JPH07200816A - Image drawing method and apparatus - Google Patents

Abstract

(57) [Summary] [Purpose] Draw images expressing depth of field at high speed. [Configuration] In an image in which an object 5, an object 6, and an object 7 are displayed, a pixel region 10 having a small degree of defocus has a small sampling rate and a pixel having a large degree of defocus in order to accurately calculate a luminance value. In the area 12, the sampling rate is set large and the luminance value of the sampling pixel is calculated. In this way, the sampling rate is set according to the degree of defocus, only the brightness of the sampled pixels is calculated by distributed ray tracing, and the brightness value of the pixels between the sampling pixels is obtained by linear interpolation. The brightness calculation time of the defocus area is significantly reduced without deteriorating the image quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image drawing method and an apparatus therefor, and more particularly to an image drawing method and an apparatus therefor for drawing an image expressing a depth of field assuming a predetermined lens characteristic. .

[0002]

2. Description of the Related Art A camera model adopted in a general computer graphics (hereinafter referred to as CG) is a pinhole camera model. The image generated by this pinhole camera model is an image in focus in all parts of the image. However, the naked eye and a normal camera have an effective lens aperture, and a focused area is a field having a finite depth. Some objects appear to be in focus, while other objects are called out-of-focus images that represent the depth of field.
In order to express an image with a sense of reality, it is necessary to generate an image expressing the depth of field. In recent years, CG, which requires high-quality images such as photographs, is required to have a special effect such as the depth of field. Especially, landscape simulations and movies used for various presentations. Such a technique is actually being used in the CG used in the CG.

As a conventional CG technique for expressing the depth of field, a post-process method (Potmesil, "A LENS AND APERTURE CAMERA MODEL FOR S" for image processing after image generation is used.
YNTHETIC IMAGE GENERATION ", Computer Graphics 81)
Alternatively, the method required to calculate the depth of field during image generation can be performed simultaneously (Robert L. Cook, "Distributed Ray Tracin
g ", Computer Graphics 84) has been proposed.

[0004]

However, in order to express the depth of field in CG, both of the above two methods have a very large calculation load, and if the sufficient image quality is to be obtained, the depth of field is reduced. There is a problem that the image drawing time is ten or more times longer than that in the case of not expressing. More specifically, in order to express the depth of field in CG, an appropriate filter is adopted for all the pixels in the image area in the out-of-focus state, and convolution integration is performed with a large number of pixels centering on the target pixel. Therefore, the amount of calculation is generally enormous, and the image drawing time is extremely long.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and suppresses substantial deterioration of image quality, and an image drawing method for drawing an image expressing the depth of field at high speed. The purpose is to provide the device.

[0006]

In order to achieve the above object, an image drawing method according to claim 1 is an image drawing method for drawing an image expressing a depth of field on the assumption of a predetermined lens characteristic. Then, based on the predetermined lens characteristic and the depth value of the pixel, it is determined whether the pixel is in the focused state or the defocused state, and in response to the determination that the pixel is in the focused state, all the pixels are determined. The pixel is sampled by determining the sampling rate so that sampling is performed, the brightness value of the sampling pixel is calculated by the pinhole camera model and drawn, and the defocusing is performed in response to the determination that the defocusing state is set. Is calculated, the pixel sampling rate is determined based on the calculated defocus degree, and the determined sampling rate is determined. Sampling pixels based on the rate, filtering the pixels in the scattering circle corresponding to the sampling pixel to calculate the luminance value of the sampling pixel, calculating the luminance value of the pixel between the sampling pixels by a predetermined interpolation method, and sampling The pixel and the interpolated pixel are drawn based on the respective brightness values.

