PROJECTOR AND PROJECTION METHOD

• US 20090115916A1
• Filed: 11/06/2008
• Published: 05/07/2009
• Est. Priority Date: 11/06/2007
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Takahashi, Toru, Kondo, Satoshi, Aoki, Takafumi
• Granted Patent: US 7,857,461 B2
• Time in Patent Office: Days
• US Class Current: 348/745
• CPC Class Codes: H04N 5/74 Projection arrangements for image reproduction, e.g. using eidophor
• CPC Class Codes: H04N 9/3185 Geometric adjustment, e.g. keystone or convergence optical or mechanical adjustment of convergence H04N9/317; using scanning means H04N3/22; optical or mechanical adjustments of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/14
• CPC Class Codes: H04N 9/3194 including sensor feedback

Abstract

A projector includes: an image capturing unit that captures an image of a projection target image (an original image or a corrected image) projected by the projector on a projection surface; a shape model hold unit that holds shape models; a model selection unit that selects a projection surface shape model based on correspondence relationships between first feature points on the projection target image and second feature points on the captured image; a parameter calculation unit that calculates a model parameter which is to be used to approximate a shape of the projection surface shape model to the shape of the projection surface and indicates a positional relationship between the projection surface and the projector, for each projection target image based on the correspondence relationships; a correction unit that corrects another original image; and a projection unit that projects the corrected image as another projection target image.

Claims

1. A projector that projects inputted original images on a projection surface, said projector comprising;

an image capturing unit configured to capture an image of a projection target image projected by said projector on the projection surface, the projection target image being an original image to be projected or a corrected image generated by correcting an original image;

a shape model hold unit configured to hold shape models each expressing a corresponding predetermined type of a shape;

a model selection unit configured to select, as a projection surface shape model, a shape model expressing a type of a shape of the projection surface from among the shape models held in said is shape model hold unit based on correspondence relationships between first feature points on the projection target image and second feature points on the image captured by said image capturing unit;

a parameter calculation unit configured to calculate a model parameter using the projection surface shape model based on correspondence relationships between the first feature points on the projection target image and the second feature points on the image captured by said image capturing unit in order to approximate the image captured by said image capturing unit to the original image, the model parameter being used to approximate a shape of the projection surface shape model to the shape of the projection surface and indicating a positional relationship between the projection surface and said projector, and the calculation being performed for each of projection target images including the projection target image;

a correction unit configured to, when the model parameter is calculated, correct another original image to be projected using the projection surface shape model and the model parameter; and

a projection unit configured to project, as another projection target image, the corrected image corrected by said correction unit on the projection surface.

2. The projector according to claim 1,

wherein said parameter calculation unit is configured to repeatedly calculate the model parameter until coordinates of the second feature points are modified using the projection surface shape model and the model parameter to be approximated to coordinates of points which are on the original image and correspond to the second feature points.

3. The projector according to claim 1,

wherein said parameter calculation unit is configured to repeatedly calculate the model parameter until the image captured by said image capturing unit is approximated to an image enlarged or reduced from the original image.

4. The projector according to claim 1,

wherein said model selection unit configured to select a single projection surface shape model from among the shape models held in said shape model hold unit for the projection target images, and

said parameter calculation unit is configured to calculate the model parameter using the single projection surface shape model for each of the projection target images, so that the calculation for the projection target images being performed depending on (i) the shape of the projection surface and (ii) a change in the positional relationship between the projection surface and said projector.

5. The projector according to claim 1,

wherein said parameter calculation unit is configured to calculate the model parameter using a shape model assuming that the shape model is the projection surface shape model to be selected from among the shape models held in said shape model hold unit, and

said model selection unit is configured to select the shape model as the projection surface shape model, so that (i) the number of certain points among the second feature points which are modified using the model parameter corresponding to the selected shape model exceeds a second threshold value and that (ii) a difference between (ii-1) coordinates of each of the certain points and (ii-2) coordinates of a point which is on the original image and corresponds to the each of the certain points is equal to or less than a first threshold value.

