Patent Description:
This application relates generally to projection systems and methods of correcting uniformity errors in an image frame.

Digital projection systems typically utilize a light source and an optical system to project an image onto a surface or screen. The light source, acting as a color display, mixes primary colors to make other colors. To display or project a particular color, a precise mixture is required and must be repeated over the entire image frame. When displaying a pure white image, for example, the light source maximizes the red, green, and blue values at each point on the surface or screen. However, when the precise mixture is not the same over the entire image frame, the image has a uniformity error. Uniformity errors may be caused by physical characteristics of the digital projection system (e.g., manufacturing tolerances, wear and tear on projector components, thermal effects, bent cables, and the like). The image uniformity errors can be categorized into chromaticity uniformity errors and luminance uniformity errors. For example, chromaticity tinting may occur along the edges of the projected image (a chromaticity uniformity error), or some sections of the projected image may appear brighter than others (a luminance uniformity error). <CIT> discloses a control system for a projection display including means for compensating for spatial variations or artifacts in light scattered by a projection screen. A sensor produces a signal corresponding to the amount of light scattered to a viewer on a region-by-region or pixel-by-pixel basis. A screen map is created from the sensor signal. Input display data is convolved with the screen map to produce a compensated display signal. The compensated display signal drives a projection display engine. The projected light driven by the compensated display signal convolves with the display screen to produce a viewable image having reduced artifacts. A relatively fixed screen map is produced during a calibration routine. The screen map is updated dynamically during a display session. <CIT> discloses a display apparatus including a display section that includes a light source and displays a displayed image based on image data and an image correction section that corrects the image data based on correction data. The image correction section corrects a color in the image by switching the correction data between first correction data which enables correction in which a displayed color in the displayed image conforms to a reference color and second correction data which enables correction in which a displayed color in the displayed image conforms to a color within an allowable range set in advance. <CIT> discloses a projection display including a highlight projector and a main projector. Highlights projected by the highlight projector boost luminance in highlight areas of a base image projected by the main projector. Various highlight projectors including steerable beams, holographic projectors and spatial light modulators are described. <CIT> is a document under Art. <NUM>(<NUM>) EPC and discloses a projection system and an image uniformity compensation method thereof are provided. A test image is projected onto a projection surface by a projection device. When the test image is projected, a plurality of color measurement devices is used to perform measurement on the projection surface to acquire a plurality of test color data corresponding to a plurality of measurement positions respectively. An estimated image is established by using the plurality of test color data. Uniformity compensation information of each pixel is updated according to a target value and each piece of pixel information of the estimated image. An initial image is compensated according to the uniformity compensation information to generate a uniform image, which is then projected by the projection device.

Various aspects of the present disclosure relate to devices, systems, and methods for uniformity correction of a displayed image.

In one exemplary aspect of the present disclosure, there is provided a projection system comprising a controller; a light source configured to emit a light in response to an image signal provided by the controller, wherein the image signal includes image data corresponding to a plurality of frame to be successively displayed; an optical system configured to project the light emitted by the light source, and the controller configured to: receive an input associated with a plurality of light values corresponding to a plurality of primary lightfields, wherein the plurality of lightfields includes red, green and blue primary lightfields, and wherein the plurality of light values includes a value of a red primary lightfield, a value of a green primary lightfield and a value of a blue primary lightfield at each pixel of an image frame, and wherein the input associated with the plurality of light values is a picture of a first image taken by a camera; convert the input associated with the plurality of light values to a plurality of projector primary color values, wherein the plurality of projector primary color values corresponds to actual light values output by the projection system for the first image, including errors; determine a gain map for uniformity correction based on the plurality of projector primary color values, apply the gain map to an image to perform a chromaticity uniformity correction by adjusting levels of the plurality of primary lightfields so that a primary mixture is the same over an image frame, and project the image with the optical system in the image frame, wherein a second image is corrected by the gain map.

