WO2014131920A1

WO2014131920A1 - Method and device for measuring and calculating colorimetric parameters of illuminated objects and light sources

Info

Publication number: WO2014131920A1
Application number: PCT/ES2013/070128
Authority: WO
Inventors: José Antonio GUTIÉRREZ MÉNDEZ; Alberto Mansilla Gallo; Jesús Ángel REAL CORTÉS
Original assignee: Fundación Cidaut
Priority date: 2013-03-01
Filing date: 2013-03-01
Publication date: 2014-09-04

Abstract

The invention relates to a method and a device for measuring and calculating colorimetric parameters of any illuminated object and light source. The method is dynamic and measures the ambient lighting, a total or partial area of the illuminated object or light source, and calculates the colorimetric parameters in said total or partial area for any type of desired lighting, eliminating the contribution of the ambient lighting. The device is a mobile system including at least one light sensor with a spectral response at different wavelengths of the visible electromagnetic spectrum.

Description

PROCEDURE AND DEVICE FOR MEASUREMENT AND CALCULATION OF COLORIMETRIC PARAMETERS OF ILLUMINATED OBJECTS AND

LUMINOUS SOURCES TECHNICAL FIELD OF THE INVENTION

The present invention relates to a

procedure and device for measuring and calculating colorimetric parameters of any illuminated object and light source.

The procedure is dynamic and measures the

ambient lighting, a total or partial area of the illuminated object or light source and calculates the

colorimetric parameters in said total or partial zone for any type of desired lighting, eliminating the contribution of ambient lighting.

The device is a mobile system that includes at least one light sensor with spectral response at different wavelengths of the spectrum

visible electromagnetic, and, optionally, as help has a global positioning system, one of inertial navigation and computer systems.

BACKGROUND OF THE INVENTION

Illuminated objects and light sources, of any kind, can be found on the road in the form of panels, signs, "cat eyes", road markings, on walls and asphalt in tunnels, etc.

We understand as illuminated objects, both the objects that can be illuminated with a focus

specific on its outside (called objects) externally illuminated), as those illuminated from within (denominated internally illuminated), as those not illuminated or externally, in reference to the specific focus, or internally. When the objects are not illuminated, they can have the surface with

retroreflective features (to increase its visibility).

Regarding the light sources, it is understood as such the road lighting, the luminous panels of variable message (PMV) or fixed (such as traffic lights or others), or other light signals that can be found on the road (such as vertical signs) of circulation -or others- where on its surface they have point lights -led or similar- or continuous -light strips-).

Both in the light sources and in the illuminated objects, of any type, it is necessary to carry out periodic maintenance tasks for

ensure a minimum level of photometric performance over time, especially in the requirements of luminance, luminous intensity, coefficient of

retroreflection, color parameters, etc.

For this, it is necessary to measure a set of these color parameters, also called

colorimetric or chromatic, that allow the evaluation of the illuminated object or light source, with a view to identifying the appropriate moment of the replacement of its components or its complete replacement, and therefore, optimizing the costs of revision or maintenance and replacement costs. The magnitudes on which the indicators of the good functioning of illuminated objects and light sources are usually

standardized or subject to certain criteria of minimum behavioral benefits. In most of the products there are regulations that evaluate the photometric parameters, especially the color, limiting for example the valid chromatic coordinates

recommended for each color. These measurements are made in controlled scenarios, typically a laboratory.

However, for the evaluation of these parameters in service, it is necessary to measure them in situ, where the measurement conditions are not the same as in a laboratory, and they can be very variable and not

controllable

A light source is characterized by an electromagnetic spectrum. From it, multiple parameters are calculated, such as the color temperature, which is the temperature at which a black body would have a color similar to the sample. The sun resembles a black body with a temperature of 5700K in its

surface. The electromagnetic spectrum depends on many aspects, mainly the temperature of the emitting source (filaments in the case of a light bulb) and the nature of the materials (gases, halides, etc.).

From the earth the solar radiation depends on the filter of the atmosphere, so the radiation varies depending on the cloudiness, it is as if the temperature of the surface of the sun changed.