According to another aspect of the image drawing apparatus for achieving the above object, a focus determining unit determines whether a pixel is in a focused state or a defocused state based on a predetermined lens characteristic and a depth value of the pixel. In response to the / defocus determination means and the focus / defocus determination means determining that the pixel is in focus, the sampling rate is determined so that all pixels are sampled, and the pixels are determined based on the sampling rate. In response to the sampling means for sampling, the focus pixel drawing means for calculating and drawing the brightness value of the sampled pixel by the pinhole camera model, and the focus / defocus judging means judging that the defocus state is set. Defocus degree to calculate the degree of defocus Means out to determine the sampling rate of the pixels based on the degree of the calculated defocus,
Sampling means for sampling pixels based on the sampling rate, sampling pixel brightness calculating means for calculating the brightness value of the sampling pixel by filtering the pixels in the scattering circle corresponding to the sampled pixel, and between the sampling pixels It has an interpolated pixel brightness calculation means for calculating the brightness value of the pixel by a predetermined interpolation method, and a defocus pixel drawing means for drawing the sampling pixel and the interpolated pixel based on the respective brightness values.

[0008]

According to the image drawing method of claim 1, when it is determined that the pixel is in the defocused state, the degree of defocusing is calculated, and the sampling rate of the pixel is determined based on the calculated degree of defocusing. When the degree of defocus is large, the brightness value of the sampling pixel is calculated by determining and sampling the pixel based on the determined sampling rate and filtering the pixels in the scattering circle corresponding to the sampling pixel. Since it is meaningless to accurately calculate the pixel brightness due to the nature of the image, increase the sampling rate to reduce the number of filtering operations that require calculation time.If the degree of defocus is small, Due to the nature of, some accuracy is required, so reduce the sampling rate to improve image quality. Possible to calculate the luminance of the relatively high precision pixel without reducing the time. Then, the brightness value of the pixel between the sampled pixels is calculated by the interpolation calculation that can reduce the calculation time, and thus the drawing speed of the defocus area in the image can be significantly improved. Therefore, by suppressing the substantial deterioration of image quality,
An image expressing the depth of field can be drawn at high speed.

According to another aspect of the image drawing apparatus, the focus / defocus determining means determines whether the pixel is in the focused state or the defocused state based on the predetermined lens characteristic and the depth value of the pixel. In response to the focus / defocus determining means determining that the pixel is in focus, the sampling means sets the sampling rate so that all pixels are sampled, and the focus pixel drawing means determines the sampling rate based on the sampling rate. The brightness value of the pixel in focus is calculated by the pinhole camera model and drawn. By these processes, it is possible to draw with an accurate luminance value without degrading the image quality in the focus area in the image.

Further, in response to the focus / defocus determining means determining that the focus is defocused,
The defocus degree calculation unit calculates the degree of defocus, the sampling unit determines the sampling rate of the pixel based on the calculated degree of defocus, and samples the pixel based on the sampling rate. Then, the sampling pixel brightness calculation means calculates the brightness value of the sampling pixel by filtering the pixels in the scattering circle corresponding to the sampled pixel, and the interpolation pixel brightness calculation means calculates the brightness value of the pixel between the sampling pixels. It is calculated by a predetermined interpolation method, and the defocus pixel drawing means draws the sampling pixel and the interpolation pixel based on the respective brightness values. By these processes, when the degree of defocus is large, the sampling rate is increased to reduce the number of filtering operations that require calculation time, and when the degree of defocus is small, the sampling rate is reduced to improve the image quality. It is possible to calculate the luminance of the pixel with relatively high precision without dropping it extremely. In addition, the brightness value of the pixels between the sampled pixels is calculated by the interpolation calculation that can reduce the calculation time, so that the drawing speed of the defocus area in the image can be significantly improved. Therefore, it is possible to draw an image expressing the depth of field at high speed while suppressing a substantial decrease in image quality.

[0011]

Embodiments will be described in detail below with reference to the accompanying drawings showing embodiments. 1 and 2 are flow charts showing an embodiment of the image drawing method of the present invention. First, in step SP1, graphic data including a depth value (z value) is obtained, and in step SP2, predetermined graphic processing such as coordinate conversion considering the viewpoint position and light source position setting is performed, and the lens characteristics adopted in step SP3 are set. Set, select the pixel in the image in step SP4, and
It is determined whether the pixel selected in P5 is a focused pixel or a defocused pixel. If it is determined in step SP5 that the pixel is in focus, a sampling rate for sampling all the pixels is set in step SP6, and the brightness value of the pixel is determined by the pinhole camera model in step SP7 according to the sampling rate. It is calculated and drawn based on the ray tracing method.

