Vehicular image pickup device and image capturing method

• US 10,516,831 B1
• Filed: 07/12/2018
• Issued: 12/24/2019
• Est. Priority Date: 07/12/2018
• Status: Active Grant

• Current Assignee: Getac Technology Company Limited (MiTAC Holdings Corp.)
• Original Assignee: Getac Technology Company Limited (MiTAC Holdings Corp.)
• Inventors: Tsai, Kun-Yu
• Primary Examiner(s): Hsu, Amy R
• Application Number:
  US16/034,133
• Publication Number:
  US 20200021731A1
• Time in Patent Office: 530 Days
• CPC Class Codes: B60R 11/04 Mounting of cameras operative during drive; Arrangement of controls thereof relative to the vehicle
• 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 25/40 Extracting pixel data from image sensors by controlling scanning circuits, e.g. by modifying the number of pixels sampled or to be sampled

Abstract

A vehicular image pickup device includes an image capturing unit, a fill light unit and a processing unit. The image capturing unit captures driving images. The fill light unit provides a fill light. The processing unit obtains a grayscale quantity distribution of pixels of the driving images on a plurality of grayscale levels. The processing unit numbers the pixels sequentially in the direction from the highest grayscale level to the lowest grayscale level according to the grayscale quantity distribution until the numbering reaches a predetermined number. The processing unit adjusts a fill light intensity of the fill light unit or a gain of the image capturing unit according to the grayscale level of the pixel whose number is the predetermined number.

Claims

1. An image capturing method, comprising the steps of:

capturing a driving image by an image capturing unit;

obtaining a grayscale quantity distribution of a plurality of pixels of the driving image on a plurality of grayscale levels;

numbering the pixels sequentially in a direction from a highest grayscale level to a lowest grayscale level among the grayscale levels according to the grayscale quantity distribution until the numbering reaches a predetermined number; and

adjusting a fill light intensity of a fill light unit or a gain of the image capturing unit according to the grayscale level associated with the pixel numbered with the predetermined number;

wherein the grayscale levels are divided into a first grayscale section, a second grayscale section, a third grayscale section and a fourth grayscale section sequentially in the direction from the highest grayscale level to the lowest grayscale level, and the step of adjusting the fill light intensity or the gain further comprises;

decreasing the fill light intensity or the gain if the grayscale level associated with the pixel numbered with the predetermined number falls inside the first grayscale section;

not adjusting the fill light intensity or the gain if the grayscale level associated with the pixel numbered with the predetermined number falls inside the second grayscale section or the fourth grayscale section; and

increasing the fill light intensity or the gain if the grayscale level associated with the pixel numbered with the predetermined number falls inside the third grayscale section.

2. The image capturing method of claim 1, wherein the step of adjusting the fill light intensity or the gain is followed by the steps of:

calculating, by conversion, a frequency spectrum in the driving images;

detecting a frequency domain location in the frequency spectrum; and

fine-tuning a shutter speed and the gain of the image capturing unit or the fill light intensity according to whether any signal appears at the frequency domain location.

3. The image capturing method of claim 2, wherein the step of fine-tuning the shutter speed and the gain or the fill light intensity further comprises:

not adjusting the shutter speed and the gain or the fill light intensity if a signal appears at the frequency domain location; and

increasing the shutter speed and decreasing the fill light intensity or the gain if no signal appears at the frequency domain location.

4. The image capturing method of claim 2, wherein the frequency domain location is obtained according to the number of pixels on a straight line penetrating the driving images and the number of pixels displaying a character image and aligned in the same direction as the straight line.

5. The image capturing method of claim 2, wherein the product of the shutter speed, the gain and the fill light intensity before and after the fine-tuning remains the same.

6. The image capturing method of claim 1, wherein the step of adjusting the fill light intensity or the gain is followed by the steps of:

retrieving an object image from the driving images;

calculating, by conversion, a brightness distribution of the pixels on a straight line penetrating the object image; and

fine-tuning a shutter speed and the gain of the image capturing unit or the fill light intensity according to a waveform of the brightness distribution.

7. The image capturing method of claim 6, wherein the step of fine-tuning the shutter speed and the gain or the fill light intensity further comprises:

comparing a peak-to-peak value of the waveform with a predetermined difference;

not adjusting the gain, the fill light intensity and the shutter speed if the peak-to-peak value is greater than or equal to the predetermined difference; and

increasing the fill light intensity or the gain if the peak-to-peak value is less than the predetermined difference.

8. The image capturing method of claim 7, wherein the step of fine-tuning the shutter speed and the gain or the fill light intensity further comprises:

comparing a crest value of the waveform with a predetermined peak value;

not adjusting the gain or the fill light intensity and the shutter speed if the crest value is greater than or equal to the predetermined peak value; and

increasing the fill light intensity or the gain if the crest value is less than the predetermined peak value.

9. The image capturing method of claim 7, wherein the step of fine-tuning the shutter speed and the gain or the fill light intensity further comprises:

comparing a trough value of the waveform with a predetermined trough value;

decreasing the fill light intensity or the gain if the trough value is greater than the predetermined trough value; and

not adjusting the gain or the fill light intensity and the shutter speed if the trough value is less than or equal to the predetermined trough value.

10. The image capturing method of claim 6, wherein the step of fine-tuning the shutter speed and the gain or the fill light intensity further comprises:

not adjusting the shutter speed, the gain and the fill light intensity if the number of grayscale pixels of each tangent of the waveform is less than a predetermined number of grayscale pixels; and

increasing the shutter speed if the number of grayscale pixels of any said tangent of the waveform is greater than the predetermined number of grayscale pixels.

