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US 10,963,999 B2Granted
Methods and apparatus for contrast sensitivity compensation
AssigneeIrisvision, Inc.
InventorsFrank Werblin, Robert Massof, Chris Bradley
Life of this patent
Estimating the term…
Abstract
A system and methods for contrast sensitivity compensation provides for correcting the vision of users whose vision is deficient for discerning high spatial frequencies. The system and methods use measurements of the user's contrast detection as a function of spatial frequency in the image to correct images in real time. The system includes a head-mountable device that includes a camera and a processor that can provide enhanced images at video framing rates.
Claims15
A method of providing enhanced video images to a user p, the method comprising:
- obtaining, via a programmable electronic device, video images comprising a plurality of input images A;
- computing, in the programmable electronic device, an application of a contrast enhancement function to the plurality of input images A to form a plurality of contrast enhanced images comprising contrast enhanced video images C where the contrast enhancement function is user-specific and where the contrast enhancement function is frequency-dependent, and
- presenting, on a display of the programmable electronic device and to the user, the contrast enhanced video images C,
- such that the contrast enhanced video images are preferentially enhanced at a spatial frequency cut-off Cp, where Cp is the maximum spatial frequency at which a user can discern contrast.
1 more element
A method of providing enhanced images to a user p using a programmable electronic device, the method comprising:
- obtaining input video images comprising a plurality of input images A, where each image of the plurality of input images includes a luminance image Y(x,y) and chrominance images CB (x,y), CR(x,y);
- forming a contrast enhancement function CEFp(u), as
- CEF
- p
-
- (
- u
- )
- =
- {
- CSF
- n
-
- (
- u
- ×
- c
- n
- c
- p
- )
- CSF
- p
-
- (
- u
- )
- for
-
-
- u
- ≤
- c
- p
- 1
- for
-
-
- u
- >
- c
- p
- ,
- where CSFp(u), is a contrast sensitivity function for the user p corresponding to minimum discernable contrasts to the user p as a function spatial frequency u,
- where cP is a spatial frequency cut-off for the user p, which is the maximum spatial frequency at which the user can discern contrast,
- where CSFn(u) is a contrast sensitivity function for persons n having normal contrast sensitivity, and
- where cn is a spatial cut-off frequency for persons n, which is the maximum spatial frequency at which said persons n can discern contrast;
- computing, in the programmable electronic device, an application of the contrast enhancement function to the plurality of input images A to form a plurality of contrast enhanced images comprising contrast enhanced video images C where the application includes
- performing a Fourier transform on the luminance image Y(x,y) to obtain a luminance amplitude My(u), and phase, Py(u),
- enhancing the luminance amplitude by M (u)=My(u)×CEFp(u),
- performing an inverse Fourier transform on M (u) and Py(u) to obtain an enhanced luminance image Y′(x,y), and
- combining the enhanced luminance image is combined with unaltered
- chrominance images form contrast enhanced video images:
- C(x,y)=[Y′(x,y),CB(x,y),CR(x,y)] presenting, on a display of the programmable electronic device and to the user, the contrast enhanced video images C=C (x,y),
- such that the contrast enhanced video images are preferentially enhanced at spatial frequencies discernable to the user.
52 more elements
A contrast sensitivity compensation system wearable by a user p, the system comprising:
- a memory including a stored program;
- a camera mounted on the user p aimed to view a scene in front of the user p and operable to obtain input video images of the scene comprising a plurality of input images A;
- a processor programmed to execute the stored program to
- compute the application of a contrast enhancement function to the plurality of input images A to form a plurality of contrast enhanced images comprising contrast enhanced video images C, where the contrast enhancement function is user-specific, and where the contrast enhancement function is frequency-dependent;
- and
- present, to the user on a display of a programmable electronic device, the contrast enhanced video images C=C (x,y), such that the contrast enhanced video images are preferentially enhanced at a spatial frequency cut-off Cp, where Cp is the maximum spatial frequency at which the user can discern contrast.
3 more elements
A contrast sensitivity compensation system wearable by a user, the system comprising:
- a memory including a stored program;
- a camera mounted on the user aimed to view a scene in front of the user and operable to obtain input video images of the scene comprising a plurality of input images A, where each image of the plurality of input images includes a luminance image Y(x,y) and chrominance images C8(x,y), CR(x,y);
- a processor programmed to execute the stored program to
- compute an the application of a contrast enhancement function to the plurality of input images A to form a plurality of contrast enhanced images comprising contrast enhanced video images C,
- where the contrast enhancement function is user-specific and is
- CEF
- p
-
- (
- u
- )
- =
- {
- CSF
- n
-
- (
- u
- ×
- c
- n
- c
- p
- )
- CSF
- p
-
- (
- u
- )
- for
-
-
- u
- ≤
- c
- p
- 1
- for
-
-
- u
- >
- c
- p
- ,
- where CSFμ(u) is a contrast sensitivity function for the user p corresponding to a minimum discernable contrasts to the user as a function spatial frequency u,
- where cP is a spatial frequency cut-off for the user, which is the maximum spatial frequency at which the user can discern contrast,
- where CSFn(u) is a contrast sensitivity function for persons n having normal contrast sensitivity,
- where cn is a spatial cut-off frequency for persons n, which is the maximum spatial frequency at which said persons n can discern contrast,
- and where the processor is further programmed to execute the stored program to
- perform a Fourier transform on the luminance image Y (x,y) to obtain a luminance amplitude My(u) and phase Py(u),
- enhance the luminance amplitude by M (u)=My(u)×CEFp(u),
- perform an inverse Fourier transform on M (u) and Py(u) to obtain an enhanced luminance image Y′ (x,y) and
- the enhanced luminance image is combined with unaltered chrominance images to form contrast enhanced video images:
- C(x,y)=[Y′(x,y), C8 (x,y), CR(x,y)];
- and
- present to the user, on a display, of the, the contrast enhanced video images C=C(x,y).
55 more elements
Dependencies are inferred from the claim text.