanning counter 42 and the output of the sub-scanning counter 41, x _c and y _c are the main scanning offset (rotation) 43 and the sub-scanning offset (rotation) 44, respectively, and the coordinates of the center of rotation. Is. Also, depending on the rotation angle θ, sin θ, cos
θ and −sin θ are set as constants. By subtracting, multiplying, and adding these, the coordinates (x ', y') after the rotation processing are output. x ′ and y ′ are decimal numbers. Next, the main scanning offset (magnification) x _z , y ′ is subtracted from the sub scanning offset (magnification) y _z , and the results are respectively the main scanning direction scaling factor α and the sub scanning direction scaling factor β. By multiplying and adding x _z and y _z respectively, the coordinate x ″, y ″ after the processing of the rotation / independent variable magnification is obtained.

Next, the intra-region grid point detection circuit 24 will be described with reference to FIG. The lengths of one side in the main scanning direction and the sub-scanning direction centering on the processed coordinates are α (| cos θ | + | sin θ
|) And β (| cosθ | + | sinθ |) rectangles are set, and main scanning coordinates and sub-scanning of grid points (coordinate points in which both main scanning direction coordinates and sub-scanning direction coordinates are integers) within the rectangle are set. Output the coordinates. A value (integer part) obtained by cutting off the decimal part of the value obtained by adding α (| cosθ | + | sinθ |) / 2 to x ″ as the output value of the main scanning coordinates, and α (| cosθ | + | sinθ |) / Value obtained by subtracting 2 and adding 1 and then discarding the fractional part (integer part)
Is being output. Β in y ″ as the output value of the sub-scanning coordinates
(| Cosθ | + | sinθ |) / 2 is the value obtained by rounding down the decimal part (integer part), and β (| cosθ | + | sinθ |) / 2 is subtracted by 1 and the decimal is added The value (integer) with the part truncated is output. Each of the two sets of integer values is the coordinate on the x-axis and the coordinate on the y-axis of the grid point to be obtained. Figure 13a
A and B represent grid points specified by this output.

Coordinates (integers) of the grid points in the coordinate system in which the coordinate axes themselves are rotated / independently scaled are obtained by the coordinate conversion circuit shown in FIG. This is the coordinate calculation circuit 22 after the processing shown in FIG.
This is the reverse conversion of the processing of the.
Independent scaling is performed at 1 / α and sub-scanning direction scaling factor 1 / β, and rotation is performed by -θ.

Within the raster buffer 4 from the integer part of the inversely converted coordinates (decimal number) and the values of the integer part + 1 sub-scanning and main-scanning respectively.
Pixels (a, b, c, d in FIG. 13b) are obtained, interpolation coefficients (α, β in FIG. 13c) are determined from the decimal part, and the interpolation processing circuit shown in FIG. Then, the correction value is calculated and output. The circuit shown in FIG. 7 performs interpolation processing on all grid points existing in the above-mentioned virtual rectangular area of the coordinates after processing for one main scanning synchronous clock.

The maximum value (main scanning output 1) and the minimum value (main scanning output 2) of the coordinates in the main scanning direction of the grid points existing in the rectangular area given by the circuit shown in FIG. From the maximum value (sub-scan output 1) and the minimum value (sub-scan output 2), the coordinates of all grid points are set to the main scan operation synchronization of the clock faster than the main scanning synchronization and the sub-clock of the clock faster than the main scanning operation synchronization. The main scanning coordinates and the sub scanning coordinates of the grid points in the area are sequentially output in synchronization with the scanning operation synchronization. Main scanning operation synchronization is It operates at higher speeds. In the example, it operates at 4 times (Fig. 5c). Sub-scanning operation synchronization as well as main-scanning operation synchronization It operates at the above high speed (Fig. 5d). In the example the magnification is 1.6
Because it is double It suffices to operate at the above high speed. Counter 101 in FIG. 5b
Reference numerals 102 and 102 are one-shot down counters which output a high level during counting and output a low level when the count reaches zero. Also, in FIG.
3,104 is also a down counter. In the interpolation processing circuit of FIG. 7, the calculation of the equation (2) is first performed by (1-δ) V (a) +
Let δV (c) and (1-δ) V (b) + δV (d) be respectively δ {V (c) -V (a)} + V (a) = (1-δ) V
(A) + δV (c) = V ₁ δ {V (d) -V (b)} + V (b) = (1-δ) V
(B) + δV (d) = V ₂ and then ε (V ₂ −V ₁ ) + V ₁ = (1−ε) V ₁ + εV ₂ = (1−δ) (1−ε) V (a) + (1-δ) εV
(B) + δ (1-ε) V (c) + δεV (d) = V (D).

