WO2021079008A1

WO2021079008A1 - Method for managing image data and automotive lighting device

Info

Publication number: WO2021079008A1
Application number: PCT/EP2020/080086
Authority: WO
Inventors: Yasser ALMEHIO
Original assignee: Valeo Vision
Priority date: 2019-10-25
Filing date: 2020-10-26
Publication date: 2021-04-29
Also published as: FR3102630A1

Abstract

The invention provides a method for managing image data in an automotive lighting device (10). This method comprises the steps of providing an image pattern (1) and defining a variation pattern (2), wherein a pixel (21) of the variation pattern (2, 3) is related to the difference of luminous intensity between two pixels (11) of the image pattern (1). Afterwards, this variation pattern (2, 3) is compressed, thus creating a compressed variation pattern, which is sent to a light module (4). The invention also provides an automotive lighting device (10) for performing the steps of such a method.

Description

Title: Method for managing image data and automotive lighting device

[0001] [This invention is related to the field of automotive lighting devices, and more particularly, to the management of the electronic data derived from the control of the lighting sources.

[0002] Current lighting devices comprises an increasing number of light sources which has to be controlled, to provide adaptive lighting functionalities.

[0003] This number of light sources involves a big amount of data, which has to be managed by the control unit. The CAN protocol is often used, in some of their variants (CAN-FD is one of the most used ones) to transfer data between the PCM and the light module. However, some car manufacturers decide to limit the bandwidth of the CAN protocol, and this affects the management operations, which usually requires about 5 Mbps.

[0004] Current compression methods are not very efficient for high beam patterns, and this compromises the bandwidth reduction which is requested by car manufacturers.

[0005] A solution for this problem is sought.

[0006] The invention provides a solution for these problems by means of a method for managing image data according to claim 1 and an automotive lighting device according to claim 10. Preferred embodiments of the invention are defined in dependent claims.

[0007] Unless otherwise defined, all terms (including technical and scientific terms) used herein are to be interpreted as is customary in the art. It will be further understood that terms in common usage should also be interpreted as is customary in the relevant art and not in an idealised or overly formal sense unless expressly so defined herein.

[0008] In this text, the term “comprises” and its derivations (such as “comprising”, etc.) should not be understood in an excluding sense, that is, these terms should not be interpreted as excluding the possibility that what is described and defined may include further elements, steps, etc.

[0009] In a first inventive aspect, the invention provides a method for managing image data in an automotive lighting device, the method comprising the steps of

- providing an image pattern with a plurality of light pixels;

- defining a variation pattern with a plurality of light pixels, wherein a pixel of the variation pattern is related to the difference of luminous intensity between two pixels of the image pattern;

- compress the variation pattern, thus creating a compressed variation pattern; and

- send the compressed variation pattern to a light module.

[0010] This method is aimed to manage the image data which is exchanged between a control unit and a light module. The control unit is in charge of calculating the image pattern and the variation pattern, and may be located in any position of the automotive vehicle, not necessarily physically inside the lighting device. The lighting module is aimed to provide a light pattern, either for lighting or signalling, and is located inside the lighting device.

[0011] The main advantage of this method is the increase in the compression rate, due to the fact that the variation pattern comprises a lower amount of data compared to the original image pattern, specially when the image pattern is referred to a high beam pattern. The variation pattern also comprises a high number of repetitive values, which also contributes to the compression rate being increased.

[0012] In some particular embodiments, the light pixels of the image pattern are grey scale pixels, and more particularly, the luminous intensity of each pixel is according to a scale from 0 to 255.

[0013] Light modules usually define the light pattern on a grey scale, where the luminous intensity is graded from 0 to 255. This is a way of quantifying the light pattern so that it becomes able to be converted into light data, and then transmitted and managed by the PCM of the vehicle. [0014] In some particular embodiments, a pixel of the variation pattern is related to the difference of luminous intensity between two adjacent pixels of the image pattern. In some particular embodiments, a pixel of the variation pattern is related to the difference of luminous intensity between a pixel of the image pattern which is in the same position and the adjacent pixel.

[0015] This way, an easy pattern is created, where the luminous value of a pixel of the variation pattern corresponds to the difference in the luminous intensity of the same pixel in the image pattern and an adjacent pixel. To restore the original light pattern, a simple addition operation is needed.

[0016] In some particular embodiments, the variation pattern is related to the image pattern following the formulae

D (i, 1 ) = F (i, 1 ) for j > 1 , D (i, j) = F (i, j) - F (i, j-1 ) wherein D is the variation pattern and F is the image pattern, and the indexes i and j are referred to the row and column inside the pattern.

[0017] The first column is maintained in the original way, to be used as reference values. The rest of the matrix values are calculated by subtracting the values of one column minus the adjacent column. The same operation could be done with rows instead of columns for a similar result.

