Depth dependent filtering of image signal
View Patent ↗A method and apparatus for rendering of image data for a multi-view display, such as image data for a lenticular auto-stereoscopic display, is disclosed. The method comprises the steps of receiving an image signal representing a first image, the first image comprising 3D image data, and spatially filtering the first image signal to provide a second image signal. The second image signal represents a second image, the spatial filtering being, e.g., a low-pass filter, a high-pass filter or a combination of a low-pass and a high-pass filter. A strength of the spatial filter is determined by a reference depth of the first image and a depth of an image element of the first image. The second image is sampled to a plurality of sub-images, each sub-image being associated with a view direction of the image.
1. A method of rendering image data for a multi-view display ( 1 ), the method comprising the steps of:
receiving a first image signal representing a first image ( 50 ) comprising 3D image data not 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 ( 53 ), the spatial filtering comprising mapping an image element ( 52 ) of the first image to a set of one or more image elements ( 52 , 55 ) of the second image, where a strength of the spatial filter is determined by a reference depth of the first image and a depth of the image element of the first image, said strength determining a size of the set of image elements, and
sampling the second image to a plurality of sub-images, each sub-image being associated with a respective view direction of the image.
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 titter and a low-pass filter.
4. 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.
5. The method according to claim 1 where a visibility factor is applied to at least one of the set of image elements 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.
6. The method according to claim 5 where 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 a first minimum distance to the viewpoint, and where the visibility factor is equal to 1 when the image element of the first image is closer than the at least one image element of the second image to a second minimum distance to the viewpoint, and where the factor follows a gradually transition between the values of zero and one.
7. The method according to claim 1 where the depth of at least one of the set of image elements 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 image element of the first image and the set of the one or more image elements of the second image are aligned along a horizontal line of the first image.
9. The method according to claim 1 where the first image signal has a 2.5D video image format.
10. The method of claim 1 where the reference depth represents a depth at which the first image is in focus.
11. A multi-view display device comprising:
a display panel ( 1 ) comprising an array of display elements ( 20 , 51 ), the display elements being arranged in groups, each group being associated with a view direction (φ) of an image,
an optical element ( 2 ) for directing light emitted from the display panel so that light emitted from a group of display elements is directed into an angular distribution ( 30 - 34 ) associated with the view direction of the group,
said display device rendering image data for display by:
receiving a first image signal representing a first image ( 50 ) 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 ( 53 ), the spatial filtering comprising mapping an image element ( 52 ) of the first image to a set of one or more image elements ( 52 , 55 ) of the second image, where a strength of the spatial filter is determined by a reference depth of the first image and a depth of the image element of the first image, said strength determining a size of the set of image elements, and
sampling the second image to a plurality of sub-images, each sub-image being associated with a respective view direction of the image.
12. A signal rendering system comprising at least one processor including:
an input module for receiving a first image signal representing a first image ( 50 ) comprising 3D image data not yet rendered for multi-view display,
a rendering module for spatially filtering the first mage signal to provide a second image signal, the second image signal representing a second image ( 53 ), the spatial filtering comprising mapping an image element ( 52 ) of the first image to a set of one or more image elements ( 52 , 55 ) of the second image, where a strength of the spatial filter is determined by a reference depth of the first image and a depth of the image element of the first image, said strength determining a size of the set of image elements, and
an output module for sampling the second image to a plurality of sub-images, each sub-image being associated with a respective view direction of the image.
13. A computer program embodied in a non-transitory computer-readable medium for effecting the performance of a method of rendering image data for 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 a set of one or more image elements of the second image, where a strength of the spatial filter is determined by a reference depth of the first image and a depth of the image element of the first image, said strength determining a size of the set of image elements, and
sampling the second image to a plurality of sub-images, each sub-image being associated with a respective view direction of the image.