When the sky begins to cloud, the spectrum changes, resembling a black body with a higher temperature, reaching even the 7500K of color temperature correlated. The more cloudy the day, the blueter the objects. The more clear, the more red they appear.

Under this range of illumination, the measurement of color is complicated since, depending on the spectral emission of the sun, the measurement of the color can vary. The colorimetry is calculated, according to the regulations, for an illumination of a black body at 2856 K, precisely the emission of a classic tungsten filament lamp. Other color measurement systems, for example for vertical traffic signals, are based on illuminants D65, temperature of a black body at 6500K.

On the other hand, the color depends a lot on the illuminant. A white object can be seen the color you want, illuminating it with a font

luminous of the desired color. In addition, the chromatic coordinates with different illuminants, may not be additive so they must be converted to a single lighting system. The chromatic coordinates do not depend on the amount of light they emit, but in our case, when they are illuminated, we must know how much the external source contributes to the color (amount of light). This amount of light should be measured with a luxometer. The international lighting committee, CIE, aware of this problem, has developed various mathematical tools to translate the chromatic coordinates of one illuminant to another. These tools are usually linear systems (matrices). However, the controlled scenario of a laboratory does not allow the assessment of the state of the illuminated objects and light sources to be made based on magnitudes measured in service conditions, that is, in dynamic conditions and in environments where external lighting is not controllable.

Therefore, there is the disadvantage of the impossibility of disassembling the illuminated object or the light source to perform the measurements in the

laboratory or the design of an experiment in nocturnal environments with artificial lighting.

In the patent with publication number EP1486799 the road markings are identified by the difference in luminance in an image, which is brighter than the surrounding asphalt. When the center of the mark is measured, its color is measured, identified if it is yellow or white, depending on the ratio of blue or red. Thus, colorimetric parameters are calculated as dominant color and said parameters are compared empirically with limit values. This comparison determines the color. In the patent with publication number

US6674878 color images are used in a system to determine the retroreflectivity of reflective surfaces arranged along a pathway for

automobiles To do this, an area of said road is illuminated with different intensity values, a processing system identifies a section of the values of

intensity associated with the reflective surface and analyzes that section to determine the

retroreflectivity of the surface. Multiple color images are captured with a color camera, preferably two cameras for generating stereoscopic images. The range of colors of the

characterization of the light source and the color images are used to determine the

retroreflectivity. For each object, the intensity of the object is measured in the foreground, and that of the background, using an intensity algorithm, the luminances are determined. With these, the characterization of the light source and the color chart of the object and the background, the retroreflectivity of the object and the background is obtained.

In the patent with publication number US7995796 a system classifies different types of laminated materials for road signs, by means of a video. Once the signal has been identified in the video, different portions associated with the signal are added to determine each of the colors

present in the signal, with what is estimated

refetrorreflectivity. Comparing this with minimum values, a classification of the laminated materials is obtained. For the same purpose, the

retroreflectivity of foreground and background colors of a signal. In order to overcome the aforementioned disadvantages, a dynamic method for measuring colorimetric parameters of any illuminated object and light source and the device used to carry out said procedure is proposed in the present application.

process.

DESCRIPTION OF THE INVENTION

In view of the aforementioned, the present invention relates to a method of measurement and calculation of colorimetric parameters

any illuminated object and light source and a device for carrying out said procedure. The invention has the objective of measuring and calculating performance indicators,

especially photometric, in dynamic mode in a natural light environment controlled or not, without altering traffic, in order to establish verification, calibration and maintenance tasks, among others. That is, the objective of the invention is to know the colorimetric parameters of an illuminated object or light source under another illuminant different from the ambient, and to do it in a dynamic way.

Said procedure is for measuring and calculating colorimetric parameters, such as chromatic coordinates in different color spaces, color temperature, Color Rendering Index or CRI, etc.

Said procedure is carried out on any illuminated object and light source.

Likewise, it is carried out in the presence of ambient lighting of any type, natural, such as the sun, or artificial, which may be, in some cases, negligible the value of said ambient lighting.

It is then possible to measure and transfer the measurements made on the illuminated object or light source in an environment, to another environment with a desired level of illumination, while advancing towards the object or luminous source.