In another exemplary aspect of the present disclosure, there is provided a method of correcting an image provided by a light source configured to emit a light in response to an image signal provided by a controller, wherein the image signal includes image data corresponding to a plurality of frames to be successively displayed; and an optical system configured to project the light emitted by the light source, the method comprising: receiving an input associated with a plurality of light values corresponding to a plurality of primary lightfields, wherein the plurality of primary lightfields includes red, green, and blue primary lightfields, and wherein the plurality of light values include a value of a red primary lightfield, a value of a green primary lightfield and a value of a blue primary lightfield at each pixel of an image frame, and wherein the input associated with the plurality of light values is a picture of a first image taken by a camera, converting the input associated with the plurality of light values to a plurality of projector primary color values, wherein the plurality of projector primary color values corresponds to actual light values output by the projection system for the first image, including errors, determining a gain map for uniformity correction based on the plurality of projector primary color values, applying the gain map to an image to perform a chromaticity uniformity correction by adjusting levels of the plurality of primary lightfields so that a primary mixture is the same over an image frame, and projecting the image with the optical system in the image frame, wherein a second image is corrected by the gain map.

In another exemplary aspect of the present disclosure, there is provided a non-transitory computer-readable medium storing instructions that, when executed by a processor of a projection system including a light source configured to emit a light in response to an image data and an optical system configured to project the light emitted by the light source, cause the projection device to perform operations comprising receiving an input associated with a plurality of light values corresponding to a plurality of primary lightfields, converting the input associated with the plurality of light values to a plurality of projector primary color values, determining a gain map based on the plurality of projector primary color values, applying the gain map to an image to perform a chromaticity uniformity correction by adjusting levels of the plurality of primary lightfields so that a primary mixture is the same over an image frame, and projecting the image with the optical system in the image frame, wherein the second image is corrected by the gain map.

In this manner, various aspects of the present disclosure provide for the display of images having a high dynamic range and high resolution, and effect improvements in at least the technical fields of image projection, holography, signal processing, and the like.

These and other more detailed and specific features of various embodiments are more fully disclosed in the following description, reference being had to the accompanying drawings, in which:.

This disclosure and aspects thereof can be embodied in various forms, including hardware, devices, or circuits controlled by computer-implemented methods, computer program products, computer systems and networks, user interfaces, and application programming interfaces; as well as hardware-implemented methods, signal processing circuits, memory arrays, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), and the like. The foregoing summary is intended solely to give a general idea of various aspects of the present disclosure, and does not limit the scope of the invention which is defined by the appended claims.

In the following description, numerous details are set forth, such as optical device configurations, timings, operations, and the like, in order to provide an understanding of one or more aspects of the present disclosure. It will be readily apparent to one skilled in the art that these specific details are merely exemplary and not intended to limit the scope of this application.

Moreover, while the present disclosure focuses mainly on examples in which the various circuits are used in digital projection systems, it will be understood that this is merely one example of an implementation. It will further be understood that the disclosed systems and methods can be used in any device in which there is a need to project light; for example, cinema, consumer, and other commercial projection systems, heads-up displays, virtual reality displays, and the like. Disclosed systems and methods may be implemented in additional display devices, such as with an OLED display, an LCD display, a quantum dot display, or the like.

As previously described, image uniformity can be categorized into chromaticity uniformity and luminance uniformity. Chromaticity uniformity is a measure of the variation of chromaticity over the image frame (i.e., the full frame of pixels that create an image) without consideration of the absolute chromaticity of the desired color. Chromaticity uniformity may be measured by comparing the chromaticity of the image to that of the desired color.

Luminance uniformity is a measure of how well the luminance over the image frame conforms to a prescribed luminance profile. While the luminance profile may not be flat, a uniform luminance may be smooth and symmetrical about the center of the image, albeit brighter in the center. Luminance uniformity may not consider the absolute luminance of the desired color, but rather the luminance profile. The luminance uniformity may be measured by comparing the luminance of the image to that of the desired color. If the luminance profile is not flat, the luminance should match at the image center.

Variations in luminance uniformity and chromaticity uniformity may not be equally perceived by the eyes of a viewer of the projected image. Luminance uniformity errors may be very large without being visibly objectionable, and may in some cases be ignored. Chromaticity uniformity errors, however, are easily noticed. For example, for a white flat-field image, if the chromaticity is uniform and the luminance smoothly deviates from the luminance profile by between <NUM>% and <NUM>%, the probability of an observer noticing the luminance error is low. However, if chromaticity has each of the color primaries varying from each other by between <NUM>% and <NUM>%, the chromaticity error is more easily noticeable.