On the other hand, when it is determined in step SP5 that the pixel is in the defocused state, as shown in FIG. 2, the scattering circle radius of the pixel is calculated in step SP8, and the scattering circle radius calculated in step SP9. Sampling rate is determined based on step SP1
At 0, the pixel is sampled at the sampling rate, and the brightness value of the sampled pixel is calculated by convolution integration using a predetermined filter at step SP11. At step SP12, the brightness value of the pixel between the sampling pixels is calculated by linear interpolation. , Drawing is performed based on the respective luminance values of the pixel sampled and the interpolated pixel in step SP13. When the processing in step SP7 or step SP13 is completed, it is determined whether or not the pixel selected in step SP14 is the last pixel in the image. If it is determined that the pixel is not the last pixel, the pixel is determined in step SP15. Is incremented by 1, and the pixel selection processing in step SP4 is performed. On the other hand, if it is determined in step SP14 that the selected pixel is the last pixel, then the series of processes ends.

The image drawing method of this embodiment will be described in more detail. An image that considers the depth of field is an image in which some objects appear to be in focus but other objects are out of focus.This phenomenon is not due to an optical function, but is recognized by the naked eye. It is caused by the function of the medium in which the image is shown. FIG. 3 is a diagram for explaining the depth of field. The surface 2 having the smallest diameter (MN) at the position U from the lens 1 that can be discriminated by the naked eye (that is, the point if the diameter is a little larger than this diameter). Is observed as an area, not an area), and shows the optical system in which the position of this surface 2 is in focus. L
D is an effective lens diameter defined as a value (F / n) obtained by dividing the focal length F by the lens aperture n. Point A on optical axis 3
Even if the surface 2 is moved in the range from to the point B, its diameter is smaller than MN, so that an object in this range is in focus and the point group can be recognized as a point group. The distance from the point A to the point B is called the depth of field (depth of focus), the range from the point A to the point B is called the focus range, and the other range is called the defocus range. From the proportional relationship in FIG. 3, the focusing distance U ₋ on the side closest to the lens 1 and the focusing distance U ₊ on the side farthest from the lens 1 are respectively expressed by the following equations.

[0014]

[Equation 1]

However, X is the minimum diameter that can be discriminated.

[0016]

[Equation 2]

Now, let us consider what size of a circle appears when the point is out of the focused range. FIG. 4 shows an optical system in which a point E at a distance P from the lens 1 is in focus and a distance from the lens 1 to an image plane I corresponding to the point E is Vp. In this state, the image at the distance Vp is a focused image. However, if the distance G to the lens 1 at the point G farther than the focal length P is D, the far point G is focused on the image plane H at the distance Vd. Therefore,
Objects on the distance D are projected as a set of circles on the image plane I corresponding to the distance Vp. That is, each defocused point of the scene looks like a circle on the image plane I. This circle is called a scattering circle, and the size C of the scattering circle represents the degree of defocus of an image at a position where the scattering circle is present. This scattering circle is determined by the distance from the lens 1 to the image plane H and the optical characteristics of the lens. In FIG. 4, the size (diameter) C of the scattering circle is

[0018]

[Equation 3]

It can be obtained by Next, the basic principle of rapidly generating an image in consideration of the depth of field in this embodiment will be described. When the image expressing the depth of field is observed when the predetermined lens characteristic is set, the object 5 in the defocus area near the focus position is detected according to the position (depth position) of the object as shown in FIG. The object 6 having a sharp contour and located in the front defocus region from the focal length, or the object 7 in the rear defocus region from the focal length, respectively, has a contour that becomes ambiguous as the distance from the focal length increases. It is considered that the brightness calculation processing in the defocus area (out-of-focus area) does not need to calculate the brightness particularly accurately due to the characteristics of the image in that portion.

