Image shadow elimination method, image processing apparatus,...

Computer graphics processing and selective visual display system – Computer graphics processing – Three-dimension

Reexamination Certificate

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Details

C345S426000

Reexamination Certificate

active

06320578

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a method of eliminating shadows contained in an image when a photographic image taken with a video camera, a still camera, or the like is pasted on the surface of a 3-D model (texture mapping), for example, in authoring 3-D contents, and further relates to an image processing apparatus provided with a function of eliminating shadows contained in an image and a recording medium readable by the image processing apparatus.
In authoring 3-D contents, the texture mapping technique of pasting an image on the surface of a 3-D model is used so that texture will be well expressed and a realistic atmosphere can be created.
However, when a photographic image taken with a video camera, a still camera, or the like is pasted on the surface of a 3-D model, the photographic image is shaded by the rendering performed at the final stage of the 3-D graphics process, which requires an operation to eliminate the shadows.
Conventionally, the elimination of shadows from images is conducted by operators' manual work with photo-retouching software.
The procedure is as follows. At first, shadow areas are designated: the shadow areas are roughly designated by setting an approximate color range, and then minute portions are corrected by manual work.
Then, the contrast and the brightness of the designated areas are changed in order to make the areas have the same color as the portions with no shadows.
However, such an operation of changing the contrast and the brightness of the designated areas by using the photo-retouching software requires skill, so that even professional designers cannot produce satisfactory works without sufficient experience.
BRIEF SUMMARY OF THE INVENTION
The present invention has been devised to solve these problems and has an object of providing an image shadow elimination method which allows users with no photo-retouching knowledge to eliminate shadows by simple operations by estimating the position of a light source by superimposing a 3-D model on an image containing shadows and eliminating the shadows from the areas where the shadows will be created by the rendering for the 3-D model at the position of the light source, further providing an image processing apparatus provided with a function of eliminating shadows, and a recording medium readable by the image processing apparatus.
The present invention is characterized by superimposing a three-dimensional model on the picture of the three-dimensional object contained in the image so as to fit the three-dimensional model to the picture; designating a shadow plane of the picture of the three-dimensional object contained in the image; estimating the position of a light source, based on a plane of the three-dimensional model superimposed on the designated plane; searching an area on which a shadow is to be created by a rendering for the three-dimensional model based on the estimated position of the light source, and deciding that an area on which the searched out plane is superimposed is a shadow area of the image; and eliminating the shadow from the area which has been decided as the shadow area.
Consequently, users with no photo-retouching knowledge can eliminate the shadow contained in the image by simple operations of superimposing a 3-D model on the image so as to fit the shape to the picture and designating the plane of the shadow contained in the image.
The present invention is further characterized by superimposing a three-dimensional model on the picture of the three-dimensional object contained in the image so as to fit the three-dimensional model to the picture; designating a point on the picture of the three-dimensional object contained in the image and a position of the point on a shadow; estimating a position of a light source, based on a point and position of the three-dimensional model superimposed on the picture of the three-dimensional object corresponding to the designated point and position; deciding that an area on which a shadow is created by a rendering for the three-dimensional model based on the light source at the estimated position is the shadow area of the image; and eliminating the shadow from the area which has been decided as the shadow area.
Consequently, users with no photo-retouching knowledge can eliminate the shadow contained in the image by simple operations of superimposing a 3-D model on the image so as to fit the shape to the picture and designating a point on the photographic image of a three-dimensional object contained in the image and the position of the point in the shadow.
The present invention is further characterized by superimposing a three-dimensional model on the picture of the three-dimensional object contained in the image so as to fit the three-dimensional model to the picture; designating a position of a light source; searching an area on which a shadow is to be created by a rendering for the three-dimensional model based on the designated position of the light source; changing the position of the light source when the shadow created by the rendering does not agree with a shadow of the image; deciding that the area on which the shadow is created by the rendering is the shadow area of the image when the shadow created by the rendering agrees with the shadow of the image; and eliminating the shadow from the area which has been decided as the shadow area.
Consequently, users with no photo-retouching knowledge can eliminate the shadow contained in the image by simple operations of superimposing a 3-D model on the image so as to fit the shape to the picture, designating the position of the light source, and changing the position of the light source until the shadow created by the rendering for the 3-D model agrees with the shadow contained in the image.
The present invention is further characterized by, when a shadow is eliminated from the area which has been decided as a shadow area, calculating a pixel distribution of an area which has been decided as a shadow area and a pixel distribution of an area other than the shadow area in the image; calculating a conversion function, based on the pixel distributions, for converting the pixel distribution of the shadow area into a pixel distribution in accordance with the pixel distribution of the area other than the shadow area; and converting the pixel distribution of the shadow area by the conversion function.
Consequently, the shadow contained in the image is eliminated without operating the contrast and the brightness of the shadow area.
The present invention is further characterized by, when a shadow is eliminated from the area which has been decided as a shadow area, calculating a pixel distribution of a portion of an area which has been decided as a shadow area and a pixel distribution of a portion of the area other than the shadow area in the image, the portions being same in color; calculating a conversion function for converting the pixel distribution of the shadow area into a pixel distribution in accordance with the calculated pixel distribution; and converting the pixel distribution of the shadow area by the conversion function.
Consequently, the shadow contained in the image is eliminated by simple operations of designating a portion in a shadow area and a portion in the other area which are same in color, without changing the contrast and the brightness of the shadow area. The shadow is eliminated without this designation when the image processing apparatus is provided with a function of distinguishing a portion in the shadow area and a portion in the other area which are same in color.
The present invention is further characterized by, when a shadow is eliminated from the area which has been decided as a shadow area, calculating pixel distributions of respective portions in an area which has been decided as a shadow area and pixel distributions of respective portions which have same colors as the respective portions of the shadow area, respectively in an area other than the shadow area in the image; calculating conversion functions for converting the pixel d

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