These deviations in chromaticity and luminance across the image frame occur due to the projector having physical components with non-ideal behavior, which may be caused by manufacturing tolerances, wear and tear on projector components, thermal effects, bent cables, and the like. For example, when a flat white image is applied as input with no uniformity correction, the screen shows raw primary lightfields. To display flat white images, the primary lightfields may be fully driven at their maximum power. Accordingly, uniformity correction of a white image involves reducing light in areas of the primary lightfields. A high peak level of the primary lightfields is desirable, so uniformity correction should minimize any reduction in luminance.

Chromaticity uniformity correction adjusts the levels of the primary lightfields themselves, such that the primary mixture of the primary lightfields is the same over the entire image frame. For example, when the primary lightfields are red, green, and blue (i.e., an RGB primary), white is displayed as (R, G, B) = (<NUM>, <NUM>, <NUM>), where <NUM> is a maximum value for each lightfield. The primary lightfields should be adjusted so that each point on the image frame is reduced to the minimum value of the three primary lightfields, resulting in chromaticity uniformity with minimum total light loss. Performing this operation on a white screen may correct uniformity error in all flat-field images other than white for the projection system. However, in a situation where a primary lightfield has such a low level that the chromaticity correction causes an unacceptably low light output, the display may be considered defective.

If a chromaticity uniformity correction is already applied, a luminance uniformity correction adjusts all primary lightfields by the same amounts, as each primary lightfield has the same level map or shape. However, this shape may not match the prescribed luminance profile, and attempting to match the prescribed luminance profile involves reducing the light level of each of the primary lightfields. Accordingly, luminance uniformity may only be applied if the non-uniformity is visible to an observer, or the display must conform to a standard specification for uniformity.

Chromaticity correction benefits from a target luminance profile at which all primary lightfields conform. If any one or the raw primary lightfields is not smooth, a target luminance profile that is the minimum of the three lightfields may also not be smooth. A chromaticity uniformity correction targeting a non-smooth luminance profile would create a luminance non-uniformity that may be visible. To prevent this, a smooth lower-bound of the minimum of the primary lightfields is used as the target luminance profile. If a luminance uniformity correction is included in the target luminance profile, the same smoothing constraint may be used. The various correction operations described herein may be implemented by the projector as will be described in more detail below.

<FIG> illustrates an exemplary high contrast projection system <NUM> according to various aspects of the present disclosure. In particular, <FIG> illustrates a projection system <NUM> which includes a light source <NUM> configured to emit a first light <NUM>; illumination optics <NUM> (one example of an illumination optical system in accordance with the present disclosure) configured to receive the first light <NUM> and redirect, steer or otherwise modify it, thereby to generate a second light <NUM> (i.e., a steered light); a DMD <NUM> configured to receive the second light <NUM> and selectively redirect and/or modulate it as a third light <NUM> (i.e., a modulated light); first projection optics <NUM> configured to receive the third light <NUM> and project it as a fourth light <NUM>; a filter <NUM> configured to filter the fourth light <NUM>, thereby to generate a fifth light <NUM>; and second projection optics <NUM> configured to receive the fifth light <NUM> and project it as a sixth light <NUM> onto a screen <NUM>.

In practical implementations, the projection system <NUM> may include fewer optical components or may include additional optical components such as mirrors, lenses, waveguides, optical fibers, beam splitters, diffusers, and the like. With the exception of the screen <NUM>, the components illustrated in <FIG> may, in one implementation, be integrated into a housing to provide a projection device. In other implementations, the projection system <NUM> may include multiple housings. For example, the light source <NUM>, the illumination optics <NUM>, and the DMD <NUM> may be provided in a first housing, and the first projection optics <NUM>, the filter <NUM>, and the second projection optics <NUM> may be provided in a second housing which may be mated with the first housing. In some further implementations, one or more of the housings may themselves include subassemblies. The one or more housings of such a projection device may include additional components such as a memory, input/output ports, communication circuitry, a power supply, and the like.

The light source <NUM> may be, for example, a laser light source, an LED, and the like. Generally, the light source <NUM> is any light emitter which emits light. In some implementations, the light is coherent light. In some aspects of the present disclosure, the light source <NUM> may comprise multiple individual light emitters, each corresponding to a different wavelength or wavelength band. The light source <NUM> emits light in response to an image signal provided by the controller <NUM>; for example, one or more processors such as a central processing unit (CPU) of the projection system <NUM>. The image signal includes image data corresponding to a plurality of frames to be successively displayed. Individual elements in the projection system <NUM>, including the DMD <NUM>, may be controlled by the controller <NUM>. While not particularly illustrated in <FIG>, the controller <NUM> may additionally or alternatively control the illumination optics <NUM>, the first projection optics <NUM>, and the second projection optics <NUM>. The image signal may originate from an external source in a streaming or cloud-based manner, may originate from an internal memory of the projection system <NUM> such as a hard disk, may originate from a removable medium that is operatively connected to the projection system <NUM>, or combinations thereof.

