JP2001222275A - Image mapping method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To calculate a coordinate of a source image to be mapped from a coordinate in a deformed and mapped four-sided figure and to realize mapping of a pixel along a straight line for a vanishing point in perspective drawing. SOLUTION: This method is constituted of a means for specifying the positions of four vertexes of the source image, a means for specifying two points A1, A2 on an X axis or a Y axis of a mapping coordinate system and an optional point A3 not existing on the same axis as the A1, A2 and a means for specifying two points B1, B2 on the same axis as the A1, A2 and an optional point B3 not existing on the same axis as the B1, B2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to an image mapping method.

2. Description of the Related Art A conventional image mapping method is performed by designating four vertices of a source image to be mapped indicated by a rectangular area and four vertices of a quadrangle to be mapped. In addition, the coordinates of the square to be mapped are calculated from the coordinates of the pixels of the source image by affine transformation in which parameters are determined at the vertices of the square to be mapped. Hereinafter, the details will be described with reference to FIG. 11a is a square to be mapped, and 11b is a source image to be mapped. The vertices a, b, c, and d of the source image correspond to the vertices a ', b', c ', and d' of the quadrangle to be mapped, respectively, and a and a 'are the origins of the respective coordinate systems. Since the width and height of the source image are represented by the coordinates (X, Y) of c, they are X and Y, respectively, and the coordinates of b ', c', d 'are respectively
(Bx, By), (Cx, Cy), (Dx, Dy). From these parameters, the coordinates (x ′, y ′) of the square pixel to be mapped are obtained by performing the affine transformation represented by Equation 1 on the coordinates (x, y) of the pixels of the source image.

(Equation 1)

However, according to the prior art described above, since the coordinates of the square to be mapped are calculated from the coordinates of the pixels of the source image, the size of the number of pixels to be mapped and the number of pixels to be mapped are small or large. Depending on the relationship, the same pixel may be mapped a plurality of times, or a pixel may not be mapped, in the rectangle to be mapped. Also, when pseudo 3D display is realized by 2D display, the linearity of each side of the quadrangle to be mapped is preserved, so that the mapped pixels deviate from the straight line for the vanishing point in perspective. That was an unnatural image. 8 × 8 in FIG.
Here is an example of mapping the source image of the square. 12a is X
It is a diagram showing a perspective method of equalizing the division interval on the axis and drawing a straight line to each vanishing point, 12b is a conventional mapping method of equalizing the division interval on each side and drawing a straight line to the opposite side. FIG. Therefore, an object of the present invention is to calculate coordinates of a source image to be mapped from coordinates in a rectangle to be mapped, and to realize mapping of pixels along a straight line to a vanishing point in perspective. .

