JP2010521098A - True color communication - Google Patents

Abstract

Embodiments of the present invention describe systems and methods for communicating the true color of a subject. In one embodiment, the present invention provides an image capture device 201, an imaging reference color set 202 that includes at least one reference color 202a, and a control reference that includes at least one control color 203a corresponding to the at least one reference color 203a. A color set 203 is provided. The present invention accesses the control reference color set and imaging reference color set 202 to generate a color correction function 210 that eliminates the difference between at least one reference color 203a and at least one control color 203a. A component 204 is further provided.
[Selection] Figure 1

Description

  Embodiments of the present invention relate to accurately capturing and transmitting the color of a subject.

In the technical field of image capture and image reproduction, processing parameters of the image capture device and the image display device are preset by the manufacturer.
Typically, the manufacturer adjusts these parameters so that the created image looks “good” so that the user is satisfied with the result.
This is called a “photofinishing or preferred reproduction model” as opposed to a “colorimetric reproduction model” that attempts to convey the exact color of the subject.
For example, many digital cameras are referred to as “white balance”, which adjusts the imaging parameters so that the overall average color of the image is, for example, the color of a half-brightness gray image (50% gray). Perform the operation. This assumes that the view being imaged is actually 50% gray, which is rarely the case.
Thus, white balance is an arbitrary adjustment that functions qualitatively to produce an observable image but does not function quantitatively to produce an accurately rendered image.

In an exemplary white balance process, the darkest and brightest drawing values (eg, black level and white level) in an image are typically clipped by analysis of the distribution of observed brightness levels.
This clipping is done to ensure full use of the available signal range.
For example, pre-specified percentages of dark and light values are clipped and mapped to the same value (eg, zero or maximum value).
The intermediate value is then scaled over the available range.
However, this scaling may distort the true color spectrum to make the resulting image more attractive.
These adjustments are typically predefined by the manufacturer and applied uniformly to all of the acquired images.
Thus, digital camera processing parameters do not address rendering the “true” color of items in the view, because the “true” color of items in the view cannot be determined without other information. .

In addition, ambient lighting conditions that are present when an image is captured can distort the overall color scheme of the image.
For example, if a photograph is taken indoors, the light emitted by the luminaire may be biased to a specific range of color spectrum.
For example, fluorescent lighting emits light having a slightly bluish hue.
Therefore, a photograph taken in the presence of fluorescent lighting is distorted by the ambient light and draws a subject with a tone that is bluer than a tone that may actually exist.

In order to overcome these distortions, a controlled environment may be provided in which the image processing parameters of the image capture device are carefully calibrated and monitored.
These controlled environments also rely on carefully calibrated and controlled lighting so that any distortion generated by the ambient lighting and image processing equipment is known or minimized.

In addition to the problem of capturing photometrically accurate images, displaying images without introducing color space distortion is also a problem.
For example, the color reproduction of a computer monitor or other display device changes over time.
As a result, the displayed color values may have some “drift” from the preset calibration parameters over time.
In applications where it is important that color rendering must remain consistent (eg, computer animation), detailed analysis and recalibration of the computer monitor is occasionally required.
Similarly, printers are calibrated before sale, but online calibration is typically limited to on / off testing of nozzle function.
Scanners can be used to perform color calibration or recalibration, but they combine inaccuracies that can arise from both image printing and scanning.

Embodiments of the present invention describe systems and methods for communicating the true color of a subject. In one embodiment, the invention comprises an image capture device, an imaging reference color set that includes at least one reference color, and a control reference color set that includes at least one control color corresponding to the at least one reference color.
The present invention further comprises a color correction component for accessing the control reference color set and the imaging reference color set to generate a color correction function that removes the difference between the at least one reference color and the at least one control color. .

  The accompanying drawings are incorporated in and constitute a part of this specification. The accompanying drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. Unless otherwise stated, it is to be understood that the drawings referred to in this specification are not drawn to scale.

3 is a flowchart of a method for transmitting a true color of a subject according to an embodiment of the present invention; 1 illustrates an exemplary image capture system used in accordance with an embodiment of the present invention. 1 illustrates an exemplary image capture system used in accordance with an embodiment of the present invention. 1 illustrates an exemplary image capture system used in accordance with an embodiment of the present invention. 2 illustrates an exemplary color reference set used in embodiments of the present invention. FIG. 3 is a block diagram of a color correction component according to an embodiment of the present invention. FIG. 2 is a block diagram of an exemplary computer system that can implement embodiments of the present invention.

  Reference will now be made in detail to embodiments of the present invention. Examples of embodiments of the invention are illustrated in the accompanying drawings. While the invention will be described in conjunction with the following embodiments, it will be understood that the embodiments are not intended to limit the invention to these embodiments only. On the contrary, the invention is intended to cover alternatives, modifications, and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, embodiments of the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present invention.

Notation and Terminology Some portions of the detailed description that follows are presented in terms of procedures, logic blocks, processing, and other symbolic representations of data bits in computer memory.
These descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art.
In this application, a procedure, logic block, process, etc. is considered to be a self-consistent sequence of steps or instructions that yields the desired result.
These steps are those requiring physical manipulation of physical quantities.
Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated in a computer system.