Although <FIG> illustrates a generally linear optical path, in practice the optical path is generally more complex. For example, in the projection system <NUM>, the second light <NUM> from the illumination optics <NUM> is steered to the DMD chip <NUM> (or chips) at an oblique angle.

To illustrate the effects of the angle of incidence and the DMD mirrors, <FIG> show an exemplary DMD <NUM> in accordance with various aspects of the present disclosure. In particular, <FIG> illustrates a plan view of the DMD <NUM>, and <FIG> illustrates partial cross-sectional view of the DMD <NUM> taken along line II-B illustrated in <FIG>. The DMD <NUM> includes a plurality of square micromirrors <NUM> arranged in a two-dimensional rectangular array on a substrate <NUM>. In some examples, the DMD <NUM> may be a digital light processor (DLP) from Texas Instruments. Each micromirror <NUM> may correspond to one pixel of the eventual projection image, and may be configured to tilt about a rotation axis <NUM>, shown for one particular subset of the micromirrors <NUM>, by electrostatic or other actuation. The individual micromirrors <NUM> have a width <NUM> and are arranged with gaps of width <NUM> therebetween. The micromirrors <NUM> may be formed of or coated with any highly reflective material, such as aluminum or silver, to thereby specularly reflect light. The gaps between the micromirrors <NUM> may be absorptive, such that input light which enters a gap is absorbed by the substrate <NUM>.

While <FIG> expressly shows only some representative micromirrors <NUM>, in practice the DMD <NUM> may include many more individual micromirrors in a number equal to a resolution of the projection system <NUM>. In some examples, the resolution may be <NUM> (<NUM>×<NUM>), <NUM> (<NUM>×<NUM>), 1080p (<NUM>×<NUM>), consumer <NUM> (<NUM>×<NUM>), and the like. Moreover, in some examples the micromirrors <NUM> may be rectangular and arranged in the rectangular array; hexagonal and arranged in a hexagonal array, and the like. Moreover, while <FIG> illustrates the rotation axis <NUM> extending in an oblique direction, in some implementations the rotation axis <NUM> may extend vertically or horizontally.

As can be seen in <FIG>, each micromirror <NUM> may be connected to the substrate <NUM> by a yoke <NUM>, which is rotatably connected to the micromirror <NUM>. The substrate <NUM> includes a plurality of electrodes <NUM>. While only two electrodes <NUM> per micromirror <NUM> are visible in the cross-sectional view of <FIG>, each micromirror <NUM> may in practice include additional electrodes. While not particularly illustrated in <FIG>, the DMD <NUM> may further include spacer layers, support layers, hinge components to control the height or orientation of the micromirror <NUM>, and the like. The substrate <NUM> may include electronic circuitry associated with the DMD <NUM>, such as CMOS transistors, memory elements, and the like.

Depending on the particular operation and control of the electrodes <NUM>, the individual micromirrors <NUM> may be switched between an "on" position, an "off' position, and an unactuated or neutral position. If a micromirror <NUM> is in the on position, it is actuated to an angle of (for example) -<NUM>° (that is, rotated counterclockwise by <NUM>° relative to the neutral position) to specularly reflect input light <NUM> into on-state light <NUM>. If a micromirror <NUM> is in the off position, it is actuated to an angle of (for example) +<NUM>° (that is, rotated clockwise by <NUM>° relative to the neutral position) to specularly reflect the input light <NUM> into off-state light <NUM>. The off-state light <NUM> may be directed toward a light dump that absorbs the off-state light <NUM>. In some instances, a micromirror <NUM> may be unactuated and lie parallel to the substrate <NUM>. The particular angles illustrated in <FIG> and described here are merely exemplary and not limiting. In some implementations, the on- and off-position angles may be between ±<NUM> and ±<NUM> degrees (inclusive), respectively.