[0018] In some particular embodiments, the method further comprises the step of normalizing the variation pattern by adding a compensation value to at least some of the pixels of the variation pattern so that the lower value of the normalized variation pattern is equal or greater than zero, and the step of compressing the variation pattern is applied over the normalized variation pattern.

[0019] This normalizing step reduces the number of bits, since a sign bit becomes not necessary.

[0020] In some particular embodiments, before the step of compressing the variation pattern, the number of bits necessary to characterize a pixel is integrated. [0021] In the variation pattern, the range of numbers may be much lower, passing from 0 to 255 to a range which can be 0 to 15. In these cases, the number of bits necessary to characterize one pixel is half the number of bits in a traditional method. As a consequence, the integration of this change in the compression algorithm may improve the compression rate.

[0022] In some particular embodiments, the method further comprises the step of decompressing the compressed variation pattern.

[0023] This step is convenient when the original image is to be projected by the light module.

[0024] In some particular embodiments, the variation pattern is related only to a particular portion of the image pattern.

[0025] This cropping step is useful when a big portion of the image is completely dark, so that the compression stage is focused only on the portion which include representative values.

[0026] In a second inventive aspect, the invention provides a lighting device comprising

- a light module comprising a plurality of light sources; and

- a control unit to carry out the steps of a method according to the first inventive aspect.

[0027] This lighting device is able to operate with a lower bandwidth than the traditional ones.

[0028] In some particular embodiments, the light module further comprises a processor unit, the processor unit being configured to decompress the compressed variation pattern.

[0029] With a decompression stage in the proper light module, the bandwidth is narrowed until the module itself.

[0030] In some particular embodiments, the light sources are solid-state light sources, such as LEDs. The term "solid state" refers to light emitted by solid-state electroluminescence, which uses semiconductors to convert electricity into light. Compared to incandescent lighting, solid state lighting creates visible light with reduced heat generation and less energy dissipation. The typically small mass of a solid-state electronic lighting device provides for greater resistance to shock and vibration compared to brittle glass tubes/bulbs and long, thin filament wires. They also eliminate filament evaporation, potentially increasing the life span of the illumination device. Some examples of these types of lighting comprise semiconductor light-emitting diodes (LEDs), organic light-emitting diodes (OLED), or polymer light-emitting diodes (PLED) as sources of illumination rather than electrical filaments, plasma or gas.

[0031] To complete the description and in order to provide for a better understanding of the invention, a set of drawings is provided. Said drawings form an integral part of the description and illustrate an embodiment of the invention, which should not be interpreted as restricting the scope of the invention, but just as an example of how the invention can be carried out. The drawings comprise the following figures:

[0032] [Fig 1] shows a first image of the photometry of a high beam module which is projected by an automotive lighting device according to the invention.

[0033] [Fig 2] shows a portion of a pixel matrix representing the photometry of [Fig 1].

[0034] [Fig 3a] and [Fig 3b] show a portion of a variation matrix and a normalized variation matrix obtained as intermediate steps by a method according to the invention.

[0035] [Fig 4] shows an automotive lighting device according to the invention.

[0036] Elements of the example embodiments are consistently denoted by the same reference numerals throughout the drawings and detailed description where appropriate:

[0037] 1 Image pattern

[0038] 11 Pixel of the image pattern

[0039] 2 Variation matrix

[0040] 21 Pixel of the variation matrix

[0041] 3 Normalized variation matrix [0042] 4 Light module

[0043] 5 LEDs

[0044] 6 Control unit

[0045] 7 Processor unit

[0046] 10 Automotive lighting device

[0047] 100 Automotive vehicle

[0048] The example embodiments are described in sufficient detail to enable those of ordinary skill in the art to embody and implement the systems and processes herein described. It is important to understand that embodiments can be provided in many alternate forms and should not be construed as limited to the examples set forth herein.

[0049] Accordingly, while embodiment can be modified in various ways and take on various alternative forms, specific embodiments thereof are shown in the drawings and described in detail below as examples. There is no intent to limit to the particular forms disclosed. On the contrary, all modifications, equivalents, and alternatives falling within the scope of the appended claims should be included.

[0050] [Fig 1] shows a first image of the photometry of a high beam module which is to be projected by an automotive lighting device according to the invention. [0051] This first image may be divided into pixels and each pixel may be characterized by its luminous intensity, in a scale from 0, which would correspond to black, to 255, which would correspond to white.

[0052] [Fig 2] shows a portion of such a pixel matrix, called image pattern 1.

Each pixel 11 of this image pattern 1 is characterized by a number according to the aforementioned scale. The compression of this image pattern 1 according to commercially available softwares would offer a compression rate lower than 50%, which is unacceptable by some car manufacturers.