On the other hand, it should be noted that all of these and similar terms are associated with the appropriate physical quantities and are merely convenient labels applied to these quantities.
Throughout the present invention, “access”, “generate”, “apply”, “concatenate”, “use”, “identify”, “store”, “generate” unless otherwise specified as clear from the following discussion It is understood that discussions using terms such as “capture”, etc., refer to operations and processes of a computer system or similar electronic computing device.
The computer system or similar electronic computing device manipulates data represented as physical (electronic) quantities in the computer system's registers and memory to provide the computer system's memory or register or other such information storage device, Similarly, the data is converted into other data represented as a physical quantity in the transmission device or the display device.

FIG. 1 is a flowchart of a method 100 for transmitting true color of a subject according to an embodiment of the present invention.
In step 110 of FIG. 1, an imaging reference color set including at least one reference color is accessed. In an embodiment of the invention, an image including a set of reference colors is captured. The imaging reference color set may be the only object in the captured image, or may be present in the captured image of the subject.
In an embodiment of the present invention, the subject can be any person, place, or object from which the image can be captured.

Usually, the quality and spectral characteristics of the light hitting a given subject will affect the appearance of the subject relative to the camera, and thus the subject's appearance in the image generated by the camera.
The camera itself introduces further alterations in the perceived color scheme of the subject through the physical characteristics of the sensor's design and manufacture, and also through the camera's internal processing characteristics.
These effects, combined, make the color metric of the imaged subject very suspicious.
By observing a set of reference colors captured with essentially the same ambient lighting conditions and processing parameters as the image of the subject, embodiments of the present invention derive from the observed color space of the captured image and the ambient lighting conditions and It can be facilitated to seek conversion to a reference color space or “true” color space independent of the image processing capabilities of the camera that captures the image.

In step 120 of FIG. 1, a control reference color set that includes at least one control color corresponding to at least one reference color is accessed.
In an embodiment of the present invention, a true color space is represented by a control reference color set that includes one or more colors that match one or more colors of the imaging reference color set.
It will be understood that the control reference color set may include a logical reference color set from which the spectral reflection and color signal values of the reference color set in the captured image are accessed, rather than the actual physical entity.

In step 130 of FIG. 1, a color correction function is generated that eliminates the difference between at least one reference color and the corresponding control color.
By comparing the characteristics of the control reference color set with the characteristics of the imaging reference color set captured in the image, an embodiment of the present invention can be used between the characteristics of the imaging reference color set and the characteristics of the control reference color set. Thus, a conversion that takes into account these differences, that is, a “color correction function” can be obtained.
This color correction function directly compensates for the combined effects of room ambient lighting and acquisition camera color conversion.

To facilitate determining this reference transformation, embodiments of the present invention detect an imaging reference color set in the image and measure an observed characteristic of the imaging reference color set.
Embodiments of the present invention then determine a color correction function that approximates the color description of the imaging reference color set to the color values of the control reference color set.
This color correction function can then be applied to the captured image. That is, this color correction function can then be applied to the captured image so that the color in the image more accurately conveys the true color of the subject.

Thus, embodiments of the present invention can infer the combined effects of ambient lighting conditions at the location where an image is captured and the device characteristics and image processing capabilities of the image capture system.
These combined effects are then substantially removed from the image so that a more accurate representation of the subject's color can be conveyed.
In embodiments of the present invention, the color correction function can be generated and applied by the image capture device itself, can be generated and applied by a device that displays the image, can be generated and applied as a service by a third party, Any combination of these can also be used.

FIG. 2A illustrates an exemplary image capture system 200 used with embodiments of the present invention.
In an embodiment of the present invention, the system 200 includes an image capture device 201, an imaging reference color set 202, a control reference color set 203, and a color correction component 204.
In the embodiment of FIG. 2A, the imaging reference color set 202 further comprises at least one reference color 202a and unique identification information 202b.
Further, the control reference color set 203 further includes at least one control color 203a that matches at least one reference color 202a, and corresponding identification information 203b that matches the unique identification information 202b.

In an embodiment of the present invention, the color correction component 204 is for accessing the imaging reference color set 202 and the control reference color set 203.
More specifically, the color correction component 204 compares the reference color 202a with the control color 203a so that the colors in the imaging reference color set 202 are due to ambient lighting conditions and image processing parameters of the image capture device 201. Judge how it was converted.
The color correction component 204 then generates a color correction function (eg, 210) that removes the difference if there is a difference between the reference color 202a and the control color 203a.

In an embodiment of the present invention, the system 200 further comprises an applicator 205 that is coupled to the color correction component 204.
In an embodiment of the invention, the applicator 205 applies the color correction function 210 generated by the color correction component 204 to an image (eg, 206) to create a modified image 207.
In so doing, the combined effects of the ambient lighting conditions at the location where the image 206 was captured and the device characteristics and image processing capabilities of the image capture device 201 are removed from the modified image 207.
As a result, the true color of the subject (for example, 211) is transmitted in the corrected image 207.
For the purposes of the present invention, the term “removed” means that the difference between the reference color of the imaging reference color set 202 (eg, of the modified image 207) and the control reference color set 203 is outside the detection parameters of the system 200. Note that it is either within or within an acceptable variation.

