Sampling and readout of an image sensor

A CMOS image sensor or other type of image sensor comprises an array of pixels arranged in rows and columns, with the columns being separated into groups each comprising two or more columns that share a common output. The image sensor further comprises sampling and readout circuitry that includes, for each group of columns in the pixel array, a corresponding set of two or more column circuits. The sampling and readout circuitry is configured to sample the common output for each group of columns independently into one of the column circuits associated with that group, and to read out the common output for each group of columns as previously sampled into another of the column circuits associated with that group. The image sensor may be implemented in a digital camera or other type of image capture device.