JPS6256073A - Image processing method - Google Patents

Abstract

PURPOSE:To perform a process to rotate a scanning input image data one after another synchronizing with a scanning and synchronizing signal and to attain an output without the omission and the dislocation of an image by allocating a rotation processed data to a virtual coordinate corresponding to a virtual pitch. CONSTITUTION:Against a scanning data already inputted, a coordinate resulting from the rotation process of the inputting coordinate is calculated at a coordinate calculation circuit after rotated. The lattice point of an output image existing within a square area, the side of which has a length of sintheta+costheta centering the coordinate after the rotation is detected at a within area lattice point detecting circuit. The coordinate in a coordinate system after the rotation of the lattice point when the coordinate axis itself of the lattice point detected at the within area lattice point detecting circuit is rotated at an in-order- coordinate conversion (inverse conversion) circuit is calculated. By calculating each of the inputting picture element and a factor to use for an interpolation by the coordinate respectively from its integer part and decimal part, a value corresponding to an output lattice point is calculated and outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image processing method for rotating a scanned digital image while suppressing image deterioration caused by image skipping and misalignment.

Conventionally, many devices that rotate digital images execute the process after input image data is once loaded into a memory. However, the amount of information in the input image is generally greater than the amount of information in the processed image data, and storing the input image information requires a larger amount of memory capacity than storing the processed image information. Image information -
The method of importing the data into the H memory is disadvantageous in terms of the cost and circuit scale required for the memory, compared to the method of processing the data in synchronization with the input scanning synchronization signal and sequentially outputting the processed data to the output memory.

On the other hand, in a process in which scanning input image data is sequentially rotated in synchronization with a scanning synchronization signal, the processed data does not match the pitch of the output, resulting in image omission or deviation, resulting in the deterioration of one image. It had some drawbacks. An example is shown in Figure 1. FIG. 1(a) shows the pitch of the original image, the broken line in FIG. 1(b) shows the pitch of the output, and the solid line shows the pitch of the image obtained by rotating the original image by 55 degrees. Each square represents a pixel, and each output pixel (dashed line square) is the pitch of the output.The center of the pixel in the rotated image is associated with that pixel. This indicates that the pixel is a blank pixel (pixel with no associated image data).

The present invention eliminates the drawbacks of the conventional example described above, performs processing to sequentially rotate scanning input image data in synchronization with a scanning synchronization signal, and makes it possible to obtain output without image omission or deviation. did.

Fig. 2 to Fig. 11 are examples of the present invention, and Fig. 2=1 shows the embodiment of the present invention.
This is the first half of the block diagram of the entire circuit of the embodiment, and is part 2-2.
The figure is from the second half of the same year. Figure 3 is a more detailed block diagram of the coordinate detection circuit after rotation in Figure 2-1, and Figure 4 is a more detailed block diagram of the coordinate detection circuit after rotation in Figure 2-1.
FIG. 5 is a more detailed block diagram of the coordinate transformation (inverse transformation) circuit of FIG. 2-2, and FIG. FIG. 3 is a more detailed block diagram of the interpolation processing circuit of FIG. 2; FIG. 7 shows the state of image scanning. FIG. 8 is a schematic configuration diagram of the embodiment.

FIG. 9 shows the relationship between the page synchronization signal and the sub-scanning synchronization signal. FIG. 10 shows the relationship between the sub-scanning synchronization signal and the main-scanning synchronization signal. FIG. ii shows the structure of the raster memory and its relationship with scan data. 12th
FIG. 13 shows the state of execution of interpolation processing. FIG. 13 illustrates a method for obtaining interpolated output image data from rotated input shoe image data.

Considering the main scanning direction of the original image as the X-axis direction and the sub-scanning direction as the y-axis direction, the main scanning synchronization corresponds to the coordinates 1, 2, 3° -- m -- in the X-axis direction, with the sub-scanning synchronization signal as the base point. Attach. Furthermore, the coordinates 1, 2, 3, etc. in the y-axis direction are associated with the sub-scanning synchronization based on the page synchronization signal. That is, (Xo, yo) corresponds to the XoF soto of the Vo-th raster of the original picture (Figs. 7, 9, 1O
figure).

Let the point at the coordinates (x, y) in Cartesian coordinates be (xc,
The coordinates rotated by θ with the point of yc) as the center of rotation are (
x′, y′), then (x”, y′) and
(x, y).

The relationship between (xc, yc) and θ can be expressed as follows.

Figures 11-b and 11-0 illustrate the input scanned image and the rotated scanned image.

Figure 11-b is the original image, Figure 11-0 is the rotated image,
The X mark is the center of rotation.

By the way, Cos θ and 5ino in equation (1) are generally irrational numbers, so even if X, V, XC, and yO are natural numbers, x' and y' are irrational numbers. In other words, the scanned image after rotation processing is at a position shifted from the pixel (dot) position associated with the input/output synchronization signal.