As described above, in the embodiments of the present invention, the imaging reference color set 202 may be captured in the same image 206 as the subject 211.
In another embodiment, the imaging reference color set 202 may be captured in an image that is separate from the image 206 from which the subject 211 is captured.
This can be advantageous in situations where it may not be desired to show the imaging reference color set 202 in the same image as the subject 211.
For example, in a studio photography session, a cameraman may not want the imaging reference color set 202 to appear as a portrait of the subject 211.
Accordingly, the photographer may capture a first image of the imaging reference color set 202 that is used in determining the color correction function 210.
Thereafter, the captured image of the subject 211 is processed using the color correction function 210 generated in advance by the color correction component 204.
In one embodiment, the system 200 further comprises a data storage device 208 for storing the color correction function 210 and one or more images (eg, image 206, modified image 207, etc.).
It should be noted that in embodiments of the present invention, the ambient lighting conditions and the image processing ability to capture separate images should be substantially the same to derive an accurate color correction function 210.

Note that the configuration of system 200 of FIG. 2A is exemplary, and that other configurations of components are possible in accordance with embodiments of the present invention.
For example, the color correction component 204, the applicator 205, and the data storage device 208 can be implemented as separate color correction systems or as a network of communicatively coupled components.
In an embodiment of the present invention, the functionality of the color correction component 204, the functionality of the applicator 205, and the functionality of the data storage device 208 may be implemented as a service by a third party service provider or network 209 provider.
Alternatively, the color correction component 204, the applicator 205, and the data storage device 208 can be implemented as components of the image capture device 201.
In another embodiment, applicator 205 is located on image capture device 201 that is communicatively coupled to color correction component 204 and data storage device 208.
Therefore, the image capture device 201 receives the color correction function 210 via the network 209 and applies it to the image 207 to create a corrected image 207.
In another embodiment, the color correction component 204, applicator 205, and control reference color set 203 use removable media such as a smart card or other removable data storage (eg, in the image capture device 201). It can be implemented as a removable component.

In an embodiment of the present invention, image capture device 201 does not require a controlled infrastructure when capturing image 206.
For example, the image capture device 201 can be a personal computer system of a subject, a digital camera, or a mobile phone (eg, referred to herein as “picture phone”) that can generate a photograph.
Thus, embodiments of the present invention can capture the image 206 using the subject's personal equipment rather than relying on calibrated equipment (eg, calibrated camera and calibrated lighting).
Further, as long as the ambient lighting conditions are sufficient for processing the image of the color correction component 204, it is not necessary to capture the image 206 in an environment where the ambient lighting conditions are known or controlled.
As a result, the image 206 can be captured even in various environments including, for example, the outdoors or the home of the subject 211.

Since the color correction component 204 uses the received image of the imaging reference color set 202 to infer ambient lighting conditions and image processing parameters of the image capture device 201, embodiments of the present invention provide a controlled infrastructure. This is advantageous in that it is not necessary.
For example, the color correction component 204 can compare the color description of the color that includes the imaging reference color set 202 with the color description of the corresponding color from the control reference color set 208. As a result, embodiments of the present invention do not rely on calibrated cameras or calibrated lighting when capturing images of the subject 211.
By performing this analysis, the color correction component 204 can infer the combined influence of the ambient lighting conditions of the location where the subject 211 is located and the image processing capability of the image capture device 201.
The color correction component 204 then adjusts what the received spectral reflection and color signal values of the imaging reference color set 202 match the known spectral reflection and color signal values of the control reference color set 203. Can be determined.
The color correction component 204 can therefore compensate for the image distortion induced by the ambient lighting conditions when the image was captured and the image processing parameters of the image capture device 201, and based on this analysis, draws the subject 211. You can guess the exact color to do.
Although the present invention describes that a controlled infrastructure is not required, embodiments of the present invention may be used with a controlled infrastructure.

In an embodiment of the present invention, the image capture device 201 is a subject 211 such as a printer, scanner, picture phone, digital camera, personal information terminal (PDA), personal computer system, digital video recorder, or similar device capable of capturing images. Of personal property.
However, embodiments of the present invention may also be used in a unique system where a manufacturer establishes a store or other automated system for providing product consultation.

In embodiments of the present invention, network 209 includes a dial-up Internet connection, a public switched telephone network (PSTN), a high speed network connection (eg, cable Internet or high speed computer network), and the like.
Alternatively, the image capture device 201 may utilize a cellular phone connection, satellite phone connection, wireless connection, infrared communication connection, or other type of wireless communication.

In the embodiment of the present invention, accurately presenting the true color to the observer is as important as capturing the true color of the subject 211.
Thus, embodiments of the present invention can be used to adjust the display so that the color indicated by the display is as desired.
In other words, removing the color distortion generated by the display device is also important in transmitting the true color of the subject.
In an embodiment of the present invention, the data accessed by the display may be considered “raw” data that has not yet been processed as described above with reference to FIG. 2A.
In another embodiment, the data accessed by the display may be considered “processed” data that has been processed as described above with reference to FIG. 2A.

Furthermore, it should be noted that embodiments of the present invention are not limited to color correction alone.
For example, in an embodiment of the invention, the color correction component 204 inspects the geometric pattern of the imaging reference color set 202 and the lens of the image capture device 201 introduces a geometric defect into the image 206. It can also be determined whether or not.
If a geometric defect is detected in the image 206, the color correction function may also include a conversion function for correcting this defect in the corrected image 207.