In the context of <FIG>, where the DMD mirrors use an angle tilt of <NUM>° to reflect or discard light, the second light <NUM> is steered to the DMD chip <NUM> at a fixed angle of <NUM>°. When an individual mirror is tilted at a first predetermined angle (e.g., -<NUM>°), the mirror is considered to be in the on state and redirects light toward the first projection optics <NUM>, the filter <NUM>, and the second projection optics <NUM> (e.g., a predetermined location). When an individual mirror is tilted at a second predetermined angle (e.g., +<NUM>°), the mirror is considered to be in the off state and redirects light to a light dump located outside the active image area.

In order to ensure the image on the screen <NUM> has an acceptable clarity and has chromaticity and uniformity correction across the image frame, the controller <NUM> may be calibrated and/or configured to provide a uniformity correction to image data provided to the light source <NUM>.

<FIG> illustrates an exemplary uniformity correction method, which may be performed during the calibration of the projection system <NUM> illustrated in <FIG>. The correction method of <FIG> may be performed in an automated manner, for example, through a computer program as will be described in more detail below.

At operation <NUM>, the correction method receives an input associated with a plurality of light values. The plurality of light values correspond to, or are associated with, a plurality of primary lightfields. The plurality of light values include a value of a red lightfield at each point (e.g., each pixel) of the image frame, a value of a green lightfield at each point of the image frame, and a value of a blue lightfield at each point of the image frame.

According to the invention, the input associated with the plurality of light values of the first image is a picture of a first image taken by a camera. For example, a first image is projected with the optical system in an image frame. The first image may be a white image composed of the plurality of primary lightfields, such as red, green, and blue. The first image may include chromaticity errors, such as chroma tinting along the edges of the image frame. <FIG> provide example lightfields of the first image. <FIG> provides an uncorrected red lightfield of the white image, <FIG> provides an uncorrected green lightfield of the white image, and <FIG> provides an uncorrected blue lightfield of the white image.

As can be seen in <FIG>, the contour of the uncorrected red lightfield at one corner, represented as (<NUM>, <NUM>), is lower than the corresponding contour corner of the uncorrected green lightfield in <FIG> and the uncorrected blue lightfield in <FIG>. This means that the red uncorrected lightfield has a lower luminance value at (<NUM>, <NUM>) than the green uncorrected lightfield and the blue uncorrected lightfield at (<NUM>, <NUM>). Similarly, the contour of the uncorrected red lightfield at (<NUM>, <NUM>) is greater than the corresponding contour of the uncorrected green lightfield and the uncorrected blue lightfield. This means that the red uncorrected lightfield has a greater luminance value at (<NUM>, <NUM>) than the green uncorrected lightfield and the blue uncorrected lightfield at (<NUM>, <NUM>).

The camera acts as a colorimeter that measures the R, G, and B values of the first image projected by the projection system <NUM>, as the camera image (e.g., the input associated with the plurality of light values) provides a measured R, G, and B value at each point in the image frame. However, these values may be linearly transformed from the real values projected by the projection system <NUM>. At operation <NUM>, the correction method converts the input to a plurality of projector primary color values. This conversion provides the actual light values of the plurality of lightfields projected by the projector <NUM> and included in the first image.

At operation <NUM>, the correction method determines a gain map based on the plurality of projector primary color values. For example, when the first image projected by the projection system <NUM> is a white image, the R, G, and B values are each set to a maximum. However, the maximum of each value may differ slightly due to deficiencies in manufacturing and/or calibration, or non-ideal behavior in the physical components. These may result in chroma tinting or other chromaticity and luminance errors in the first image. The projector primary color values provide the actual values the projection system <NUM> outputs for the first image, including the error.

If each of the plurality of primary lightfields is at a maximum, uniformity may be achieved by lowering each R, G, and B value to a minimum of the primary lightfields. Accordingly, a level of the red primary lightfield, a level of the green primary lightfield, and a level of the blue primary lightfield are respectively adjusted so that for each point in the image frame, the respective levels are reduced to the minimum of the levels for each point. The gain map provides a map showing how much adjustment should occur at each point in the image frame to achieve uniformity. <FIG>, for example, provides a red chromaticity correction for the uncorrected red lightfield of <FIG>. <FIG> provides a green chromaticity correction for the uncorrected green lightfield of <FIG>. <FIG> provides a blue chromaticity correction for the uncorrected blue lightfield of <FIG>.

