Calibrating pixel elements
A composite display is disclosed. In some embodiments, a composite display includes a paddle configured to sweep out an area, a plurality of pixel elements mounted on the paddle, and one or more optical sensors mounted on the paddle and configured to measure luminance values of the plurality of pixel elements. Selectively activating one or more of the plurality of pixel elements while the paddle sweeps the area causes at least a portion of an image to be rendered.
1 . A method for calibrating pixel elements of a composite display, comprising:
comparing a current luminance value of white light of a temporal pixel to a baseline luminance value of white light of the temporal pixel, wherein the temporal pixel corresponds to a set of one or more pixel elements at a given sweep location; and
if the current luminance value of white light of the temporal pixel is greater than the baseline luminance value of white light of the temporal pixel by at least a prescribed amount:
concluding that at least one pixel element in the set of pixel elements has a shift in its spectrum; and
at least in part compensating for the shift in the spectrum of the at least one pixel element;
wherein each of the current luminance value of white light of the temporal pixel and the baseline luminance value of white light of the temporal pixel is determined by simultaneously activating the set of pixel elements and using one or more optical sensors associated with the set of pixel elements.
2 . A method as recited in claim 1 , wherein concluding that at least one pixel element in the set of pixel elements has a shift in its spectrum comprises concluding that the at least one pixel element is being overdriven.
3 . A method as recited in claim 1 , further comprising, for each of at least a subset of. pixel elements included in the set, restoring a current luminance value of a pixel element to a baseline luminance value associated with the pixel element if the current luminance value of the pixel element is different than the baseline luminance value of the pixel element.
4 . A method as recited in claim 1 , further comprising determining the current luminance value of white light of the temporal pixel.
5 . A method as recited in claim 1 , wherein the baseline luminance value of white light of the temporal pixel is determined during manufacturing or set-up of the composite display.
6 . A method as recited in claim 1 , wherein the set of pixel elements comprises one or more red, green, and blue light emitting diodes (LEDs).
7 . A method as recited in claim 1 , wherein the one or more optical sensors comprise one or more broadband photodetectors.
8 . A method as recited in claim 1 , wherein each of the current luminance value of white light of the temporal pixel and the baseline luminance value of white light of the temporal pixel is determined by averaging readings of two or more of the optical sensors.
9 . A method as recited in claim 1 , wherein at least in part compensating for the shift in the spectrum of the at least one pixel element comprises restoring the current luminance value of white light of the temporal pixel to the baseline luminance value of white light of the temporal pixel.
10 . A method as recited in claim 1 , wherein at least in part compensating for the shift in the spectrum of the at least one pixel element comprises restoring a current chromaticity of white light of the temporal pixel so that it does not include a bias towards a particular color towards which the spectrum of the at least one pixel element has shifted.
11 . A method as recited in claim 1 , wherein at least in part compensating for the shift in the spectrum of the at least one pixel element comprises underdriving one or more pixel elements of the set that are of a color towards which the spectrum of the at least one pixel element has shifted.
12 . A method as recited in claim 1 , wherein at least in part compensating for the shift in the spectrum of the at least one pixel element comprises redefining a color map of the composite display, wherein the color map maps colors from a source image to a color space of the composite display.
13 . A method as recited in claim 12 , wherein redefining the color map comprises locally restricting an available color space of a set of temporal pixels, including the temporal pixel, rendered by the set of pixel elements to a smallest color gamut available to any temporal pixel in the set of temporal pixels.
14 . A method as recited in claim 12 , wherein redefining the color map comprises globally restricting an available color space of all temporal pixels in the composite display, including the temporal pixel, to a smallest color gamut available to any temporal pixel in the composite display.
15 . A method as recited in claim 1 , wherein each of the current luminance value of white light of the temporal pixel and the baseline luminance value of white light of the temporal pixel is associated with a set of temporal pixels, including the temporal pixel, that is rendered by the set of pixel elements.
16 . A system for calibrating pixel elements of a composite display, comprising:
a processor configured to:
compare a current luminance value of white light of a temporal pixel to a baseline luminance value of white light of the temporal pixel, wherein the temporal pixel corresponds to a set of one or more pixel elements at a given sweep location; and
if the current luminance value of white light of the temporal pixel is greater than the baseline luminance value of white light of the temporal pixel by at least a prescribed amount:
conclude that at least one pixel element in the set of pixel elements has a shift in its spectrum; and
at least in part compensate for the shift in the spectrum of the at least one pixel element; and
a memory coupled to the processor and configured to provide the processor with instructions;
wherein each of the current luminance value of white light of the temporal pixel and the baseline luminance value of white light of the temporal pixel is determined by simultaneously activating the set of pixel elements and using one or more optical sensors associated with the set of pixel elements
17 . A computer program product for calibrating pixel elements of a composite display, the computer program product being embodied in a computer readable storage medium and comprising computer instructions for:
comparing a current luminance value of white light of a temporal pixel to a baseline luminance value of white light of the temporal pixel, wherein the temporal pixel corresponds to a set of one or more pixel elements at a given sweep location; and
if the current luminance value of white light of the temporal pixel is greater than the baseline luminance value of white light of the temporal pixel by at least a prescribed amount:
concluding that at least one pixel element in the set of pixel elements has a shift in its spectrum; and
at least in part compensating for the shift in the spectrum of the at least one pixel element;
wherein each of the current luminance value of white light of the temporal pixel and the baseline luminance value of white light of the temporal pixel is determined by simultaneously activating the set of pixel elements and using one or more optical sensors associated with the set of pixel elements.
18 . A computer program product as recited in claim 17 , wherein at least in part compensating for the shift in the spectrum of the at least one pixel element comprises restoring the current luminance value of white light of the temporal pixel to the baseline luminance value of white light of the temporal pixel.
19 . A computer program product as recited in claim 17 , wherein at least in part compensating for the shift in the spectrum of the at least one pixel element comprises underdriving one or more pixel elements of the set that are of a color towards which the spectrum of the at least one pixel element has shifted.
20 . A computer program product as recited in claim 17 , wherein at least in part compensating for the shift in the spectrum of the at least one pixel element comprises redefining a color map of the composite display, wherein the color map maps colors from a source image to a color space of the composite display.