FIG. 2B illustrates another exemplary image capture system used in accordance with an embodiment of the present invention.
In the embodiment of FIG. 2B, the data accessed by the display device can be considered as “processed” data that has been processed as described above with reference to FIG. 2A and represents a “true” color.
In FIG. 2B, the display device 220 generates a display 221. In embodiments of the invention, the display 221 may include a printed display, a projected display, a digitally generated display, and the like.
In FIG. 2B, the imaging reference color set 202 is shown in the display 221 and the physical control reference color set 222 is placed in proximity to the display 221.
Note that the imaging reference color set 202 can include a reference color 202a and unique identification information 202b, as described above with reference to FIG. 2A.
Similarly, the physical control reference color set 222 may further include a physical reference color 222a and corresponding identification information 222b.
The spectral reflection and color signal values of the physical reference color 222a may match the spectral reflection and color signal values of the control reference color set 203 as described above with reference to FIG. 2A.

In an embodiment of the present invention, ambient lighting conditions and image processing parameters of the image capture device 201 may be initially determined prior to processing the imaging reference color set 202 shown in the display 221.
Thus, in one embodiment, the color correction component 204 compares the physical reference color 222a with the control color 203a so that the colors in the imaging reference color set 202 are due to ambient lighting conditions and image processing parameters of the image capture device 201. And find out how it was converted.
The color correction component 204 then determines how the received spectral reflection and color signal values of the physical control reference color set 222 match the known spectral reflection and color signal values of the control reference color set 203. You can ask if you need to adjust.
The color correction component 204 then includes a color correction function 210 that compensates for image distortion induced by ambient lighting conditions or image processing parameters of the image capture device 201 when capturing an image of the physical control reference color set 222. Generate.

As shown in FIG. 2B, the imaging reference color set 202 and the physical control reference color set 222 are then imaged simultaneously by the image capture device 201.
In an embodiment of the present invention, the image 202 is a depiction of the provided control reference color set 203 ′ in “true” color, and the captured image 206 has a color correction function with the imaging reference color set 202 and the control reference. It is conveyed to the color correction component 204 that is generated based on the comparison of the color set 203 ′.
Accordingly, when a difference between the imaging reference color set 202 and the control reference color set 203 ′ is detected by the color correction component 204, the difference between the imaging reference color set 202 and the control reference color set 203 ′. A second color correction function 225 is removed that removes.
As described in more detail below, in embodiments of the present invention, the color correction component 204 or applicator 205 can comprise a color adjustment generator for controlling at least one color control of the display 221.
Thus, in the embodiment of FIG. 2B, the applicator 205 is one of the color controls in the display 221 that removes any difference between the reference color (s) of the imaging reference color set 202 and the control reference color set 203 ′. An adjustment 223 can be generated in response to the second color correction function 225 that causes the change.

In other words, embodiments of the present invention provide a first conversion function (e.g., color correction function 210) between the physical control reference color set 222 and its exact photometric appearance for viewing. Ask for.
A second conversion function (eg, second color correction function 225) between the control reference color set 203 ′ and the imaging reference color set 202 is determined.
The mapping from display to accurate viewing of the image can be determined from an appropriate combination of these two transformations.
The color correction function 210 takes into account the combined effects of illumination and image capture parameters on the observed colors of the physical control reference color set 222. The second color correction function 225 takes into account the combined effects of illumination, display parameters of the display device 220, and image capture parameters.
Therefore, the inverse product process of the color correction function 210 with the second color correction function 225 can be performed to determine the influence of the display parameters of the display device 220.
As a result, the output of the display device 220 can be controlled by the system 200 so that the ambient lighting conditions on the display device 220 and the display processing parameters of the display device 220 do not affect the color representation of the display 221.
In other words, the image displayed by the display device 220 is now independent of the ambient lighting conditions and the image processing capability of the camera that captures the image, and the true color of the subject can be accurately transmitted by the system 200.
It should also be noted that the control reference color set 203 ′ as applied to the display image 202 need not be different from the reference set 203 as applied to the physical control reference color set 222.
They are the same when the data accessed by the display device 220 is the same as the color representation of the physical control reference color set 222 (ie, processed to be 203).

It should be noted that the configuration of system 200 of FIG. 2B is exemplary and other configurations of components are possible according to embodiments of the invention.
As described above, the color correction component 204, applicator 205, and data storage device 208 can be implemented as separate color correction systems or as a network of communicatively coupled components.
In an embodiment of the present invention, the functionality of the color correction component 204, the functionality of the applicator 205, and the functionality of the data storage device 208 may be performed as a service by a third party service provider or network 209 provider.
Alternatively, color correction component 204, applicator 205, and data storage device 208 can be implemented as components of image capture device 201 or display device 220.
This process can be performed once as a calibration step for the display device 220, it can be performed as an iterative or feedback cycle to constantly adjust the color control of the display device 220, and the result of 202 in 221 can be It should be noted that the display can also be made as an adjustment to the accessed color representation of the image 202 so that it is within an acceptable tolerance of the “true” control reference color set 203 ′.