As seen in <FIG>, the level of the green lightfield (e.g., the light value) at (<NUM>, <NUM>) is multiplied by <NUM> to reduce the level. This reduction brings the level of the green lightfield down to the level of the red lightfield at (<NUM>, <NUM>). In <FIG>, a similar amount of reduction is applied to the blue lightfield to bring the level of the blue lightfield down to the level of the red lightfield at (<NUM>, <NUM>). Similarly, as illustrated in <FIG>, the level of the red lightfield at (<NUM>, <NUM>) is multiplied by <NUM> to reduce the level of the red lightfield to that of the green lightfield at (<NUM>, <NUM>).

At operation <NUM>, the correction method applies the gain map to an image to perform a chromaticity uniformity correction. For example, the gain maps of <FIG> are applied to the uncorrected lightfields of <FIG>, respectively. The gain map may be applied to image data by the controller <NUM> prior to the image data being provided to the light source <NUM>. For example, the controller <NUM> modifies the image data provided to the light source <NUM>, and therefore modifies the image projected by the light source <NUM>. The image may be a second image different than the first image. At operation <NUM>, the correction method projects the image with the optical system in the image frame. For example, the image defined by the corrected image data is displayed to a viewer. The second image may have a corrected lightfield, such as that illustrated by <FIG>. The second image may be visually uniform across the image frame. Additionally, the second image may have a luminance profile that is a smooth maximum lower-bound of the plurality of primary lightfields due to applying the gain map and adjusting the levels of the plurality of primary lightfields. By using a smooth maximum lower-bound, a smooth luminance profile is achieved.

As one particular example of the operations of <FIG>, the following pseudocode is presented using a MATLAB-like format:
<IMG>.

In the above pseudocode, imgIn is the input image expressed in display primary levels, and may show uniformity errors; imgGain is a gain image used to apply the uniformity correction; imgShow is the image used to drive the display device; imgCapture is the displayed image captured by a camera and converted to display primary levels; imgTarget is the level image that the R, G, and B images will conform to after correction; TakeAndConvertPictureQ is a function that takes a picture of the display image and converts it to display primary levels; minRGB() is a function that takes an RGB image and returns a monochrome image with each pixel the minimum of R, G, and B at that pixel; and Smooth() is a function that smooths an image enough to remove unwanted higher spatial variations in luminance.

The operations described herein may be implemented as instructions or code stored on non-transitory computer-readable medium, such as a hard disk or other storage medium contained in or associated with the projection system <NUM> (e.g., a memory of the controller <NUM>).

The above projection systems and methods may provide for correcting uniformity errors in an image frame. Systems, methods, and devices in accordance with the present disclosure may take any one or more of the following configurations.

With regard to the processes, systems, methods, heuristics, etc. described herein, it should be understood that, although the steps of such processes, etc. have been described as occurring according to a certain ordered sequence, such processes could be practiced with the described steps performed in an order other than the order described herein. It further should be understood that certain steps could be performed simultaneously, that other steps could be added, or that certain steps described herein could be omitted. In other words, the descriptions of processes herein are provided for the purpose of illustrating certain embodiments, and should in no way be construed so as to limit the claims.

Accordingly, it is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be apparent upon reading the above description. The scope should be determined, not with reference to the above description, but should instead be determined with reference to the appended claims.

All terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those knowledgeable in the technologies described herein unless an explicit indication to the contrary in made herein. In particular, use of the singular articles such as "a," "the," "said," etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.

Claim 1:
A projection system, comprising:
a controller;
a light source configured to emit a light in response to an image signal provided by the controller, wherein the image signal includes image data corresponding to a plurality of frames to be successively displayed; and
an optical system configured to project the light emitted by the light source; and
wherein the controller is configured to:
receive an input associated with a plurality of light values corresponding to a plurality of primary lightfields, wherein the plurality of primary lightfields includes red, green, and blue primary lightfields, and wherein the plurality of light values includes a value of a red primary lightfield, a value of a green primary lightfield and a value of a blue primary lightfield at each pixel of an image frame, and wherein the input associated with the plurality of light values is a picture of a first image taken by a camera;
convert the input associated with the plurality of light values to a plurality of projector primary color values, wherein the plurality of projector primary color values corresponds to actual light values output by the projection system for the first image, including errors;
determine a gain map for a chromaticity uniformity correction based on the plurality of projector primary color values;
apply the gain map to an image to perform the chromaticity uniformity correction by adjusting levels of the plurality of primary lightfields so that a primary mixture is the same over an image frame; and
project the image with the optical system in the image frame, wherein a second image is corrected by the gain map.