Therefore, the focus area where the brightness needs to be calculated accurately and the defocus area where the brightness does not need to be calculated accurately are discriminated based on a predetermined method, for example, the formula 1 and the formula 2 or the formula 3. At the same time, accurate brightness calculation is performed based on the ray tracing method corresponding to the pinhole camera model that draws all pixels one by one in the focus area, and brightness calculation is performed in the defocus area according to the degree of defocus. In addition to increasing or decreasing the number of sampling points to perform, the brightness of the sampling pixels is calculated by distributed ray tracing using the predetermined filtering method for the pixels in the scattering circle. The pixels between the sampling pixels are linearly interpolated to calculate the luminance value, thereby reducing the calculation load of the defocus area and performing high-speed drawing.

That is, the luminance is calculated by densely sampling the number near the focal length, and the luminance is calculated by making the sampling number sparser as the distance from the focal length increases and the degree of out-of-focus increases. By linearly interpolating the luminance of the pixel of 1 with the luminance value of the sampling pixel, the number of time-consuming distributed tracing processes is reduced, and the drawing time is shortened.

In this case, the characteristics of the image (for example, very fine image, rough image, etc.), depth information of graphic data,
If the appropriate sampling rate (interpolation interval) is determined in consideration of the lens characteristics and the lens characteristics, the drawing processing speed and the image quality can be controlled. For example, if the sampling rate is set low, the quality of the drawn image is high, but the drawing speed is low. Conversely, if the sampling rate is increased, the drawing time is shortened according to the sampling rate, but the image quality is also lowered to some extent. By thus selecting an appropriate sampling rate according to the purpose of use, the image drawing speed and the image quality can be controlled.

FIG. 6 shows a pixel area 10 in which the degree of defocus is small based on the F number and the depth value of the pixel in the image in which the object 5, the object 6, and the object 7 are displayed.
FIG. 7 is a diagram showing a pixel region 11 having a medium degree of defocus and a pixel region 12 having a large degree of defocus.
Is a state where the sampling rate is reduced in the pixel area 10 to sample pixels, and the image area 11
6A and 6B are diagrams showing a state in which the sampling rate is set to a medium level and pixel sampling is performed, and a state in which the sampling rate is set to a high value in the image region 12 and pixel sampling is performed. In this way, the sampling rate is set according to the degree of defocus, only the brightness of the sampled pixels is calculated by distributed ray tracing, and the brightness values of the pixels between the sampling pixels are obtained by linear interpolation, It is possible to significantly reduce the brightness calculation time of the focus area.

[0024]

Second Embodiment FIGS. 8 and 9 are flowcharts showing another embodiment of the image drawing method of the present invention. This embodiment is a flow chart showing an example in which the image drawing method of the present invention is adopted in a raster scan system. In FIG.
First, graphic data including a depth value (z value) is obtained in step SP1, and coordinate conversion is performed in step SP2.
Predetermined graphic processing such as light source position setting is performed, lens characteristics used in step SP3 are set, pixels in the image are selected in step SP4, and step SP5
It is determined whether or not the selected pixel is defocused. If it is determined that the pixel is not defocused, that is, the pixel is defocused, the pixel immediately before the pixel selected in the scan line direction is defocused in step SP6. If it is determined that the focus is not defocused, the brightness of the pixel selected in step SP7 is calculated. On the other hand, if it is determined in step SP6 that the previous pixel is defocused, step S
In P8, the state of the previous pixel is set as the focus, and in step SP9, n processing target pixels are returned in the x direction (raster scan direction) according to the radius of the scattering circle.