Referring now to FIG. 2C, data accessed by the display device 220 (eg, the modified image 207) matches the control color reference set 203 and matches the “true” color of the physical control reference color set 202. Can be regarded as “composite” data generated in this way.
As shown in FIG. 2C, the corrected image 207 and the imaging reference color set 202 are simultaneously imaged by the image capture device 201. In an embodiment of the present invention, this image 206 is a color correction component in which a color correction function is generated based on a comparison of two reference color sets that can be viewed in the modified image 207, namely the display image 207 and the reference color set 202. It is conveyed to 204.
Accordingly, when a difference between the corrected image 207 and the reference color set 202 is detected by the color correction component 204, a color correction function 225 is generated that removes the difference between the corrected image 207 and the reference color set 202.
As described in more detail below, in embodiments of the present invention, the color correction component 204 or applicator 205 can comprise a color adjustment generator for controlling at least one color control of the display 221.
Thus, in the embodiment of FIG. 2C, the applicator 205 removes any difference between the reference color (s) of the modified image 207 and the reference color (s) of the reference color set 202, which controls the color of the display 221. An adjustment 223 can be generated in response to the second color correction function 225 that causes a change in one of the two.

Since the modified image 207 should represent the “true” color value of the control reference color set 202, any difference between them indicates a distortion of the color shown in the display 221. Thus, in an embodiment of the present invention, the modified image 207 can be used as a reference color set for determining the color correction 225 when shown in the display 221.
A conversion function (eg, color correction function 225) between the imaging reference color set 202 and the displayed image reference color set 207 is determined.
Any difference between these color values indicates distortion of the color representation due to the characteristics of the display device 220.
As a result, the output of the display device 220 can be controlled by the system 200 so that the display processing parameters of the display device 220 do not present deviations from the colors of the reference color set 202 in the color representation of the display 221.
In other words, the image displayed by the display device 220 now matches the desired “true” color set 202.
How true the display matches depends on the display device's gamut, in other words, on its ability to accurately render the desired color.

Again, it should be noted that the configuration of system 200 of FIG. 2C is exemplary, and that other configurations of components are possible according to embodiments of the invention.
As described above, the color correction component 204, applicator 205, and data storage device 208 can be implemented as separate color correction systems or as a network of communicatively coupled components.
In an embodiment of the present invention, the functionality of the color correction component 204, the functionality of the applicator 205, and the functionality of the data storage device 208 may be implemented as a service by a third party service provider or network 209 provider.
Alternatively, color correction component 204, applicator 205, and data storage device 208 can be implemented as components of image capture device 201 or display device 220.
This process can be performed once as a calibration step for display device 220, it can be performed as an iterative or feedback cycle to constantly adjust the color control of display device 220, and the result of 207 in 221 Note that the display can also be made as an adjustment to the accessed color representation of the image 207 such that it is within the acceptable tolerance of the “true” color set 202.

In the embodiment of the invention described in FIGS. 2A, 2B, and 2C, feedback from analysis of the image 206 can be used to adjust internal sensor and actuator settings.
Thus, for example, the image capture device 201 can set its registers (eg, gain, exposure, brightness, black and dark levels, saturation, contrast, etc.) so that the capture of the image result best represents the true color value. ) Can be optimized.
Similarly, the control of the display 220 can be adjusted to optimize the output of the display 221, and given the effects of the system, the presented color can be converted to produce its best display.

FIG. 3 illustrates an exemplary imaging reference color set 202 used in embodiments of the present invention.
The following discussion describes an area of imaging reference color set 202 that includes one or more colors, but it is noted that these colors have been omitted from FIG. 3 for clarity. I want.
In an embodiment of the present invention, the imaging reference color set 202 is designed for robust automatic detection by the color correction component 204.

As shown in FIG. 3, the imaging reference color set 202 includes a plurality of color patches (eg, 301 to 324) arranged in three rows, each consisting of eight color patches.
The color patches 301-324 include the reference color (s) 202a described above with reference to FIGS. 2A, 2B, and 2C.
In the embodiment of the present invention, the color patches 301 to 324 are set against a black background 330 bordered by a white edge 340 and a black edge 350.
In an embodiment of the present invention, the color correction component 204 uses a detection algorithm to identify a pattern that matches the pattern generated by bordering the black background 330 with the white border 340.
The black edge 350 is used to facilitate identifying the white edge 340.
Embodiments of the present invention are not limited to this type of pattern, and any detectable condition provided that the color correction component 204 can detect the pattern when the pattern is present in the image 206. Note that a reference pattern arrangement can be used.
For example, the imaging reference color set 202 may include a background in which colors represented by checkboard patterns, stripes, or color patches 301-324 are incorporated into wallpaper, wall hangings, rugs, and the like.
In another embodiment, the imaging reference color set 202 can include continuous color variations over a desired color range, such as a spectrum of colors or rainbow colors.
Sampling a color from a continuous range may include sampling the entire color range or sampling discrete regions of the continuous range.
In addition, although FIG. 3 shows a rectangular array, the color patches 301-324 can be similarly arranged in circular patterns, triangular patterns, square patterns, and the like.

