Light field display metrology
View Patent ↗Examples of a light field metrology system for use with a display are disclosed. The light field metrology may capture images of a projected light field, and determine focus depths (or lateral focus positions) for various regions of the light field using the captured images. The determined focus depths (or lateral positions) may then be compared with intended focus depths (or lateral positions), to quantify the imperfections of the display. Based on the measured imperfections, an appropriate error correction may be performed on the light field to correct for the measured imperfections. The display can be an optical display element in a head mounted display, for example, an optical display element capable of generating multiple depth planes or a light field display.
1. An optical metrology system for performing image correction on a display, the system comprising:
a camera configured to capture an image of a light field projected by a display, the light field associated with a display layer of the display;
a hardware processor programmed with executable instructions to:
generate a vector field based at least partly on the image captured by the camera, the vector field comprising vectors corresponding to deviations between projected positions and expected positions of points of the display layer;
calculate, based at least partly on the vector field, at least one of: a centration correction, an aggregate rotation correction, an aggregate scaling correction, or a spatial mapping, for the display;
calculate, based at least partly upon the image captured by the camera, luminance values corresponding to a plurality of points on the display layer; and
calculate, based at least partly on the determined luminance values, a luminance flattening correction or a chromatic balancing correction, for the display.
2. The optical metrology system of claim 1 , wherein the display layer of the display comprises a color layer or a depth layer.
3. The optical metrology system of claim 1 , wherein the camera comprises a light field camera or a digital camera having a small depth of focus.
4. The optical metrology system of claim 1 , wherein to calculate the centration correction, the hardware processor is programmed to determine a translation vector corresponding to a translation error between an identified center point of the projected display layer and an expected center point position.
5. The optical metrology system of claim 1 , wherein to calculate the aggregate rotation correction, the hardware processor is programmed to determine a rotational amount corresponding to a rotation of the projected display layer about a center point, such that a pixel error amount between the projected positions and the expected positioned is reduced or minimized.
6. The optical metrology system of claim 1 , wherein to calculate the aggregate rotation correction, the hardware processor is programmed to calculate a curl of the vector field.
7. The optical metrology system of claim 1 , wherein to calculate the aggregate scaling correction, the hardware processor is programmed to determine a scaling amount corresponding to a scaling of the projected display layer about a center point, such that a pixel error amount between the projected positions and the expected positioned is reduced or minimized.
8. The optical metrology system of claim 1 , wherein to calculate the aggregate scaling correction, the hardware processor is programmed to calculate a divergence of the vector field.
9. The optical metrology system of claim 1 , wherein to calculate the spatial mapping, the hardware processor is programmed to determine a non-linear transformation to align the projected positions of the display layer with the expected positions.
10. The optical metrology system of claim 1 , wherein to calculate the luminance flattening correction, the hardware processor is programmed to:
determine a threshold luminance value; and
calculate an amount that lowers each luminance value greater than the threshold luminance value to the threshold luminance value.
11. The optical metrology system of claim 1 , wherein to calculate the chromatic balancing correction, the hardware processor is programmed to:
identify a color cluster associated with the display layer, the color cluster comprising at least one additional display layer;
for each point of the display layer, compare the luminance value corresponding to the point on the display layer with a luminance value corresponding to the point on the additional display layer; and
calculate an amount that lowers each luminance value to the lowest luminance value associated with its corresponding point.