Method for evaluating the vision of an individual in predefined brightness conditions

1. A method for evaluating the vision of an individual under predefined luminance conditions, using a screen presenting an image ( 1 ) that includes a background ( 2 ) and characters ( 3 ) to be deciphered appearing on said background ( 2 ), the method comprising:

a step of adjusting a luminance of the background ( 2 ) of the image ( 1 );

a step of adjusting a luminance of the characters ( 3 ) to be deciphered appearing in the image ( 1 ),

said steps of adjusting the luminance of the background and adjusting the luminance of the characters being independent from each other so as to obtain a desired contrast between the background ( 2 ) and the characters ( 3 ); and

evaluating the vision of the individual based on the image characterized by the obtained contrast,

wherein the method further comprises:

a step of adjusting the background to a given grayscale level to obtain a desired background luminance; and

a step of tailoring a grayscale level of the characters to obtain the desired contrast between the background and the characters, thereby to reproduce the image as representative of a night scene to be viewed by the individual.

2. The evaluating method as claimed in claim 1 ,

wherein the image ( 1 ) appearing on the screen is characterized by pixels, and

wherein the luminance of the background ( 2 ) of the image ( 1 ) and the luminance of the characters ( 3 ) is adjusted at a level of said pixels.

3. The evaluating method as claimed in claim 2 , wherein the luminance of the background ( 2 ) of the image ( 1 ) is adjusted to relatively dark grayscale levels in order to simulate the conditions of night vision.

4. The evaluating method as claimed in claim 3 , wherein the luminance of the characters ( 3 ) is adjusted to a grayscale level dependent on the grayscale level of said background ( 2 ), so as to control both the luminance of the background ( 2 ) of the image ( 1 ) and the displayed contrast between the background ( 2 ) and the characters ( 3 ).

5. The evaluating method as claimed in claim 3 , wherein the vision evaluated of the individual is a mesopic vision of the individual.

6. The evaluating method as claimed in claim 3 , wherein the vision evaluated of the individual is a scotopic vision of the individual.

7. The evaluating method as claimed in claim 2 , wherein the luminance of the characters ( 3 ) is adjusted to a grayscale level dependent on the grayscale level of said background ( 2 ), so as to control both the luminance of the background ( 2 ) of the image ( 1 ) and the displayed contrast between the background ( 2 ) and the characters ( 3 ).

8. The evaluating method as claimed in claim 7 , wherein the vision evaluated of the individual is a mesopic vision of the individual.

9. The evaluating method as claimed in claim 7 , wherein the vision evaluated of the individual is a scotopic vision of the individual.

10. The evaluating method as claimed in claim 2 , wherein the background ( 2 ) of the image ( 1 ) and the characters ( 3 ) are in color.

11. The evaluating method as claimed in claim 2 , wherein the vision evaluated of the individual is a mesopic vision of the individual.

12. The evaluating method as claimed in claim 2 , wherein the vision evaluated of the individual is a scotopic vision of the individual.

13. The evaluating method as claimed in claim 1 , wherein the vision evaluated of the individual is a mesopic vision of the individual.

14. The evaluating method as claimed in claim 1 , wherein the vision evaluated of the individual is a scotopic vision of the individual.

15. A device for displaying an image for implementing the method claimed in claim 1 , said device comprising a screen that displays an image ( 1 ) that includes a background ( 2 ) and characters ( 3 ) appearing on said background ( 2 ), and controlling means that independently control the luminance of the background ( 2 ) and the luminance of the characters ( 3 ) to be deciphered by the individual.

16. The displaying device as claimed in claim 15 ,

wherein the image ( 1 ) is formed of pixels, and

wherein said controlling means operate on said pixels in a manner so as to modify the luminance of the background ( 2 ) and of the characters ( 3 ).

17. The displaying device as claimed in claim 16 , wherein the controlling means adjust the grayscale level or the color of each pixel.

18. The displaying device as claimed in claim 15 , wherein said displaying device is a tablet configured to be manipulated by the individual to test the vision of the individual under the predefined luminance conditions.

19. A device that displays an image for evaluating the vision of an individual under predefined luminance conditions, comprising:

a screen that displays an image ( 1 ) that includes a background ( 2 ) and characters ( 3 ) to be deciphered by the individual displayed on said background ( 2 ); and

controlling means that independently control the luminance of the background ( 2 ) and the luminance of the characters ( 3 ),

said controlling means configured for adjusting a luminance of the background ( 2 ) of the image ( 1 ), and adjusting a luminance of the characters ( 3 ) appearing in the image ( 1 ), said adjusting the luminance of the background and adjusting the luminance of the characters being independent from each other so as to obtain a desired contrast between the background ( 2 ) and the characters ( 3 ), and

said controlling means further configured for adjusting the background to a given grayscale level to obtain a desired background luminance, and for adjusting a grayscale level of the characters to obtain the desired contrast between the background and the characters, thereby to reproduce the image as representative of a night scene to be viewed by the individual.

20. The device as claimed in claim 19 ,

wherein the screen is constituted by pixels, the image ( 1 ) being formed by said pixels, and

wherein said controlling means operate on said pixels in a manner so as to modify the luminance of the background ( 2 ) and of the characters ( 3 ) of the image.