When it is determined that the pixel is defocused in step SP5, it is determined whether the pixel immediately before the pixel selected in step SP10 is defocused, and when it is determined that the pixel is not defocused. Calculates the brightness of the selected pixel in step SP11, and x is calculated according to the radius of the scattering circle in step SP12.
N pixels to be processed are advanced in the direction. On the other hand, step S
If it is determined that the focus is defocused in P10, the brightness of each pixel is calculated by performing linear interpolation in the pixels up to the nth pixel in accordance with the selected pixel and the radius of the scattering circle in step SP13, and in step SP14. N pixels to be processed in the X direction according to the radius of the scattering circle,
Proceed.

Then, step SP7 and step SP
When the processing of step 9, step SP12, or step SP14 is completed, it is determined whether or not the pixel selected in step SP15 is the last pixel. If it is determined that the pixel is not the last pixel, in step SP16. The target pixel is advanced by one in the x direction, and the pixel selection process of step SP4 is performed again. On the other hand, if it is determined in step SP15 that the pixel is the last pixel, the series of processes ends.

The image drawing method of this embodiment is shown in FIG.
Will be described in more detail with reference to. In FIG. 10, ◯ indicates a defocused pixel and x indicates a focused pixel, and it is assumed that the scan line direction is the x direction (pixel arrangement direction in FIG. 10). First, Fig. 1
As shown in 0 (a), when the next pixel moved from the focus pixel is the focus, the brightness is calculated and determined for each pixel in the x direction. The part of the flowchart corresponding to this process corresponds to the process of step SP5 → step SP6 → step SP7.

Next, as shown in FIG. 10B, when the next pixel moved from the focused pixel is defocused, the brightness value of the defocused pixel is calculated (see FIG. 10B. ), The next sampling pixel is jumped according to the degree of defocus (specifically, the sampling rate determined by the radius of the scattering circle). The part of the flowchart corresponding to this process is step SP5 → step SP10 → step SP11 →
That is step SP12.

Next, as shown in FIG. 10C, when the next pixel moved from the defocused pixel is defocused, an interval is calculated based on the brightness of the previous pixel and the brightness value of the jumped pixel. After calculating the luminance value of the pixel by linear interpolation, the pixel jumps to the sampling pixel advanced by n. The part of the flowchart corresponding to this process is step SP5 → step SP10 → step SP13 → step SP14.

When the next pixel moved from the defocused pixel is the focus as shown in FIG. 10D, the previous pixel is made the focus and the pixel next to the previous pixel (that is, , Nth previous pixel). The part of the flowchart corresponding to this process is step SP5 → step SP6 → step SP8 → step SP9. Note that in FIG. 10D, when the returned pixel is in focus, the pixel is advanced by one as in FIG. 10A (see FIG. 10D1), and the returned pixel is defocused. In some cases, the brightness of the pixel of the defocus is calculated in the same manner as in FIG. 10B, and then the pixel is jumped to n pixels ahead (FIG. 10D2).
reference).

As described above, according to the image drawing method of this embodiment, even if focus and defocus pixels are mixed in the scan line direction in raster scanning,
Since the luminance of pixels can be sequentially determined based on the ray tracing method, the distributed tracing method, or the linear interpolation method, the image drawing method of the present invention is applied even to the most widely used raster scan display device. be able to.

[0032]

Third Embodiment FIGS. 11 and 12 are block diagrams showing an embodiment of the image drawing apparatus of the present invention. As shown in FIG. 11, this image drawing apparatus has a lens characteristic setting unit 31 that sets a predetermined lens characteristic that determines the depth of field, a graphic data processing unit 32 that performs coordinate conversion of graphic data, and a graphic processing. A data holding unit 33 that holds data, a scattering circle radius calculation unit 34 that calculates the scattering circle radius of a pixel based on the data of the data holding unit 33 and the data of the lens characteristic setting unit 31, and whether the pixel is in focus or not. Focus / defocus determination unit 35 that determines whether the focus is set
And a sampling rate determination unit 36 that determines the sampling rate based on the discrimination signal of the focus / defocus discrimination unit 35 and the scattering circle radius value from the scattering circle radius calculation unit 34.
A sampling section 37 for sampling, and a brightness calculation / drawing section 38 for calculating and drawing the brightness of pixels.
And an image memory 39. A CRT 40 as a display device is connected to the image memory 39.