In the embodiment of FIG. 3, the color patches 301 to 308 include a primary color and secondary color for tone balance of a general scene, and gray + black and white gradation for white balance.
The color patches 309 to 324 include 16 color patches representing the selected color range.
For example, in one embodiment, the color patches 309-324 include a range of human skin colors.
In an embodiment of the present invention, the color description of the control reference color set 203 is known to the color correction component 204 and describes a reference color space or “true” color space independent of lighting and image capture device characteristics. Used to. The imaging reference color set 202 is compared to this reference color space or “true” color space.
For example, in one embodiment, the spectral reflection of each color patch (eg, 301-324) is measured and then approximated as a digital value encoded into a three component standard red, green, blue (sRGB).
These encoded signal values are then compared with the corresponding three-component signal values of the control colors (eg 203a) of the control reference color set 203.

As shown in FIG. 3, the imaging reference color set 202 includes unique identification information 202b.
In an embodiment of the present invention, the unique identification information 202b may include any symbol, character, word, pattern, number, barcode, radio frequency identification (RFID) tag, etc. that the image capture device 201 can recognize. .

By uniquely identifying the reference color set, embodiments of the present invention facilitate identifying the control reference color set 203 whose color characteristics match the color patches 301-324.
This is advantageous when remotely accessing control reference color data that matches the imaging reference color set 202 (eg, by the image capture device 201).
Thus, if the image capture device 201 or display device 220 includes a color correction component 204, a control reference color set 203 that matches the imaging reference color set 202 can be identified using the corresponding identification information 203b and downloaded. Can be done.
Similarly, a carrier or service provider can quickly identify color characteristics that match a particular imaging reference color set 202.

FIG. 4 is a block diagram of a color correction system 400 for providing true color correction according to an embodiment of the present invention.
In an embodiment of the present invention, the color correction component 204 comprises a first access mechanism 401 for accessing the imaging reference color set and a second access mechanism 402 for accessing the control reference color set 203.
In embodiments of the present invention, it is understood that a single access mechanism may be operable to access both the color correction component 204 and the control reference color set 203.
In the embodiment of FIG. 4, the color correction system 400 further includes a function generation component 403 for generating a color correction function (eg, 210) coupled with the first access mechanism 401 and the second access mechanism 402. Prepare.
In an embodiment of the present invention, the first access mechanism 401, the second access mechanism 402, the input 404, the output 405, and the function generation component 403 are described above with reference to FIGS. 2A, 2B, and 2C. The function of the corrected color correction component 204 can be executed.
In the embodiment of FIG. 4, the system 400 further comprises an applicator 205 for applying the color correction function 210 to the image and a data storage device 208 for storing data.
Note that in embodiments of the present invention, the applicator 205 can output a modified color value of the pixels of the image 206 rather than the modified image as described above.
In the embodiment of FIG. 4, the system 400 includes a color adjustment generator 406 for generating adjustments to at least one color control of the display device, and the color adjustment generator 406 and display device (eg, of FIGS. 2B and 2C). 220) and a display output 407 coupled thereto.

In an embodiment of the present invention, the color correction determiner 204 performs automatic detection of the target pattern (eg, the imaging reference color set 202).
In an exemplary object detection sequence, a monochrome (eg, luminance only) version of a color image is filtered using, for example, a Laplacian filter. Thereby, the locus of the maximum brightness change in the image (for example, between the color patches 301 to 324 and the background 330 or between the white edge 340 and the black edge 350) is obtained.
Next, the trajectories of the zero-crossing positions observed in the Laplacian output are connected to a set of closed contours where possible.
Each of these closed contours is then approximated by a series of linear segments. This series of linear segments can be determined through a continuous binary operation based on the deviation of the contour from the straight line.
As a result of the piecewise linear segmentation of the contour (as described above), four main pieces are obtained, the relationship of which coincides with the projection of the plane rectangle (i.e. coincides with the opposite sides being parallel, For those contours, "rectangular candidates" are accepted.
In one embodiment, an outline “candidate rectangle” whose contrast represents a dark exterior (eg, black edge 350) and a bright interior (eg, white edge 340) is located.
Next, a contour “rectangular candidate” whose contrast shows a bright exterior (eg, white edge 340) and a dark interior (eg, black background 330) is located inside the contour.

In an embodiment of the present invention, a set of “rectangular candidate” contours (e.g., color patches 301-324) whose contrast then indicates that the bright interior is set inside the dark exterior is then represented by the contour (e.g. , The edge of the black background 330) is determined.
For example, each of the color patches 301 to 324 is brighter than the black background 330 on which the color patches are arranged.
Two outer “candidate” rectangles (eg, black edge 350 and white edge 340) are used to determine the correct aspect and relationship truth based on the known values of these outlines from the reference target description. A transformation that maps to a rectangle is required.
In this embodiment, the inner contours (for example, color patches 301-324) also have the correct aspect ratio when converted by the above conversion (based on known values of the contours of those color patches). And it is judged whether it exists in the matched location.
Note that some of the color patches may have contrast values that suppress their detection in a given image 202.
However, in embodiments of the present invention, if a sufficient number of internal color patches are detected (eg, a suitable measure of “sufficiency” may be 90%), the reference object is that detected. It is recognized.
In an embodiment of the present invention, the color values inside the detected and validated color patch are sampled and used as sample values to establish a true color transformation performed by the color correction component 204. .
Since the orientation of the imaging reference color set 202 may be ambiguous in some situations, when strictly using the geometric rectangle scale, by assessing the placement of the color patches 301-324 themselves, The orientation of the imaging reference color set 202 can be determined.
In other embodiments, featured markings (eg, a geometric pattern, or a geometric pattern of color patches 301-324) reveal the orientation of the imaging reference color set 202 through its shape or relationship. can do.

