Digital imaging device with enhanced dynamic range and operating method as well as data processing circuit thereof

1. An operating method of a digital imaging device, the digital imaging device comprising a sensor array, an analog-to-digital converter and a digital back end, the sensor array comprising a plurality of black pixels for outputting black pixel data and a plurality of normal pixels for outputting normal pixel data, and the sensor array sequentially outputting a first frame and a second frame, the operating method comprising:

determining, by the digital back end, a gain and an initial calibration value for processing the black pixel data and the normal pixel data of the first frame to cause the analog-to-digital converter to output digital black pixel data and digital normal pixel data;

calculating, by the digital back end, a data offset according to the digital black pixel data;

determining, by the digital back end, a dynamic adjustment scale for amplifying the digital normal pixel data;

calculating, by the digital back end, a calibration value according to the gain, the data offset and the dynamic adjustment scale;

adjusting the gain, by the digital back end, according to the dynamic adjustment scale; and

processing, by the digital back end, the black pixel data and the normal pixel data of the second frame according to the calculated calibration value and the adjusted gain.

2. The operating method as claimed in claim 1 , wherein the initial calibration value is 0.

3. The operating method as claimed in claim 1 , wherein the dynamic adjustment scale is determined according to a look-up table.

4. The operating method as claimed in claim 1 , wherein the dynamic adjustment scale is determined according to an iteration algorithm.

5. The operating method as claimed in claim 1 , wherein the second frame is a next frame of the first frame.

6. The operating method as claimed in claim 1 , wherein the calculating the calibration value comprises:

calculating a maximum calibration value and a minimum calibration value according to the gain, the data offset and the dynamic adjustment scale; and

calculating an average value of the maximum calibration value and the minimum calibration value as the calibration value.

7. The operating method as claimed in claim 1 , wherein the adjusting comprises:

multiplying the gain by a multiple, which is a quotient of the dynamic adjustment scale divided by the gain.

8. The operating method as claimed in claim 1 , wherein the calculating the data offset comprises:

calculating a difference value between an average value of the digital black pixel data and a reference value as the data offset.

9. The operating method as claimed in claim 1 , further comprising:

amplifying the black pixel data and the normal pixel data of the first frame with the gain; and

subtracting the initial calibration value from the amplified black pixel data and the amplified normal pixel data to generate amplified and calibrated black pixel data and amplified and calibrated normal pixel data, respectively;

converting, by the analog-to-digital converter, the amplified and calibrated black pixel data to the digital black pixel data; and

converting, by the analog-to-digital converter, the amplified and calibrated normal pixel data to the digital normal pixel data.

10. The operating method as claimed in claim 1 , wherein the dynamic adjustment scale is between 1.5-1.9.

11. A digital imaging device, comprising:

a sensor array comprising a plurality of black pixels and a plurality of normal pixels, wherein the black pixels are configured to output black pixel data, the normal pixels are configured to output normal pixel data and the sensor array is configured to sequentially output a first frame and a second frame;

an analog front end configured to output digital black pixel data and digital normal pixel data converted from the black pixel data and the normal pixel data of the first frame processed by a gain and an initial calibration value; and

a digital back end configured to

determine the gain and the initial calibration value,

calculate a data offset according to the digital black pixel data,

determine a dynamic adjustment scale for amplifying the digital normal pixel data,

calculate a calibration value according to the gain, the data offset and the dynamic adjustment scale,

adjust the gain according to the dynamic adjustment scale, and

process the black pixel data and the normal pixel data of the second frame according to the calculated calibration value and the adjusted gain.

12. The digital imaging device as claimed in claim 11 , wherein the initial calibration value is 0.

13. The digital imaging device as claimed in claim 11 , wherein the dynamic adjustment scale is determined according to a look-up table.

14. The digital imaging device as claimed in claim 11 , wherein the dynamic adjustment scale is determined according to an iteration algorithm.

15. The digital imaging device as claimed in claim 11 , wherein the second frame is a next frame of the first frame.

16. The digital imaging device as claimed in claim 11 , wherein the dynamic adjustment scale is between 1.5-1.9.

17. A data processing circuit for processing black pixel data and normal pixel data received from a sensor array, the data processing circuit comprising:

an analog front end configured to output digital black pixel data and digital normal pixel data converted from the black pixel data and the normal pixel data processed by a gain and an initial calibration value; and

a digital back end coupled downstream of the analog front end, and configured to

determine the gain and the initial calibration value,

calculate a data offset according to the digital black pixel data,

determine a dynamic adjustment scale for amplifying the digital normal pixel data,

calculate a calibration value according to the gain, the data offset and the dynamic adjustment scale, and

adjust the gain according to the dynamic adjustment scale.

18. The data processing circuit as claimed in claim 17 , wherein the initial calibration value is 0.

19. The data processing circuit as claimed in claim 17 , wherein the dynamic adjustment scale is determined according to a look-up table.

20. The data processing circuit as claimed in claim 17 , wherein the dynamic adjustment scale is determined according to an iteration algorithm.