As shown in FIG. 12, the brightness calculation / drawing unit 38 performs a convolution integration of a ray tracing unit 41 for determining the brightness of each pixel by the ray tracing method, and a brightness of each sampled pixel by a predetermined filter. Thus, the filtering brightness calculation unit 42 that calculates the brightness value of the sampling pixel and the sampling pixel drawing unit 43 that draws based on the brightness value of the sampling pixel
And an interpolated luminance calculation unit 44 that calculates the luminance value of the pixel between the sampling pixels by linear interpolation, and an interpolated pixel drawing unit 45 that draws based on the luminance value of the interpolated pixel. Note that the sampling pixel drawing unit 43 and the interpolation pixel drawing unit 45 form a defocus pixel drawing unit 46 that is integrated so that the drawing order of the sampling pixels and the interpolation pixels can be appropriately changed according to various drawing methods. Has become.

The operation of the image drawing apparatus having the above configuration will be briefly described. First, the lens characteristic setting unit 31 sets a lens characteristic that expresses a degree of subject depth, for example, a desired depth of field such as a wide-angle lens and a telephoto lens.
In addition, a plurality of sampling rates corresponding to the scattering circle radius range are set in advance in the sampling rate determining unit 36. Then, the graphic data including the depth information is changed by the graphic data processing unit 32 into data in which the viewpoint position and the arrangement of the light source are taken into consideration and held in the data holding unit 33, and the scattering circle radius calculation unit 34 sets the lens characteristic setting. The radius of the scattering circle on the image plane is calculated based on the lens characteristic of the unit 31 and the depth value of the pixel. Then, the focus / defocus determination unit 35
Then, a radius value serving as a reference for discriminating between focus and defocus is set in advance, and the focus / defocus discrimination unit 35 compares the calculated scattering circle radius with the reference radius value to determine which pixel is the focus. A pixel that is defocused is determined.

When it is determined that the pixel is in focus, the sampling rate determining unit 36 determines the sampling rate for sampling all pixels in response to the determination signal that the pixel is in focus, and the sampling unit 37 performs sampling. Then, the ray tracing section 41 is 1
The brightness value is determined for each pixel and drawn in the image memory 41.
On the other hand, when it is determined that the focus is defocused, the determination signal that the focus is defocused indicates that the scattering circle radius calculation unit 34
The sampling rate determining unit 36 determines the sampling rate corresponding to the radius of the scattering circle. And
The sampling unit 37 samples the pixels, and the filtering brightness calculation unit 42 calculates the brightness. Further, the luminance of the pixels between the sampling pixels is calculated by the interpolation luminance calculation unit 44 by linear interpolation. Then, the sampling pixel drawing unit 43 and the interpolation pixel drawing unit 45 draw the sampling pixel and the interpolated pixel in the image memory 39. It should be noted that the focus / defocus determination unit 35 can also determine focus and defocus based on not only the size of the scattering circle but also the above equations 1 and 2.

According to this image drawing apparatus, since the pixels in the defocus area are sampled based on the sampling rate corresponding to the degree of defocus, even if the number of pixels to be subjected to distributed ray tracing is reduced and the calculation time is shortened. In addition, it is possible to suppress substantial deterioration of the image quality and to enjoy only the effect of improving the drawing speed. The present invention is not limited to the above embodiments, and various design changes can be made without departing from the scope of the present invention. For example, although the luminance value of the pixel between the sampled pixels is obtained by linear interpolation in the above-mentioned embodiment, other various interpolation methods can be adopted.

[0037]

As described above, the invention of claim 1 corresponds to the degree of defocus of a pixel in the defocus state,
Since the sampling rate is set and the luminance values of pixels between sampling pixels are interpolated and drawn, the number of convolution integrations of defocused pixels can be reduced without causing a substantial deterioration in image quality. It has a unique effect that an image expressing the depth of field can be drawn at high speed.