11. A vehicular image pickup device, comprising:

an image capturing unit for capturing a driving image;

a fill light unit for providing a fill light; and

a processing unit for obtaining a grayscale quantity distribution of a plurality of pixels of the driving image on a plurality of grayscale levels, numbering the pixels sequentially in a direction from a highest grayscale level to a lowest grayscale level among the grayscale levels according to the grayscale quantity distribution until the numbering reaches a predetermined number, and adjusting a fill light intensity of the fill light unit or a gain of the image capturing unit according to the grayscale level of the pixel whose number is the predetermined number

wherein the grayscale levels are divided into a first grayscale section, a second grayscale section, a third grayscale section and a fourth grayscale section sequentially in the direction from the highest grayscale level to the lowest grayscale level, allowing the processing unit to decrease the fill light intensity or the gain if the grayscale level associated with the pixel numbered with the predetermined number falls inside the first grayscale section, not to adjust the fill light intensity or the gain if the grayscale level associated with the pixel numbered with the predetermined number falls inside the second grayscale section or the fourth grayscale section, and to increase the fill light intensity or the gain if the grayscale level associated with the pixel numbered with the predetermined number falls inside the third grayscale section.

12. The vehicular image pickup device of claim 11, wherein, after adjusting the fill light intensity or the gain, the processing unit calculates, by conversion, a frequency spectrum in the driving images, detects a frequency domain location in the frequency spectrum, and fine-tunes a shutter speed and the gain of the image capturing unit or the fill light intensity according to whether any signal appears at the frequency domain location.

13. The vehicular image pickup device of claim 12, wherein the processing unit does not adjust the shutter speed and the gain or the fill light intensity if a signal appears at the frequency domain location, increases the shutter speed and decreases the fill light intensity or the gain if no signal appears at the frequency domain location.

14. The vehicular image pickup device of claim 12, wherein the processing unit obtains the frequency domain location according to the number of pixels on a straight line penetrating the driving images and the number of pixels displaying a character image and aligned in the same direction as the straight line.

15. The vehicular image pickup device of claim 12, wherein the product of the shutter speed, the gain and the fill light intensity before and after the fine-tuning remains the same.

16. The vehicular image pickup device of claim 11, wherein, after adjusting the fill light intensity or the gain, the processing unit retrieves the object image from the driving images, calculates, by conversion, a brightness distribution of the pixels on a straight line penetrating the object image, and fine-tunes a shutter speed and the gain of the image capturing unit and/or the fill light intensity according to a waveform of the brightness distribution.

17. The vehicular image pickup device of claim 16, wherein the step of fine-tuning the gain or the fill light intensity and the shutter speed according to a waveform of the brightness distribution further comprises:

comparing a peak-to-peak value of the waveform with a predetermined difference;

not adjusting the shutter speed or the gain and the fill light intensity if the peak-to-peak value is greater than or equal to the predetermined difference; and

increasing the fill light intensity or the gain if the peak-to-peak value is less than the predetermined difference.

18. The vehicular image pickup device of claim 17, wherein the step of fine-tuning the gain or the fill light intensity and the shutter speed according to a waveform of the brightness distribution further comprises:

comparing a crest value of the waveform with a predetermined peak value;

not adjusting the gain or the fill light intensity and the shutter speed if the crest value is greater than or equal to the predetermined peak value; and

increasing the fill light intensity or the gain if the crest value is less than the predetermined peak value.

19. The vehicular image pickup device of claim 17, wherein the step of fine-tuning the gain or the fill light intensity and the shutter speed according to the waveform of the brightness distribution further comprises:

comparing a trough value of the waveform with a predetermined trough value;

decreasing the fill light intensity or the gain if the trough value is greater than the predetermined trough value; and

not adjusting the gain or the fill light intensity and the shutter speed if the trough value is less than or equal to the predetermined trough value.

20. The vehicular image pickup device of claim 16, wherein the processing unit does not adjust the shutter speed, the gain and the fill light intensity if the number of grayscale pixels of each tangent of the waveform is less than a predetermined number of grayscale pixels, and the processing unit increases the shutter speed if the number of grayscale pixels of any said tangent of the waveform is greater than the predetermined number of grayscale pixels.

21. An image capturing method, comprising the steps of:

capturing a driving image by an image capturing unit;

obtaining a grayscale quantity distribution of a plurality of pixels of the driving image on a plurality of grayscale levels;

numbering the pixels sequentially in a direction from a highest grayscale level to a lowest grayscale level among the grayscale levels according to the grayscale quantity distribution until the numbering reaches a predetermined number, wherein the predetermined number corresponds to a number of pixels of a predetermined size of an object image to be detected in the driving image, and wherein the object image is a subset of pixels contained within the driving image; and

adjusting a fill light intensity of a fill light unit or a gain of the image capturing unit according to the grayscale level associated with the pixel numbered with the predetermined number.

22. The image capturing method of claim 21, wherein the grayscale levels are divided into a first grayscale section, a second grayscale section, a third grayscale section and a fourth grayscale section sequentially in the direction from the highest grayscale level to the lowest grayscale level, and the step of adjusting the fill light intensity or the gain further comprises:

decreasing the fill light intensity or the gain if the grayscale level associated with the pixel numbered with the predetermined number falls inside the first grayscale section;

not adjusting the fill light intensity or the gain if the grayscale level associated with the pixel numbered with the predetermined number falls inside the second grayscale section or the fourth grayscale section; and

increasing the fill light intensity or the gain if the grayscale level associated with the pixel numbered with the predetermined number falls inside the third grayscale section.