The post-processing area grid point calculation circuit 24 shown in FIG.
Although the coefficient K of the side length of the rectangle is set using the numbers | sinθ | and | cosθ | that are determined according to the rotation angle θ, as shown in Fig. 14, a constant that does not depend on the rotation angle θ is set. May be used. This eliminates the need to set | sinθ |, | cosθ | for θ, and the circuit scale can be reduced. In this case, the length of the side in the main scanning direction is The side length in the sub-scanning direction is Will be used.

<Effect> As described above, according to the present invention, the image represented by the input scanning data is subjected to the rotation processing and the scaling processing in the scanning direction and the vertical direction thereof at the magnifications α and β, respectively. At this time, a converted image of high quality can be obtained at high speed without requiring a memory for storing the input image data in frame units.

[Brief description of drawings]

1 is a basic configuration diagram of this embodiment, FIGS. 2a, 2b, and 2c are diagrams showing conventional defects, FIG. 3a is a block diagram of the first half of the circuit of the entire embodiment, and FIG. , Block diagram of the latter half of the same period, No. 4
The figure is a more detailed block diagram of the coordinate calculation circuit after the rotation shown in FIG. 3a, and FIGS. 5a and 5b are the more detailed block diagrams of the in-region lattice point detection circuit after the rotation / independent scaling in FIG. 3a. Figure, fifth
FIG. 5C is a signal relationship diagram of main scanning synchronization-main scanning operation synchronization, fifth
FIG. D is a signal relationship diagram of main scanning operation synchronization-sub scanning operation synchronization,
FIG. 6 is a more detailed block diagram of the coordinate conversion (inverse conversion) circuit of FIG. 3b, FIG. 7 is a more detailed block diagram of the interpolation processing circuit of FIG. 3c, and FIG. 8 is an image scanning. FIG. 9 is a diagram showing the state, FIG. 9 is a diagram showing the relationship between the page synchronization signal and the sub-scanning synchronization signal, FIG. 10 is a diagram showing the relationship between the sub-scanning synchronization signal and the main scanning synchronization signal, and FIG. Configuration diagram of raster memory, FIG. 11 b, c is a diagram showing the relationship between the raster memory and the scan data, FIG. 12 is a diagram showing the execution state of interpolation processing, 13
14a, 14b and 14c are views showing a method of obtaining interpolated output image data from input scan image data that is rotated and scaled independently, FIG.
The figure is a block diagram of a modification of FIG. 5a.

Claims (1)

[Claims] 1. A scan input means for inputting image data for each pixel as scan data in units of lines, and a rotation direction and a scan direction for an image represented by the scan data input by the scan input means. An image processing apparatus comprising: a processing unit that performs a scaling process in the vertical direction with magnifications α and β respectively; and an output unit that sequentially outputs image data processed by the processing unit, wherein the processing unit includes the scanning unit. Calculating means for calculating the position of the image data input by the input means after the rotation processing and the scaling processing, and a plurality of images before the rotation processing and the scaling processing for the data of the pixels in the vicinity of the position calculated by the calculating means. And an interpolating means 30 for interpolating based on the data, wherein the calculating means and the interpolating means further include calculation and interpolation in synchronization with the input of the image data by the scanning input means. To occupy perform the process, the scan input means, the image processing apparatus characterized by having a synchronous control means for supplying a predetermined synchronization signal to the calculation means and interpolation means.