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a rectangular or square area in a two-dimensional space formed by an X-axis and a Y-axis coordinate system. The mapped source image is mapped to all interior angles of 18
Means for designating the positions of four vertices of a source image in image mapping for mapping by transforming into a quadrangle smaller than 0 degrees, and an X axis or Y of a coordinate system to be mapped
The means for designating an arbitrary point A3 that is not on the same axis as the two points A1, A2 on the axis and the two points B1, B2 and B1, B2 on the same axis as A1, A2 Means for designating an arbitrary point B3 which is not on the same axis, wherein A1, A2,
A triangle P composed of A3 or a parallel line Q composed of straight lines L1 and L1 composed of A1 and A3 and a straight line L2 including A2, and a triangle R composed of B1, B2 and B3, or a triangle R composed of B1 and B3 B2 parallel to straight lines L3 and L3
A parallel line S or B1 composed of a straight line L4 including
And a parallel line T formed by crossing a straight line L5 composed of B2 and a parallel line T composed of a straight line L6 parallel to L5 and including B3. Is an image mapping method for calculating the coordinates of the pixels of the source image to be mapped from the coordinates of the pixels. According to a second aspect of the present invention, in the image mapping method according to the first aspect, when the elements to be intersected to form the quadrangle U are triangles, the specified points A3 and B3 are triangles each having a vertex. Within this, mapping of the source image is performed so as to be a vanishing point in perspective.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1, 2, 3, 4, 5, 6, 7, 8, and 9. FIG. FIG. 1 is an explanatory diagram showing a state in which a triangle U is formed by intersecting a triangle P and a triangle R, and a source image is mapped onto the square U. 1a shows the relationship between the quadrangle U to be mapped and the designated coordinates, and 1b shows the source image to be mapped. The vertices a, b, c, d of the source image correspond to the vertices a ', b', c ', d' of the square U, respectively. FIG. 2 is an explanatory diagram showing a state in which a rectangle U is formed by intersecting a triangle P and a parallel line S, and a source image is mapped onto the rectangle U. 2a shows the relationship between the rectangle U to be mapped and the designated coordinates, and 2b shows the source image to be mapped. The vertices a, b, c, d of the source image correspond to the vertices a ', b', c ', d' of the square U, respectively. FIG. 3 is an explanatory diagram showing a state in which a parallel line Q and a triangle R intersect to form a square U, and a source image is mapped to the square U. 3a shows the relationship between the quadrangle U to be mapped and the designated coordinates, and 3b shows the source image to be mapped. The vertices a, b, c, d of the source image are the vertices a ',
b ', c', and d ', respectively. Figure 4 shows the parallel line Q
FIG. 4 is an explanatory diagram showing a state in which a square U is formed by intersecting parallel lines S with each other and a source image is mapped to the square U. 4a shows the relationship between the rectangle U to be mapped and the designated coordinates, and 4b shows the source image to be mapped.
The vertices a, b, c, d of the source image are the vertices a ', b',
They correspond to c 'and d', respectively. FIG. 5 is an explanatory diagram showing a state in which a rectangle U is formed by intersecting a triangle P and a parallel line T, and a source image is mapped to the rectangle U. 5a
Indicates the relationship between the square U to be mapped and the specified coordinates, and 5b indicates the source image to be mapped. The vertices a, b, c, d of the source image are the vertices a ', b', c ', d' of the square U
Respectively. FIG. 6 is an explanatory diagram showing a state in which a parallel line Q and a parallel line T intersect to form a rectangle U, and a source image is mapped to the rectangle U. 6a shows the relationship between the rectangle U to be mapped and the coordinates to be specified, and 6b
Indicates a source image to be mapped. The vertices a, b, c, d of the source image correspond to the vertices a ', b', c ', d' of the square U, respectively. FIG. 7 is an explanatory diagram showing a detailed coordinate calculation in the example of the mapping shown in FIG. FIG. 8 is an explanatory diagram showing a detailed coordinate calculation in the mapping example shown in FIG. FIG. 9 is an explanatory diagram showing a detailed coordinate calculation in the example of the mapping shown in FIG. Hereinafter, a detailed coordinate calculation in the example of the mapping shown in FIG. 1 will be described with reference to FIG. 7b (x,
The coordinates of the pixels of the source image indicated by (y) are represented by (x'.y ') of 7a.
When mapping to (x'.y ') parallel to the X axis
On the scan line SL including the distance X 'between the intersection with the straight line A2-A3 and the intersection with the straight line A1-A3, the distance px between the intersection with the straight line A2-A3 and (x', y '), Intersection with line B1-B3 and line B2
-The distance Y 'to the intersection with B3, the intersection with the straight line B1-B3 and (x',
y ′) and the distance py is calculated by Equations 2, 3, 4, and 5,
The coordinates (x, y) of the pixels of the source image may be obtained by performing the operation shown in Expression 6 with X, Y, which is the size of the source image.