The procedure is characterized in that it is dynamic and comprises the following stages:

a) measurement of a collection of external illumination data E _r , relating to the spectrum of illumination F _r () and colorimetric parameters in any type of color measurement system, such as the C IE (Xer _í Yer) _Í from a mobile system approaching or moving away from the object or light source and through a system for measuring external lighting; b) measurement of a set of colorimetric parameters in a total or partial area of the illuminated object or light source (these parameters can be the spectrum F ₀ - _f {X), the chromatic coordinates in any type of color measurement system, such as for example the C IE (x ₀ -f, and ₀ - _f ), the color temperature, the color rendering index CRI, etc.) by means of at least one light sensor (5) with response to different wavelengths of the spectrum

electromagnetic visible, directed towards the field of vision of the mobile system;

c) calculation of the colorimetric parameters in said total or partial area of the illuminated object or light source, for any type of desired illumination E _n and with an illuminant with spectrum F _n {X), by eliminating the contribution of the initial ambient illuminant E _r and with illumination spectrum F _r (X).

The device for the measurement and calculation of colorimetric parameters of any illuminated object and light source, according to the exposed method, includes a mobile system characterized in that it comprises a system for measuring the external illumination and a light sensor with response to different lengths of light. wave of the visible electromagnetic spectrum, directed towards the field of vision of the mobile system, and, optionally, as a help has a global positioning system, one of inertial navigation and computer systems.

An advantage of the invention is that it allows to measure and calculate the necessary parameters for the review or evaluation of the illuminated objects and the light sources in a direct way, directly measuring the physical parameter. As well as that it can be done automatically, without intervention by the user once set up, or it is also possible manually, intervening the user in the different stages, for all the illuminated objects and light sources that appear in a scene and in service.

Another advantage is that it is applicable

regardless of the type of illuminated object or light source, and of the technology used as a visualizing element. As well as independently of the ambient light emitted, that is to say under diurnal or nocturnal conditions and in interior or exterior spaces.

BRIEF DESCRIPTION OF THE FIGURES The present descriptive memory is complemented with a set of figures, illustrative of the preferred example, and never limiting of the invention.

Figure 1 represents a view of a vehicle as a mobile system, equipped to carry out the described procedure on an illuminated object or light source, circulating and approaching it.

CARVING EXHIBITION OF THE PREFERRED EMBODIMENT OF THE

INVENTION The present invention relates to a method and a device for measuring and calculating colorimetric parameters of any illuminated object and light source (1).

The objects and light sources (1) can be arranged along a track (2), which can be of any type, such as a street, road or tunnel, or even rail. They can also be of any type, such as variable message light panels, internal or externally illuminated signs, road lighting of any kind, such as streets, roads and tunnels, traffic lights, vertical signs and beacons, etc.

It is assumed that there is an illuminated object or a light source (1) inside the environment with a controllable light or not, for example, the sun, whose spectrum or color temperature can vary at any time, mainly due, among other factors , because the interaction with the atmosphere causes its color temperature to change. The object of the invention is to know the colorimetric parameters of said illuminated object or light source (1) under a different illuminant, for example a normalized standard illuminant, and to do it in a dynamic way.

To do this, we must first eliminate the "contribution" to the colorimetric parameters of the illuminant present in the environment, for example the sun Asi, we must measure the colorimetric parameters (for example the chromatic coordinates), in any type of measurement system of color, such as the CIE (x, y), of the elements that make up the object illuminated or the light source (1) under ambient lighting conditions, as the chromatic coordinates can not be added directly, they must all be measured with the same illuminant.

For example, a white material with color coordinates x = 0.333, y = 0.321 measured with a Xenon beacon, will have others, for example: x = 0.422, y = 0.345, measured with a halogen headlight. For its part, a blue material illuminated with a red laser, will not have blue color but will look black, but if it is illuminated with "white" light it will look blue.