According to the second aspect of the invention, the sampling rate is set in accordance with the degree of defocus of the pixel in the defocused state, and the luminance value of the pixel between the sampling pixels is interpolated and drawn. It is possible to reduce the number of times of defocus pixel convolution integration without causing a general decrease in image quality, and it is possible to draw an image expressing the depth of field at high speed.

[Brief description of drawings]

FIG. 1 is a flowchart showing an embodiment of an image drawing method of the present invention.

FIG. 2 is a flow chart showing an embodiment of the image drawing method of the present invention.

FIG. 3 is a diagram for explaining a depth of field.

FIG. 4 is a diagram for explaining a method of calculating the size of a scattering circle.

FIG. 5 is a diagram for explaining a basic principle of generating an image at high speed in consideration of a depth of field.

FIG. 6 is a diagram showing regions having different degrees of defocus.

FIG. 7 is a diagram schematically showing sampled pixels when a sampling rate is changed according to the degree of defocus.

FIG. 8 is a flowchart showing another embodiment of the image drawing method of the present invention.

FIG. 9 is a flowchart showing another embodiment of the image drawing method of the present invention.

10 is a diagram for explaining the image drawing method shown in FIGS. 8 and 9. FIG.

FIG. 11 is a block diagram showing an embodiment of an image drawing apparatus of the present invention.

FIG. 12 is a block diagram showing a detailed configuration of a luminance calculation drawing unit.

[Explanation of symbols]

34 Scattering circle radius calculation unit 35 Focus / defocus determination unit 36 Sampling rate determination unit 37 Sampling unit 41 Ray tracing unit 42 Filtering brightness calculation unit 43 Sampling pixel drawing unit 44 Interpolation brightness calculation unit 45 Interpolation pixel drawing unit 46 Defocus pixel drawing Department

Claims (2)

[Claims] 1. An image drawing method for drawing an image expressing a depth of field assuming a predetermined lens characteristic, wherein whether the pixel is in a focus state based on the predetermined lens characteristic and the depth value of the pixel. It is determined whether or not it is in the defocus state, and in response to the determination that it is in the focus state, the sampling rate is determined so that sampling is performed for all the pixels, and the pixels are sampled.
The brightness value of the sampling pixel is calculated by the pinhole camera model and drawn, and the degree of defocus is calculated in response to the determination that the state is defocused, and based on the calculated degree of defocus. The pixel sampling rate is determined, the pixel is sampled based on the determined sampling rate, the pixels in the scattering circle corresponding to the sampling pixel are filtered to calculate the luminance value of the sampling pixel, and the pixel between the sampling pixels is calculated. Calculate the luminance value of by a predetermined interpolation method,
An image drawing method, which draws a sampling pixel and an interpolated pixel based on respective luminance values. 2. A focus / defocus determination means (35) for determining whether a pixel is in a focus state or a defocus state based on a predetermined lens characteristic and a depth value of the pixel, and a focus / defocus determination. In response to the means (35) determining that the pixel is in the focus state, the sampling rate is determined so that all pixels are sampled, and the pixels are sampled based on the sampling rate (36) (37). ), The focus pixel drawing means (41) for calculating and drawing the luminance value of the sampled pixel by the pinhole camera model, and the focus / defocus judging means (35) are judged to be in the defocused state. Defocus degree calculation that calculates the degree of defocus in response Means (34), sampling means (36) (37) for determining the sampling rate of the pixel based on the calculated degree of defocus, and sampling the pixel based on the sampling rate, and corresponding to the sampled pixel Sampling pixel brightness calculating means (42) for calculating the brightness value of the sampling pixel by filtering the pixels in the scattering circle, and interpolation pixel brightness calculating means (42) for calculating the brightness value of the pixel between the sampling pixels by a predetermined interpolation method. 44), and defocus pixel drawing means (43) (45) (4) for drawing the sampling pixel and the interpolated pixel based on the respective brightness values.
6) An image drawing device comprising: