Depth dependent filtering of image signal

1. A method of rendering image data for effecting the production of sub-images by a multi-view display, the method comprising the steps of:

receiving a first image signal representing a first image comprising 3D image data not yet rendered for multi-view display;

spatially filtering the first image signal to provide a second image signal, the second image signal representing a second image, the spatial filtering comprising mapping an image element of the first image to at least one image element of the second image, where a strength of the spatial filter is dependent on a depth of the image element of the first image relative to a reference depth of the first image;

sampling the second image signal to define a plurality of said sub-images, each sub-image being associated with a different respective view direction of the image; and

displaying said plurality of said sub-images on the multi-view display,

wherein a visibility factor is applied to the at least one image element of the second image, the visibility factor being determined from a distance between a viewpoint and a spatial coordinate of the image element of the first image and a distance between the viewpoint and a spatial coordinate of the at least one image element of the second image,

and wherein the visibility factor is equal to zero when the at least one image element of the second image is closer than the image element of the first image to the viewpoint, and where the visibility factor is equal to one when the image element of the first image is closer than the at least one image element of the second image to the viewpoint, and where the visibility factor follows a gradual transition between the values of zero and one.

2. The method according to claim 1 where the spatial filter comprises a band-pass filter.

3. The method according to claim 2 where the band-pass filter is selected from a group consisting of a high-pass filter, a low-pass filter and a combination of a high-pass filter and a low-pass filter.

4. The method according to claim 1 where the image element of the first image is mapped to a number of the image elements of the second image and where the strength of the spatial filter determines the value of said number.

5. The method according to claim 4 where the image element of the first image and the number of image elements of the second image are aligned along a horizontal line of the first image.

6. The method according to claim 1 where the strength of the spatial filter is a function of a difference between the depth of the image element of the first image and the reference depth of the first image.

7. The method according to claim 1 where the depth of the at least one image element of the second image is updated from an initial depth to a value between the initial depth and the depth of the image element of the first image, so that the sampling of the second image is done using the updated depth of the at least one image element of the second image.

8. The method according to claim 1 where the first image signal has a 2.5D video image format.

9. The method of claim 1 where the reference depth represents a depth at which the first image is in focus.

10. A multi-view display device comprising:

a display panel comprising an array of display elements, the display elements being arranged in groups, each group being associated with a different respective view direction (φ) of an image; and

an optical element for directing light emitted from the display panel so that light emitted from each group of display elements is directed into an angular distribution associated with the view direction of the group;

said multi-view display device rendering image data for effecting the production of subimages by:

receiving a first image signal representing a first image comprising 3D image data not yet rendered for multi-view display;

spatially filtering the first image signal to provide a second image signal, the second image signal representing a second image, the spatial filtering comprising mapping an image element of the first image to at least one image element of the second image, where a strength of the spatial filter is dependent on a depth of the image element of the first image relative to a reference depth of the first image;

sampling the second image signal to define a plurality of said sub-images, each sub-image being associated with one of said a different respective view directions of the image; and

displaying said plurality of said sub-images on the display panel,

wherein a visibility factor is applied to the at least one image element of the second image, the visibility factor being determined from a distance between a viewpoint and a spatial coordinate of the image element of the first image and a distance between the viewpoint and a spatial coordinate of the at least one image element of the second image,

and wherein the visibility factor is equal to zero when the at least one image element of the second image is closer than the image element of the first image to the viewpoint, and where the visibility factor is equal to one when the image element of the first image is closer than the at least one image element of the second image to the viewpoint, and where the visibility factor follows a gradual transition between the values of zero and one.

11. A signal rendering system for rendering image data for effecting the production of sub-images by a multi-view display, said system comprising at least one processor including:

an input module for receiving a first image signal representing a first image comprising 3D image data not yet rendered for multi-view display;

a rendering module for spatially filtering the first image signal to provide a second image signal, the second image signal representing a second image, the spatial filtering comprising mapping an image element of the first image to at least one image element of the second image, where a strength of the spatial filter is dependent on a depth of the image element of the first image relative to a reference depth of the first image;

an output module for sampling the second image signal to define a plurality of said sub-images, each sub-image being associated with a different respective view direction of the image; and

a display module for displaying said plurality of said sub-images on the multi-view display,

wherein a visibility factor is applied to the at least one image element of the second image, the visibility factor being determined from a distance between a viewpoint and a spatial coordinate of the image element of the first image and a distance between the viewpoint and a spatial coordinate of the at least one image element of the second image,

and wherein the visibility factor is equal to zero when the at least one image element of the second image is closer than the image element of the first image to the viewpoint, and where the visibility factor is equal to one when the image element of the first image is closer than the at least one image element of the second image to the viewpoint, and where the visibility factor follows a gradual transition between the values of zero and one.

12. A computer program embodied in a non-transitory computer readable medium for effecting the performance of a method of rendering image data for producing sub-images on a multi-view display, the method comprising the steps of:

receiving a first image signal representing a first image comprising 3D image data not yet rendered for multi-view display;

spatially filtering the first image signal to provide a second image signal, the second image signal representing a second image, the spatial filtering comprising mapping of an image element of the first image to at least one image element of the second image, where a strength of the spatial filter is dependent on a depth of the image element of the first image relative to a reference depth of the first image;

sampling the second image signal to define a plurality of said sub-images, each sub-image being associated with a different respective view direction of the image; and

displaying said plurality of said sub-images on the multi-view display,

wherein a visibility factor is applied to the at least one image element of the second image, the visibility factor being determined from a distance between a viewpoint and a spatial coordinate of the image element of the first image and a distance between the viewpoint and a spatial coordinate of the at least one image element of the second image,

and wherein the visibility factor is equal to zero when the at least one image element of the second image is closer than the image element of the first image to the viewpoint, and where the visibility factor is equal to one when the image element of the first image is closer than the at least one image element of the second image to the viewpoint, and where the visibility factor follows a gradual transition between the values of zero and one.