In an embodiment of the present invention, the color correction component 204 can also check the validity of the imaging reference color set 202 upon detection to ensure the fidelity of the color patches 301-324 of the imaging reference color set 202. .
For example, if the color patches 301-324 fade or change color due to a stain, the result of sampling the color patch by the color correction component 204 may be distorted.
As a result, the estimation of the color correction function 210 by the color correction component 204 may give incorrect results.
Thus, in an embodiment of the present invention, the color correction component 204 can check the validity of the age or version of the imaging reference color set 202.
In another embodiment, the unique identification information 202b can be used to determine when the imaging reference color set 202 has been created, and therefore whether the imaging reference color set 202 is still valid. Can also be judged.
Alternatively, one or more of the inks used to create the imaging reference color set 202 can be selected to fade after a given time.
As a result, portions of the imaging reference color set 202 may not be able to recognize the color correction component 204, thereby preventing further estimation of the color correction function from the imaging reference color set 202.
In another embodiment, a message may be displayed informing the user that the one or more fades of ink have expired the imaging reference color set 202 and that a new version is required.

In an embodiment of the present invention, if it is determined that the imaging reference color set 202 is a valid copy, the color correction component 204 then proceeds to the color space of the imaging reference color set 202 and the control reference color set 203. The color correction function 210 is obtained by estimating the color conversion, also called “conversion function”.
In one embodiment of the invention, least squares estimation is used to control the measured patch average color M from the imaging reference color set 204 (eg, from one or more of the color patches 301-324). A color correction function F in the form of a 3 × 4 matrix that maps to the corresponding control color value R of the color set 203 is derived.
In other embodiments, the measured patch average color value can be processed through an inverse gamma function to remove the effects of device nonlinear contrast adjustment.
This matrix is a conversion function F obtained by adding an offset per additional color component to the 3 × 3 color conversion matrix.
In an embodiment of the present invention, the patch average color having at least one saturation component is excluded and the sRGB color component function is inverted for both M and R before performing the least squares estimation.
In other embodiments, the measured patch average color value can be processed through an inverse gamma function to remove the effects of device nonlinear contrast adjustment.
However, although a 3 × 4 matrix can be used to determine the color correction function, embodiments of the present invention are not limited to linear algebra to determine this function.
In other words, the color correction function 210 can take an arbitrary function form.

In an embodiment of the invention, all of the color patches from the imaging reference color set 202 can be measured and used to determine the color correction function 210.
In another embodiment, color patches can be selectively sampled.
For example, in one embodiment, only color patches (eg, 301-308) of primary, secondary, and monochrome colors (eg, blue, green, red, cyan, magenta, yellow, and gray tones) Used to determine the correction function 210.
Embodiments of the present invention can also sample white tones from the white edge 340 and sample black tones from the background 330 or the black edge 350.
In another embodiment, all of the color patches (eg, color patches 309-324) as well as black tone, white tone, and gray tone are sampled to determine the color correction function 210.
In another embodiment, only color patches (eg, color patches 309-324) are sampled to determine the color correction function 210.
In embodiments of the present invention, it may be advantageous to provide an imaging reference color set 202 in which the color patches 309-324 are closely aligned with the color scheme of the subject 211.
For example, if subject 211 is a red car, it may be advantageous to select imaging reference color set 202 where color patches 309-324 are primarily red tones.
In such an embodiment, it may be advantageous to sample only the color patches 309-324 in order to determine the color correction function that is best suited for estimating the color of the subject 211.
For example, sampling all of the imaging color patches from the imaging reference color set 202 may result in the color correction function 210 being best suited to correct the overall image color. However, it may not always be best suited to correct the imaged color of the subject 211.
Therefore, when estimating a color correction function suitable for use in estimating the color of the subject 211, high-density sampling of the target color region (eg, car red tone) can be performed over a wide overall color space. It may be more important than sampling.

Accordingly, the color correction component 204 determines a color correction function 210 that substantially eliminates the difference between the imaging reference color set 202 and the control reference color set 203.
If the color correction function 210 is denoted as F in any functional form, this is the formula:
I_R = F (I_C)
Can be represented by Here, I_R is a color in the control reference color set 203, and I_C is a corresponding color from the imaging reference color set 202.
When applied to the image 206, the color correction function 210 attempts to accurately convey the color of the image 206 by compensating for ambient lighting conditions and the effects of the image capture device 201.
Note that color correction 210 may only be an approximation.
For example, the color correction function F may not map each image color acquired from the imaging reference color set 202 to its exact corresponding reference color in the control reference color set 203.
Further, F may lack the accuracy necessary to cause an exact match with the reference color in the control reference color set 203 when applied to the corresponding color in the imaging reference color set 202. Understood.
For the purposes of the present invention, the phrase “substantially remove” means that the color of subject 211 after F is applied to the color value 412 of the identified skin pixel of image 206 (or the color description of image 206, for example). And the corrected color of the subject 211 represented by the modified image 207 cannot be easily identified, i.e., within an acceptable range.