(Equation 2)

(Equation 3)

(Equation 4)

(Equation 5)

(Equation 6) In Equations 2 and 3, 0 ≦ y ′ ≦ A3y In Equations 4 and 5, 0
.Ltoreq.y'.ltoreq.B3y In Equation 6, since 0.ltoreq.Px.ltoreq.X 'and 0.ltoreq.Py.ltoreq.Y', linear interpolation can be performed for the multiplication / division unit. Further, a detailed coordinate calculation in the example of the mapping shown in FIG. 2 will be described below with reference to FIG. When mapping the coordinates of the pixel of the source image represented by (x, y) of 8b to (x′.y ′) of 8a, X ′, p is calculated by Expressions 2, 3, and 5.
The coordinates (x, y) of the pixels of the source image may be obtained by calculating x 'and py's by Y' using Equation 7, and performing the operation shown by Equation 6 with X and Y which are the size of the source image.

(Equation 7) Further, the details of the coordinate calculation in the example of the mapping shown in FIG. 5 will be described below with reference to FIG. When mapping the coordinates of the pixel of the source image indicated by (x, y) of 9b to (x'.y ') of 9a, X ′ is calculated by Expressions 2 and 3, and X ′ is calculated by Expressions 8 and 9, The coordinates (x, y) of the pixels of the source image may be obtained by calculating Y ′ and py and performing the operation shown in Expression 6 with X and Y that are the sizes of the source image. At this time, B1x, B2x, B
3x is not used for the operation.

(Equation 8)

(Equation 9) As described above, depending on whether the elements that intersect to form the quadrangle U are the triangles P, R or the parallel lines Q, S, or the parallel lines T,
Change the calculation to find X ', Y' and px, py,
The above operation is performed on the coordinates of all the pixels in the coordinates of the source image in all the cases of FIGS. 1 to 6.
(x, y) can be obtained. "Effects of Embodiment" In this embodiment, since the coordinates of the source image to be mapped are calculated from the coordinates in the rectangle to be mapped, regardless of the magnitude relationship between the number of pixels to be mapped and the number of pixels to be mapped. In the rectangle to be mapped, the same pixel is not mapped a plurality of times, and there is no pixel that is not mapped. Further, if the elements to be intersected to form the quadrangle U are triangular, any point A
In 3 and B3, the source images are mapped so as to be vanishing points in perspective within triangles each having a vertex. Therefore, when 3D display is pseudo-realized by 2D display, mapping is performed. Pixels match the straight line for the vanishing point in the perspective view, and a natural image can be obtained. In addition, the number of multiplication operations is smaller than that of the conventional mapping method, and the interpolation operation can be used for multiplication and division, so that the amount of calculation for mapping can be reduced. "Other embodiments" In the above embodiment, A1, A2, B
Although 1, B2 is designated on the X axis, it may be designated as the Y axis. Although A1 and B1 are specified as parameters, they may be fixed at the origin (0, 0) of the XY axes and specified to reduce the parameters. Although the side of the area of the source image to be mapped is parallel to the X axis or the Y axis, it may be oblique. In FIG. 10, the sides are XY axes and 4
5 shows an example of a square source image region forming an angle of 5 degrees. The coordinates (x, y) of the pixel of the source image in the region indicated by 10a obtained in the above embodiment are calculated by the formula (10), and (xr, yr) is used as the coordinates of the pixel of the new source image.
Are obtained as shown in FIG.

(Equation 10)

As described above, according to the present invention, since the coordinates of the source image to be mapped are calculated from the coordinates in the rectangle to be mapped, the number of pixels to be mapped and the number of pixels to be mapped are reduced. Regardless of the magnitude relationship of, there is no possibility that mapping is performed a plurality of times on the same pixel within a rectangle to be mapped, or that a pixel is not mapped. In addition, square U
If the elements to be intersected to form a triangle are
The arbitrary points A3 and B3 to be specified are mapped in the source image so as to be vanishing points in perspective within triangles each having a vertex.
In the case of realizing the D display, the mapped pixels coincide with the straight line for the vanishing point in the perspective view, and a natural image can be obtained. In addition, the number of multiplication operations is smaller than that of the conventional mapping method, and the interpolation operation can be used for multiplication and division, so that the amount of calculation for mapping can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram when a triangle P and a triangle R intersect according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a case where a triangle P and a parallel line S intersect according to one embodiment of the present invention.

