Image sensors with pixel array sub-sampling capabilities
View Patent ↗An image sensor may include an array of image pixels arranged according to a predetermined pattern. A 3-by-3 pixel sub-sampling method is provided that supports a high-speed sub-resolution video mode. The 3-by-3 sub-sampling method may involve organizing the image pixel array into groups, each of which contains a 3-by-3 array of nine pixels. Image pixels at the four corners of each group may be sampled and combined to form a final output. Final outputs produced from each group may form a sub-sampled array that is used by the sub-resolution video mode.
1. A method of operating an image sensor having an array of image sensor pixels, comprising:
reading data from a first plurality of image sensor pixels arranged along a first row in the array;
reading data from a second plurality of image sensor pixels arranged along a second row in the array, wherein at least one image sensor pixel in the first plurality of image sensor pixels and at least one image sensor pixel in the second plurality of image sensor pixels are arranged along a common column in the array; and
producing an output signal by combining the data read from the first plurality of image sensor pixels with the data read from the second plurality of image sensor pixels, wherein the data from the first and second pluralities of image sensor pixels are read without reading any data from a third plurality of image sensor pixels arranged along a third row in the array that is interposed between the first and second rows, and wherein the first, second, and third pluralities of image sensor pixels form a three-by-three group of image sensor pixels in the array.
2. The method defined in claim 1 , further comprising:
with a data converting circuit, converting the output signal into digital data.
3. The method defined in claim 1 , wherein reading data from the first plurality of image sensor pixels comprises reading data from first and second image sensor pixels that are formed in non-adjacent columns.
4. The method defined in claim 1 , further comprising:
storing the data read from the first plurality of image sensor pixels in a first storage element;
storing the data read from the first plurality of image sensor pixels in a second storage element, wherein producing the output signal comprises combining the data stored in the first storage element with the data stored in the second storage element.
5. The method defined in claim 1 , wherein producing the output signal comprises producing a reset output signal, the method further comprising:
reading additional data from the first plurality of image sensor pixels arranged along the first row in the array;
reading additional data from the second plurality of image sensor pixels arranged along the second row in the array; and
producing an image output signal by combining the additional data read from the first plurality of image sensor pixels with the additional data read from the second plurality of image sensor pixels.
6. The method defined in claim 5 , further comprising:
generating a final output signal based on the reset output signal and the image output signal.
7. A method for operating an image sensor having an array of image sensor pixels arranged in rows and columns, comprising:
during a first time period, generating a first set of signals using a plurality of column amplifiers in non-adjacent columns, wherein the first set of signals comprises a first signal generated by a first image sensor pixel in a first row of the array and a second signal generated by a second image sensor pixel in the first row of the array;
during a second time period, generating a second set of signals using the plurality of column amplifiers, wherein the second set of signals comprises a third signal generated by a third image sensor pixel in a second row of the array and a fourth signal generated by a fourth image sensor pixel in the second row of the array; and
during a third time period, generating a combined signal by combining the first, second, third, and fourth signals and converting the combined signal with a data converter.
8. The method defined in claim 7 , wherein the first set of signals and the second set of signals correspond to data accessed from image sensor pixels in non-adjacent rows.
9. The method defined in claim 7 , further comprising:
swapping positions of the first signals so that the first signals are arranged in adjacent columns.
10. The method defined in claim 7 , wherein generating the combined signal comprises generating a combined reset signal, and wherein converting the combined signal comprises converting the combined reset signal to produce a digital reset signal.
11. The method defined in claim 10 , further comprising:
during a fourth time period, generating a third set of signals using the plurality of column amplifiers;
during a fifth time period, generating a fourth set of signals using the plurality of column amplifiers; and
during a sixth time period, generating a combined image signal by combining the third and fourth sets of signals and converting the combined image signal to produce a digital image signal.
12. The method defined in claim 11 , further comprising:
computing an output signal based on the digital reset signal and the digital image signal.
13. The method defined in claim 11 , wherein the fourth time period occurs after the first time period and before the second time period, and wherein the third time period occurs after the second time period.
14. A system, comprising:
a central processing unit;
memory;
a lens;
input-output circuitry; and
an imaging device, wherein the imaging device comprises:
an image sensor comprising:
a plurality of image sensor pixels that are arranged in rows and columns and that generate image signals;
a plurality of column amplifiers, wherein a given column amplifier in the plurality of column amplifiers corresponds to a given column of image sensor pixels and receives the image signals generated by the given column of image sensor pixels, wherein the given column amplifier produces first signals based on the received image signals during a first time period and produces second signals based on the received image signals during a second time period that is different than the first time period;
routing circuitry that is configured to shift the image signals generated by the given column of image sensor pixels to a column amplifier that corresponds to a column of image sensor pixels other than the given column; and
a data converter operable to convert a combined signal that includes both the first and second signals, wherein the combined signal is used to generate an image based on a sub-sampling of the plurality of pixels.
15. The system defined in claim 14 , further comprising:
switching circuitry operable to couple the plurality of column amplifiers to the data converter.
16. The system defined in claim 14 , wherein the first signals are generated using column amplifiers in non-adjacent columns.
17. The system defined in claim 14 , wherein the first and second signals correspond to data accessed from image sensor pixels in non-adjacent rows.
18. The system defined in claim 14 , wherein the plurality of image sensor pixels form an array having a first resolution, and wherein the image generated based on the sub-sampling of the plurality of image sensor pixels has a second resolution that is less than the first resolution.
19. The system defined in claim 14 , wherein generating the image based on the sub-sampling comprises generating the combined signal for only a subset of the image sensor pixels.