IMAGE RECORDING METHOD AND IMAGE RECORDING APPARATUS

• US 20200137282A1
• Filed: 10/10/2019
• Published: 04/30/2020
• Est. Priority Date: 10/31/2018
• Status: Active Grant

• Current Assignee: Schölly Fiberoptic GmbH (Lonza Group AG)
• Original Assignee: Schölly Fiberoptic GmbH (Lonza Group AG)
• Inventors: Jauss, Joachim
• Granted Patent: US 11,122,212 B2
• Time in Patent Office: Days
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation
• CPC Class Codes: H04N 23/72 Combination of two or more compensation controls
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 23/74 by influencing the scene brightness using illuminating means
• CPC Class Codes: H04N 23/76 by influencing the image signals
• CPC Class Codes: H04N 5/58 in dependence upon ambient light

Abstract

An image recording method (2) and an image recording apparatus (1) are provided for recording a sequence of individual images of a scene (3), wherein, in a first control loop (6), an exposure parameter (8) is set in dependence on a respective brightness value (21) of an individual image, wherein the scene (3) is illuminated using an illumination device (4), wherein, in a second control loop (7), a maximum value (10) of a control range (9) of the exposure parameter (8) in the first control loop (6) is set, wherein the setting of the maximum value (10) is effected in dependence on an exposure variable (11), which indirectly stands for an expected quantity of light incident on an image sensor.

Claims

1. An image recording method (2) for recording a sequence of individual images of a scene (3), the method comprising:

in a first control loop (6), setting an exposure parameter (8) in dependence on a respective brightness value (21) of an individual image,

illuminating the scene (3) using an illumination device (4),

in a second control loop (7), setting a maximum value (10) of a control range (9) of the exposure parameter (8) in the first control loop (6), and

effecting the setting of the maximum value (10) in dependence on an exposure variable (11).

2. The image recording method (2) as claimed in claim 1, wherein the exposure parameter (8) is at least one of a gain (13), an exposure time (14), or a stop setting (15).

3. The image recording method (2) as claimed in claim 1, wherein the exposure variable (11) is a parameter or a combination of two or more parameters from the group including:

a light intensity (16) of the illumination device (4), a stop setting (15), a read time (17) of an image sensor (28), a power consumption (18) of the illumination device (4), a temperature (19) of the illumination device (4), or an actuation signal (20) of the illumination device (4).

4. The image recording method (2) as claimed in claim 3, further comprising at least one of measuring or indirectly determining the light intensity (16) of the illumination device (4) using a light measurement of the light emitted in a direction of the scene (3) by the illumination device (4), and adopting the light intensity (16) in the second control loop (7) as the exposure variable (11).

5. The image recording method (2) as claimed in claim 1, wherein the exposure variable (11) is a light intensity of the illumination device (4), and the illumination device (4) is configured for setting different light intensities (16), and a fixed maximum value (10) of the exposure parameter (8) is assigned to each settable light intensity (16) of the illumination device (4).

6. The image recording method (2) as claimed in claim 1, further comprising setting the maximum value (10) of the control range (9) of the exposure parameter (8) independently of a respective brightness value (21) of an individual image.

7. The image recording method (2) as claimed in claim 6, wherein a setting of the exposure parameter (8) within the limits of the control range (9) in dependence on the respective brightness value (21) of the individual image is effected, and the brightness value (21) is an average value from a plurality of pixel values of an individual image.

8. The image recording method (2) as claimed in claim 7, further comprising measuring the brightness value (21) in a recorded individual image.

9. The image recording method (2) as claimed in claim 1, further comprising increasing the maximum value (10) of the control range (9) of the exposure parameter (8) if a light intensity (16) of the illumination device (4) is reduced.

10. The image recording method (2) as claimed in claim 1, further comprising reducing the maximum value (10) of the control range (9) of the exposure parameter (8) a light intensity (16) of the illumination device (4) is increased.

11. The image recording method (2) as claimed in claim 1, wherein the maximum value (10) of the control range (9) of the exposure parameter (8) remains constant for a constant exposure variable (11).

12. The image recording method (2) as claimed in claim 11, wherein the maximum value (10) of the control range (9) of the exposure parameter (8) remains constant for a constant light intensity (16) of the illumination device (4).

13. The image recording method (2) as claimed in claim 11, wherein the maximum value (10) of the control range (9) of the exposure parameter (8) remains constant for an increase in a distance of an image recording apparatus (1) from the scene (3).

14. An image recording apparatus (1) for recording a sequence of individual images of a scene (3), the image recording apparatus (1) comprising:

an illumination device (4) for illuminating the scene (3),

a closed-loop control unit (5) that is configured for working through a first control loop (6) and a second control loop (7), in which the first control loop (6) comprises setting an exposure parameter (8) in dependence on a respective brightness value (21) of an individual image, and the second control loop (7) comprises setting a maximum value (10) of a control range (9) of the exposure parameter (8) in the first control loop (6) in dependence on an exposure variable (11).

15. The image recording apparatus (1) of claim 14, wherein the image recording apparatus comprises an endoscope (27).

16. The image recording apparatus (1) as claimed in claim 14, wherein the closed-loop control unit is configured to, set an exposure parameter (8) in dependence on a respective brightness value (21) of an individual image in a first control loop (6), illuminate a scene (3) using an illumination device (4), and, in a second control loop (7), set a maximum value (10) of a control range (9) of the exposure parameter (8) in the first control loop (6) and effect the setting of the maximum value (10) in dependence on an exposure variable (11)