The value of each pixel of the image after the rotation process is determined using three consecutive raster data.

Assume a square with a length of 5 ino + cos θ on one side centered on the center of the pixel of interest in the two-headed raster (center raster) of the three consecutive rasters, and the output pixel centered within this square. To detect. The circle mark in Figure 13-a (
A, B, C, D) indicate detected pixels.

The value can be determined using the data of the four rotated rasters surrounding these A, B, C, and 04 images 111. A case where attention is paid to A is shown in Fig. 13-b. a, b, c surrounding A.

The value of A is determined from the values of the four pixels of d.

Figure 13-0 shows the method for determining this. When a perpendicular line is drawn from the center of pixel A to the line segment connecting the center of pixel a and the center of pixel C, the ratio at which the line segment is internally divided by the foot is α:l−α. When a perpendicular line is drawn from the center of pixel A to the line segment connecting the center of pixel a and the center of pixel A, the ratio of the line segment internally divided by that foot is β: 1
−β. The values of pixels a, b, c, and d are respectively V
(a), V (b), V (c), V (d)
When the threshold value V(A) of pixel A is set to V (
A) −(1−α) (1−/3) V (a) + (1−
a), 8V (b)+cx (1-73) V (c)
+aβv (co −−−−−−−−−−−(2)
shall be. Similarly, for pixels B, C, and D,
B) , V (C), , V (D) can be found.

Next, the operation of the embodiment will be explained based on a configuration example for realizing one method.

When the operator issues a rotation instruction using the operation instruction device, the operation instruction device sets information corresponding to the instructed rotation angle in the processing circuit.

When the operator issues a start-up instruction, the operation instruction device starts up the synchronous control device, and the synchronous control device outputs a synchronization signal to the scanning data source and processing circuit, causing the device to execute the operation (Fig. 8). ).

The image data is scanned as shown in Figure 7, and the falling edge of the page synchronization signal specifies the beginning of the leavevage image, and the leading edge of the sub-scanning synchronization signal specifies the beginning of the data in each scanning line within the page. is specified. The falling edge of the main scanning synchronization signal specifies the timing of data capture for each pixel (FIGS. 9 and 10).

The execution of rotation/interpolation will be explained below.

According to the rotation angle θ instructed by the operator, sin θ,
-5inθ and COSθ are both used as a coordinate detection circuit and a coordinate transformation (inverse transformation) circuit after rotation.

Each of 1 sin θl and 1 cos θ1 is set in the area grid point detection circuit after rotation by a CPU (not shown). Also, depending on the rotation center specified by the operator,
The main scanning offset and the sub-scanning offset are both set in a post-rotation coordinate calculation circuit and a coordinate conversion (inverse conversion) circuit by a CPU (not shown).

The scanning data source outputs the image data as scanning data to the Rask memory in accordance with the synchronization signal output by the synchronization control device. Figure 11-a shows the configuration of the rask memory,
Of the four rask memories corresponding to the scanning lines of the four trees, one takes in image data from a scanning data source and the other three trees use this data as input data to execute rotation and interpolation processing. And one run while inputting one tree of scan data! F: Output data corresponding to the line.

As shown in Figure 2, for the scan data that has already been input,
A post-rotation coordinate calculation circuit calculates the coordinates resulting from rotation processing of the input coordinates. A lattice point detection circuit in the rotated area detects lattice points of the output image existing in a square area whose one side has a length of sin θ→−CO5θ centered on the rotated coordinates. When the coordinate axes of the lattice points detected by the intra-area lattice point detection circuit are sequentially rotated by the coordinate transformation (inverse transformation) circuit, the coordinates of the lattice points in the rotated coordinate system are determined.

From these coordinates, the input pixel used for interpolation and the coefficient used for interpolation are determined from the integer part and decimal part, respectively. Thereby, the value corresponding to the output grid point is determined and output.

Next, the coordinate calculation circuit after rotation will be explained with reference to FIG. This is to execute the calculation of the above-mentioned equation (1). It operates in synchronization with the synchronization signal used for the input scanning data source. The sub-scanning counter is reset by the page synchronization signal and -2 is loaded as an initial value. This is because it operates with a delay of two scanning lines from the scanning data source. The main scanning counter is reset by the sub-scanning synchronization signal, and O is loaded as an initial value. In the above equation (1), x and y are the output of the main scanning counter and the output of the sub-scanning counter, respectively, and Xc and Vc are the main scanning offset and sub-scanning offset, respectively, and are the coordinates of the center of rotation. Also, depending on the rotation angle θ, sin θ.

cost and −5inθ are set as constants. By subtracting, multiplying by nine, and adding these, the rotated coordinates (x', y') are output.

x'' and y' are decimal numbers.