FIG. 5 is a block diagram of an exemplary computer system 500 upon which an embodiment of the invention may be implemented.
In embodiments of the present invention, portions of the present invention are comprised of computer-readable and computer-executable instructions that reside, for example, in computer system 500 used as part of a general purpose computer network (not shown). The
The computer system 500 of FIG. 5 is exemplary only and the invention includes general purpose computer systems, embedded computer systems, laptop computer systems, handheld computer systems, networked computer systems, and stand-alone computer systems. It will be understood that it can operate within a plurality of different computer systems.

In this embodiment, computer system 500 includes an address / data bus 501 for carrying digital information between various components, a central processing unit (CPU) 502 for processing digital information and instructions, and digital information and instructions. A volatile main memory 503 composed of a volatile random access memory (RAM) for storing, and a nonvolatile read-only memory (ROM) 504 for storing information and instructions of a more permanent nature are provided.
In addition, the computer system 500 can also include a data storage device 505 (eg, a magnetic drive, an optical drive, a floppy drive, or a tape drive) for storing a huge amount of data.
It should be noted that the software program for performing skin color estimation of the present invention may be stored in either the volatile memory 503, the data storage device 505, or an external storage device (not shown).

Optional devices coupled to computer system 500 include a display device 506 for displaying information to a computer user, an alphanumeric input device 507 (eg, a keyboard), and a cursor for entering data, selections, updates, etc. A control device 508 (eg, mouse, trackball, light pen, etc.) is included.
Computer system 500 can also include a mechanism (not shown) for emitting audible signals.

With further reference to FIG. 5, the optional display device 506 of FIG. 5 may be a liquid crystal device, a cathode ray tube, or other display device suitable for creating user-recognizable graphic images and alphanumeric characters. Can do.
An optional cursor controller 508 allows the computer user to dynamically signal the two-dimensional movement of the visible symbol (cursor) on the display screen of the display device 506.
Many implementations of the cursor controller 508 include a trackball, mouse, touchpad, joystick, or special keys on the alphanumeric input 507 that can signal displacement movement in a given direction or style. Known in the art.
Alternatively, it will be appreciated that the cursor may be directed and activated via input from alphanumeric input 507 using special keys and key sequence commands.
Alternatively, the cursor can be directed and activated via input from a plurality of specially adapted cursor directing devices.

Further, the computer system 500 can also include an input / output (I / O) signal unit (eg, interface) 509 for interfacing with peripheral devices 510 (eg, computer networks, modems, mass storage devices, etc.). .
Accordingly, the computer system 500 can be coupled within a network, such as a client / server environment, whereby multiple clients (eg, personal computers, workstations, portable computers, minicomputers, terminals, etc.) can perform the desired task. Used to execute a process to execute.
In particular, the computer system 500 can be coupled in a system for estimating skin color from a single captured image.

200 Image Capture System 201 Image Capture Device 202 Imaging Reference Color Set 202a Reference Color 202b Unique Identification Information 203 Control Reference Color Set 203a Control Color 203b Corresponding Identification Information 204 Color Correction Component 205 Applicator 206 Image 207 Modified Image 208 Data Storage Device 209 Network 210 Color correction function 211 Subject 220 Display device 221 Display 222 Physical control reference color set 222a Physical reference color 222b Unique identification information 223 Adjustment 401 First access mechanism 402 First access mechanism 403 Function generation component 404 Input 405 Output 406 Color adjustment generator 407 Display output 500 Computer system 502 Processor 503 Volatile memory (RAM)
504 Nonvolatile memory (ROM)
505 Data storage device 506 Display device 507 Alphanumeric input 508 Cursor control 509 Input / output communication device 510 Peripheral device

Claims (10)

An image capture system for transmitting the true color of a subject,
An image capture device (201);
An imaging reference color set (202) including at least one reference color (202a);
A control reference color set (203) including at least one control color (203a) corresponding to the at least one reference color (202a);
Color correction that accesses the control reference color set (203) and the imaging reference color set (202) to remove differences between the at least one reference color (202a) and the at least one control color (203a) An image capture system comprising: a color correction component (204) for generating a function (210). Applicator (205) for creating a modified image (207) by applying the color correction function (210) to the image (206)
The image capture system according to claim 1, further comprising: The applicator (205) comprises components of the image capture device (201),
The image capture system of claim 2, wherein the color correction component (204) is communicatively coupled to the image capture device (201). The image capture system of claim 2, wherein the applicator (205) and the color correction component (204) comprise components of the image capture device (201). The imaging reference color set (202) further includes unique identification information (202b),
The image capture system of claim 1, wherein the control reference color set (203) matches the imaging reference color set (202) uniquely identified by the unique identification information (202b). Data storage device (208) for storing the color correction function (210)
The image capture system according to claim 1, further comprising: A display device (220) for generating a display (221) selected from the group consisting essentially of a projected display, a printed display, and a digitally generated display.
The image capture system according to claim 1, further comprising: The image capture system of claim 7, wherein the color correction component (204) generates an adjustment (223) for at least one color control of the display device (220). The image capture device (201) captures an image (206) of a physical control reference color set (222) disposed proximate to the display (221);
The image capture system of claim 8, wherein the display (221) includes the imaging reference color set (202). The image capture system of claim 8, wherein the display (221) conveys a modified image (207) to which the color correction function (210) has been applied.

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