[0053] [Fig 3a] shows a portion of a variation matrix 2. This variation matrix 2 is obtained by a simple formula: D (i, 1 ) = F (i, 1 ) for j > 1 , D (i, j) = F (i, j) - F (i, j-1 ) wherein D is the variation matrix shown in [Fig 3] and F is the image pattern shown in [Fig 2] The indexes i and j are referred to the row and column inside the matrix.

[0054] Due to the light distribution, it is very common that this variation matrix may have negative values. To avoid the use of a sign bit, the variation matrix is normalized by the addition of a constant value to all the pixel values of said variation matrix.

[0055] If the variation matrix of [Fig 3a] has values comprised between -6 and 9, by the addition of 6 to the values of the variation matrix (except to those of the first column), the normalized variation matrix will have values from 0 to 15.

[0056] Following the aforementioned formulae, this normalized variation matrix would be obtained in the following way:

N (i, 1) = D (i, 1) for j > 1 , N (i, j) = D (i, j) + m-l (i, j), where N is the normalized variation matrix, m is the absolute value of the minimum value of the variation matrix (in this case, it would be 6, since the minimum value of the variation matrix would be -6, and the absolute value is 6), and I is the identity matrix.

[0057] [Fig 3b] shows an example of a normalized variation matrix 3, following the example of [Fig 3a].

[0058] As a consequence, compared to the original image pattern of [Fig 2], which needed 8 bits to characterize each pixel, the normalized variation matrix 3 only needs four bits per pixel. This difference is integrated in the matrix characterization before compressing the data.

[0059] Once these steps are carried out (obtention of the variation matrix, normalization to zero and integration of the new bit size) the data is compressed, thus creating compressed data.

[0060] The compression rate of these data is much higher than in the event the same compression method was applied to the original. As a consequence, this compressed data may be sent to the light module compelling with restrictive conditions about the bandwidth.

[0061] [Fig 4] shows an automotive lighting device according to the invention, this lighting device comprising: - a light module 4 comprising a plurality of LEDs 5;

- a control unit 6 to carry out the compression steps described in the previous figures, generating the compressed data; and

- a processor unit 7, the processor unit 7 being configured to decompress the compressed data, this processor unit being located in the light module 4. [0062] This light module would achieve a very good quality projection with an improved transmission bandwidth. ]

Claims

[Claim 1] [Method for managing image data in an automotive lighting device (10), the method comprising the steps of:

- providing an image pattern (1) with a plurality of light pixels (11);

- defining a variation pattern (2) with a plurality of light pixels (21), wherein a pixel (21) of the variation pattern (2, 3) is related to the difference of luminous intensity between two pixels (11) of the image pattern (1);

- compress the variation pattern (2, 3), thus creating a compressed variation pattern; and

- send the compressed variation pattern to a light module (4).

[Claim 2] Method according to claim 1, wherein the light pixels (11) of the image pattern (1) are greyscale pixels, and more particularly, the luminous intensity of each pixel (11) is according to a scale from 0 to 255.

[Claim 3] Method according to any of claims 1 or 2, wherein a pixel of the variation pattern (2, 3) is related to the difference of luminous intensity between two neighbouring or adjacent pixels (11) of the image pattern (1).

[Claim 4] Method according to claim 3, wherein a pixel (21) of the variation pattern (2, 3) is related to the difference of luminous intensity between a pixel (11) of the image pattern (1) which is in the same position and the adjacent pixel.

[Claim 5] Method according to claim 4, wherein the variation pattern is related to the image pattern following the formulae:

[Claim 6] Method according to any of the preceding claims, further comprising the step of normalizing the variation pattern by adding a compensation value to at least some of the pixels of the variation pattern so that the lower value of the normalized variation pattern (3) is equal or greater than zero, and the step of compressing the variation pattern (2, 3) is applied over the normalized variation pattern (3).

[Claim 7] Method according to any of the preceding claims, wherein before the step of compressing the variation pattern (2, 3), the number of bits necessary to characterize a pixel is integrated.

[Claim 8] Method according to any of the preceding claims, further comprising the step of decompressing the compressed variation pattern.

[Claim 9] Method according to any of the preceding claims, wherein the variation pattern (2, 3) is related only to a particular portion of the image pattern (1). [Claim 10] Automotive lighting device

(10) comprising:

- a light module (4) comprising a plurality of light sources (5); and

- a control unit (6) to carry out the steps of a method according to any of the preceding claims.

[Claim 11 ] Automotive lighting device (10) according to claim 10, wherein the light module (4) further comprises a processor unit (7), the processor unit (7) being configured to decompress the compressed variation pattern.

[Claim 12] Automotive lighting device (10) according to any of claims 10 or 11 , wherein the light sources (5) are solid-state light sources, such as LEDs. ]