The circuit for calculating grid points in the rotated area will be explained according to FIG.
The length of one side centered on the rotated coordinates is l cosθl
Consider a square with +1 sin θ1 and output the main scanning coordinates and sub-scanning coordinates of grid points (coordinate points whose main scanning direction coordinates and sub-scanning direction coordinates are both integers) within the square (square in Figure 13-a) The value (integer part) obtained by adding (lcos(Jl+1sinθ1)/2) to x', y', respectively, and rounding down the decimal part (integer part), and (teasθ
The value (integer part) obtained by subtracting l+1sinθ1)/2 and adding the decimal part is output. Chapter 13-a
A, B, C, D in the diagram.

The coordinates (integers) of the grid points are determined by a coordinate conversion circuit shown in FIG. 5 in a coordinate system in which the coordinate axes are rotated. This is an inverse transformation of the coordinate calculation after rotation in FIG. 3 (rotation by -0).

4 in the raster buffer from the integer part of the inversely transformed coordinates (decimal number) and the respective values of the sub-scan and main scan of the integer part + 1.
Pixel (a in Figure 13-b).

b, c, d,) and calculate the interpolation coefficient (13th-
α, β in FIG. The circuit in FIG. 6 has the following characteristics for the main scanning synchronous l clock
FIG. 12 shows how a scanning point moves with a main scanning clock that sequentially outputs correction values for four grid points (actually, they may be the same grid point).

Interpolation for four pixels is performed for one image period signal in synchronization with the main scanning synchronization signal, but the main scanning output 1, which is the output of the post-rotation area grid point calculation circuit in Figure 2-1 or Figure 4, is The main scanning output 2 may have the same value, and the sub-scanning output l and the sub-scanning output 2 may also have the same value. If they are all different, processing will be performed on different output pixels for all four pixels, and if either main scanning or sub-scanning has the same value, processing will be performed on the same output pixels for each two pixels, so interpolation for two output pixels for urban people. It will be processed.

If both the main scanning and sub-scanning have the same value, interpolation processing will be performed for all four pixels in the same output direction. This corresponds to the case where there are four output pixels within a certain square, two output pixels within a certain square, and one output pixel within a certain square, as shown in FIG. 12-2. In the interpolation processing circuit shown in FIG. 6, the calculation of equation (2) is first performed by (1-a) V
(a)+αV (c) and (1-a)V
(b) +av (d) respectively a (V (c) −V (a) ) +V (a)=
(1-(X) V (a) +aV (c) =
Vta (V (d) −V (b) ) +V
(b) = (1-(E) V (b) +aV (d
) = V2, then β(V2-Vl) +Vt = (1-β)v1+β■2 = (1-α)(1-β) V (a) + (1-c
t)βv (b)+α(1-β) V (C)+αβV
It is calculated as (d)=V(A).

As explained above, the effect is to enable rotation processing of sequentially scanned digital images while synchronizing with scan synchronization, without requiring memory on the input side, and suppressing image deterioration caused by image skipping and misalignment. be.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional problem. Figure 2-1 shows
This is the first half of the block diagram of the entire circuit of the embodiment, and FIG. 2-2 is the second half. Figure 3 is a more detailed block diagram of the coordinate detection circuit after rotation in Figure 2-1, and Figure 4 is a more detailed block diagram of the coordinate detection circuit after rotation in Figure 2-1.
FIG. 5 is a more detailed block diagram of the coordinate transformation (inverse transformation) circuit of FIG. 2-2, and FIG. FIG. 3 is a block diagram of a more detailed version of the interpolation processing circuit shown in the figure (no changes have been made to the contents); FIG. 7 is a diagram showing the scanning state of the image;
FIG. 8 is a schematic configuration diagram of the embodiment, FIG. 9 is a diagram showing the relationship between the page synchronization signal and the sub-scanning synchronization signal, and FIG. 10 is a diagram showing the relationship between the sub-scanning synchronization signal and the main scanning synchronization signal. , 11th
FIG. 1 to FIG. 11-3 are diagrams showing the configuration of a raster memory and its relationship with scan data. 12-1 and 12-2 are diagrams showing the execution state of interpolation processing, and 13-1
Figures 13-3 illustrate a method for obtaining interpolated output image data from rotated input scanned image data. ¥17-1@1 11th-? 4,11-3 Figure 5 Date of amendment order (shipment date) Procedural amendment form) % form % 1. Indication of the case 1985 Patent Application No. 196186 2. Name of the invention Image processing method 3. Make the amendment Patent applicant address 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (100
)Representative of Canon Co., Ltd. Noh Kaku 3 Department 4, Agent address: 3-30-26 Shimomaruko, Ota-ku, Tokyo 146, Specification subject to amendment Contents of amendment to Form 76

Claims (1)

[Claims] A pitch finer than the sampling pitch of the output image is assumed, the rotated data is assigned to virtual coordinates corresponding to the virtual pitch, and the processed data on the virtual coordinates corresponds to the sampling pitch of the output. An image processing method for sequentially processing scan input images in synchronization with a scan synchronization signal, the method comprising determining a value to be output to each address in an address space.