FIG. 3 is an explanatory diagram of a case where a parallel line Q and a triangle R intersect according to one embodiment of the present invention.

FIG. 4 is an explanatory diagram when a parallel line Q and a parallel line S intersect in one embodiment of the present invention.

FIG. 5 is an explanatory diagram of a case where a triangle P and a parallel line T intersect according to one embodiment of the present invention.

FIG. 6 is an explanatory diagram when a parallel line Q and a parallel line T intersect in one embodiment of the present invention.

FIG. 7 is a detailed explanatory diagram of the mapping in FIG. 1 according to the embodiment of the present invention;

FIG. 8 is a detailed explanatory diagram of the mapping in FIG. 2 according to the embodiment of the present invention;

FIG. 9 is a detailed explanatory diagram of the mapping in FIG. 5 according to the embodiment of the present invention;

FIG. 10 is an explanatory diagram in a case where a side of a region of a source image is oblique according to one embodiment of the present invention;

FIG. 11 is an explanatory diagram showing a conventional mapping method.

FIG. 12 is an explanatory diagram showing a difference between an embodiment of the present invention and a conventional mapping method.

[Explanation of symbols]

1a Relationship between rectangle U to be mapped and designated coordinates 1b Source image area to be mapped 2a Relationship between rectangle U to be mapped and designated coordinates 2b Source image area to be mapped 3a Relationship between rectangle U to be mapped and designated coordinates 3b Source image area 4a Relationship between rectangle U to be mapped and designated coordinates 4b Source image area to be mapped 5a Relationship between rectangle U to be mapped and designated coordinates 5b Source image area to be mapped 6a Square U to be mapped and coordinates to be designated Relationship 6b Source image area to be mapped 7a Details of relationship between square U to be mapped and specified coordinates 7b Details of source image area to be mapped 8a Details of relationship between square U to be mapped and specified coordinates 8b Source image area to be mapped Details 9a Square U to map 9b Details of the source image area to be mapped 10a Source image area where the side is mapped parallel to the XY axis 10b Source image area 11a where the side forms an angle of 45 degrees with the XY axis Relationship between rectangle to be mapped and coordinate to be specified by conventional mapping method 11b Source image area to be mapped by conventional mapping method 12a Example of mapping by perspective method 12b Example of mapping by conventional mapping method

Claims (2)

[Claims] 1. A source image to be mapped, which is represented by a rectangular or square area, is transformed into a quadrangle having all interior angles smaller than 180 degrees in a two-dimensional space composed of an X-axis and a Y-axis coordinate system. Means for specifying the positions of the four vertices of the source image, and two points A1, A2 and A1, A2 on the X-axis or Y-axis of the coordinate system to be mapped are on the same axis. Means for designating an arbitrary point A3 that does not have, and means for designating an arbitrary point B3 that is not on the same axis as two points B1, B2 and B1, B2 on the same axis as A1 and A2, A triangle P composed of A1, A2, and A3 or a straight line L1 and L composed of A1 and A3
1 and a straight line L2 parallel to A2 and including A2.
And a triangle R consisting of B1, B2, and B3 or B1
A parallel line S composed of straight lines L3 and L3 composed of straight lines L3 and L3 and a straight line L4 including B2, or a parallel line composed of straight lines L5 and L5 composed of B1 and B2 and a straight line L6 parallel to and including B3. An image mapping method for calculating the coordinates of the pixels of the source image to be mapped from the coordinates of the pixels in the rectangle U, characterized by mapping the source image to a rectangle U formed by intersecting T and T. 2. An image mapping method according to claim 1, wherein if the elements to be intersected to form the quadrangle U are triangles, the specified points A3 and B3 are within the triangle each having a vertex. The source image is mapped so that it becomes a vanishing point in the law.