Thus, in the first stage of the procedure, a collection of ambient lighting data E _r , relative to the illumination spectrum F _r () and

colorimetric parameters in any type of color measurement system, from a mobile system (3)

approaching or moving away from the object or light source (1) and through a system for measuring external lighting (7). Subsequently, in a second stage, a set of colorimetric parameters is measured in a total or partial area of the illuminated object or light source (1.1) by means of at least one light sensor (5) with response to different wavelengths of the visible electromagnetic spectrum , directed towards the field of vision of the mobile system (3).

Once the colorimetric parameters (for example the chromatic coordinates) are known, in any type of color measurement system, such as the CIE (x, y), under ambient lighting, it is necessary to

transfer them to the desired illuminant, that is, the

standardized or prefixed illuminant. By way of example, to mention that the way of knowing said chromatic coordinates is carried out by means of calculation with the mathematical expression Μ _εη (λ) for the translation, and it is usually a 3x3 matrix, an expression known in the art field although particular for each case. For example, according to the norm ASTM E308-01 to pass from an illuminant A to an illuminant C the matrix is the following, being nii _j the elements of the same one:

m ₂ i = 0, m ₂₂ = l, m ₂₃ = 0,

m ₃₂ = 0, m ₃₃ = 3.3225235. From the triestimulos Χ, Υ, Ζ obtained, thanks to said matrix of change between different spaces, the coordinates are calculated

chromatic by the expressions: x = X / (X + Y + Z), y = Y / (X + Y + Z).

At the end the parameters are obtained

colorimetric of the elements of the object or of the light source, for a level of luminous intensity of the standardized or prefixed illuminant, that is to say, in a third stage the colorimetric parameters are calculated in the total or partial area of the illuminated object or light source (1.1 ), for any type of desired illumination E _n and with an illuminant with spectrum F _n {X),

by eliminating the contribution of

illuminant initial environment E _r and with spectrum

lighting F _r ().

It is possible that the ambient lighting, E _r , is negligible, the stages being equally valid

exposed.

The procedure is dynamic because it is applied in motion, for example on the road itself when it is a vehicle, and without altering the traffic, that is, it is not necessary to close the road during the application of the vehicle. dynamic procedure.

Optionally, the parameters

Colorimetric images are acquired through images, which are obtained through multiple light sensors

(5) that configure a photosensitive plate, said parameters being calculated in the area of the image containing the illuminated object or light source. In this way, color cameras (or black and white with color filters) appropriate for this purpose can be used, thus being known instruments, cameras, and relatively easy to acquire in the market.

Preferably, the device used to measure external lighting from the mobile system (3) is a luxometer (7), although it could be any other. The measured value of E _r will be assumed to be similar to that of the ob ete or light source (1). Said measurement can be performed at distances or at known time intervals, which, although not necessary, is beneficial to obtain the measured values with greater accuracy. In turn, from the mobile system itself (3), data can be acquired from other sensors (6), such as: GPS, odometer, temperature, humidity or others. The position data will preferably be acquired by a global positioning system (8) and inertial navigation (9).

These data may be acquired at distances or at known time intervals, synchronized or not, with a sufficiently high frequency or data rate. Optionally, the control of switching off and on of the elements of the light source or illuminated object (1) can be done manually or taking advantage of the flickering of said sources. For example, a European 50 Hz lamp is turned off and on 100 times per second. A regulation of LED panels, although it could be any other, indicates that the frequency of switching off and on must be greater than 90 Hz. Therefore, it would suffice to use a data collection higher than this frequency or data collection techniques conveniently separated from one another in such a way as to be sufficient for the purpose.

Thus, this procedure is also valid for any ignition frequency (excessively high and even zero) that the light sources may have, and the existing lighting of the environment and the lighting system used for the illuminated objects. With the calculated values it will be possible to review or evaluate the indicators of good functioning of the illuminated objects and light sources (1) in a direct way, that is, by dynamically measuring the physical parameter in the environment of uncontrolled natural light, without having to travel to a laboratory. As well as, perform it automatically, without the intervention of a user, for all the illuminated objects and light sources (1) that appear in a scene and / or in

service

The illuminated objects and light sources (1) can be arranged, like the mobile system (3), along any linear infrastructure of

land transport (2): rail, road or road of any kind. The device for the measurement and calculation of colorimetric parameters of any illuminated object and light source (1), as set forth above, includes a mobile system (3) that at least comprises an external lighting measurement system (7) and a light sensor (5) with response to different

wavelengths of the visible electromagnetic spectrum, directed towards the field of vision of the mobile system (3).