6. The projector according to claim 1,

wherein said parameter calculation unit is configured to calculate a plurality of the model parameters using a plurality of shape models assuming that one shape model of the plurality of shape models is the projection surface shape model to be selected from among the shape models held in said shape model hold unit, and

said model selection unit is configured to select the one shape model from among the plurality of shape models as the projection surface shape model, so that coordinates of the second feature points modified using the model parameter corresponding to the one shape model are most approximated to coordinates of points which are on the original image and correspond to the second feature points.

7. The projector according to claim 1,

wherein said model selection unit is configured to select the projection surface shape model according to a signal provided from outside of said projector.

8. The projector according to claim 1,

wherein the shape model hold unit is configured to hold, as the shape models, at least one of a projection transformation model, a cylinder model, a sphere model, and a thin plate spline model.

9. A projection method of projecting inputted original images on a projection surface, said projection method comprising;

capturing an image of a projection target image projected by a projector on the projection surface, the projection target image being an original image to be projected or a corrected image generated by correcting an original image;

selecting, as a projection surface shape model, a shape model expressing a type of a shape of the projection surface from among the shape models each expressing a corresponding predetermined type of a shape based on correspondence relationships between first feature points on the projection target image and second feature points on the image captured in said capturing;

calculating a model parameter using the projection surface shape model based on correspondence relationships between the first feature points on the projection target image and the second feature points on the image captured in said capturing in order to approximate the image captured in said capturing to the original image, the model parameter being used to approximate a shape of the projection surface shape model to the shape of the projection surface and indicating a positional relationship between the projection surface and the projector, and the calculation being performed for each of projection target images including the projection target image;

correcting another original image to be projected using the projection surface shape model and the model parameter, when the model parameter is calculated; and

projecting, as another projection target image, the corrected image corrected in said correcting on the projection surface.

10. An integrated circuit which controls a projector that projects inputted original images on a projection surface, said integrated circuit comprising;

an image capturing unit configured to capture an image of a projection target image projected by said projector on the projection surface, the projection target image being an original image to be projected or a corrected image generated by correcting an original image;

a shape model hold unit configured to hold shape models each expressing a corresponding predetermined type of a shape;

a model selection unit configured to select, as a projection surface shape model, a shape model expressing a type of a shape of the projection surface from among the shape models held in said shape model hold unit based on correspondence relationships between first feature points on the projection target image and second feature points on the image captured by said image capturing unit;

a parameter calculation unit configured to calculate a model parameter using the projection surface shape model based on correspondence relationships between the first feature points on the projection target image and the second feature points on the image captured by said image capturing unit in order to approximate the image captured by said image capturing unit to the original image, the model parameter being used to approximate a shape of the projection surface shape model to the shape of the projection surface and indicating a positional relationship between the projection surface and said projector, and the calculation being performed for each of projection target images including the projection target image;

a correction unit configured to, when the model parameter is calculated, correct another original image to be projected using the projection surface shape model and the model parameter; and

a projection unit configured to project, as another projection target image, the corrected image corrected by said correction unit on the projection surface.

11. A computer program recorded on a computer-readable recording medium to project images on a projection surface, said computer program causing a computer to execute;

capturing an image of a projection target image projected by a projector on the projection surface, the projection target image being an original image to be projected or a corrected image generated by correcting an original image;

selecting, as a projection surface shape model, a shape model expressing a type of a shape of the projection surface from among the shape models each expressing a corresponding predetermined type of a shape based on correspondence relationships between first feature points on the projection target image and second feature points on the image captured in said capturing;

calculating a model parameter using the projection surface shape model based on correspondence relationships between the first feature points on the projection target image and the second feature points on the image captured in said capturing in order to approximate the image captured in said capturing to the original image, the model parameter being used to approximate a shape of the projection surface shape model to the shape of the projection surface and indicating a positional relationship between the projection surface and the projector, and the calculation being performed for each of projection target images including the projection target image;

correcting another original image to be projected using the projection surface shape model and the model parameter, when the model parameter is calculated; and

projecting, as another projection target image, the corrected image corrected in said correcting on the projection surface.