Optionally, one or more of the following elements can be included in said mobile system (3): a global positioning system (8), an inertial navigation system (9), computer systems (10).

As a measuring system for external lighting (7) the most usual option is to be a luxometer.

Also, in addition to the light sensor (5) another sensor (6) can be included, such as an odometer, a temperature sensor and / or a humidity sensor.

In particular, the light sensor (5) can be a digital color camera or black and white camera with suitable filters.

Claims

1. Measurement procedure and calculation of colorimetric parameters of any illuminated object and light source (1) characterized by being dynamic and comprising the following stages:

a) measure of a collection of lighting data

environment E _r , relative to the spectrum of illumination F _r () and colorimetric parameters in any type of color measurement system, from a mobile system (3) approaching or moving away from the object or light source (1) and through a system of measurement of external lighting (7);

b) measurement of a set of colorimetric parameters in a total or partial area of the illuminated object or light source (1.1) by means of at least one light sensor (5) with response to different wavelengths of the visible electromagnetic spectrum,

directed towards the field of vision of the mobile system (3);

c) calculation of the colorimetric parameters in said total or partial area of the illuminated object or light source (1.1), for any type of desired illumination E _n and with an illuminant with spectrum F _n {X), by eliminating the contribution of the illuminant initial environment E _r and with illumination spectrum F _r ().

2. Method for measuring and calculating colorimetric parameters of any illuminated object and light source according to claim 1, wherein in step b) the colorimetric parameters are acquired through images, which are obtained by means of multiple light sensors ( 5) that make up a plate

photosensitive, calculating said parameters in the stage c) in the area of the image containing the illuminated object or light source (1).

3. Measurement procedure and calculation of colorimetric parameters of any illuminated object and light source according to claim 1 wherein values of sensors (6) are taken as GPS, odometer, temperature and / or humidity at the same time of measurement of stage a).

4. Method for measuring and calculating colorimetric parameters of any illuminated object and light source according to claim 1, wherein the

Ambient lighting, E _r , is negligible.

5. Method for measuring and calculating colorimetric parameters of any illuminated object and light source according to claim 1, wherein the external lighting measurement system (7) is a

luxmeter.

6. Method of measurement and calculation of colorimetric parameters of any illuminated object and light source according to claim 1 wherein the

procedure is automatic.

7. Method of measurement and calculation of colorimetric parameters of any illuminated object and light source according to any of the preceding claims, wherein the frequency of power on and off of the source is excessively high or zero.

8. Measurement procedure and calculation of colorimetric parameters of any illuminated object and light source according to any of the claims previous in which the illuminated object or the light source (1) is arranged along any linear infrastructure of land transport (2).

9. - Device for the measurement and calculation of colorimetric parameters of any illuminated object and light source, according to any of the previous claims, which includes a mobile system (3)

characterized in that it comprises a system for measuring the external illumination (7) and a light sensor (5) with response to different wavelengths of the visible electromagnetic spectrum, directed towards the field of vision of the mobile system (3).

10. Device for the measurement and calculation of colorimetric parameters of any illuminated object and light source according to claim 8, which also comprises a global positioning system (8).

11. Device for the measurement and calculation of colorimetric parameters of any illuminated object and light source according to claim 8, further comprising an inertial navigation system (9).

12. - Device for the measurement and calculation of colorimetric parameters of any illuminated object and light source according to claim 8 further comprising computer systems (10).

13. Device for the measurement and calculation of the colorimetric parameters of any illuminated object and light source according to claim 8, in which the external lighting measurement system (7) is a luxometer.

14. Device for the measurement and calculation of colorimetric parameters of any illuminated object and light source according to claim 8, further comprising at least one sensor (6), such as an odometer, a temperature sensor and / or a humidity sensor.

15. Device for the measurement and calculation of the colorimetric parameters of any illuminated object and light source according to claim 8, wherein the light sensor (5) is a digital color camera or black and white camera with suitable filters.