Patent ID: 9560294
Date: 2017-01-31
CPC Classifications: H01L,H04N

Claim:
1. A method for operating an imaging system having image sensor pixels and temperature sensor pixels arranged in a pixel array, converter circuitry, thermal gradient processing circuitry, and dark current subtraction circuitry, wherein the temperature sensor pixels are formed along a periphery of the pixel array, wherein the periphery has first and second opposing edges and third and fourth opposing edges that extend between the first and second opposing edges, wherein the image sensor pixels and the temperature sensor pixels are arranged in rows and columns in the pixel array, wherein a first temperature sensor pixel is formed on the first edge and a second temperature sensor pixel is formed on the second edge, wherein the first and second temperature sensor pixels are formed in a common row of the pixel array, wherein a third temperature sensor pixel is formed on the third edge and a fourth temperature sensor pixel is formed on the fourth edge, and wherein the third and fourth temperature sensor pixels are formed in a common column of the pixel array, the method comprising: with the image sensor pixels, generating image signals; with the temperature sensor pixels, generating thermal estimate signals; with the converter circuitry, converting the image signals into digital image pixel values and converting the thermal estimate signals into digital thermal estimate values, wherein each of the first, second, third, and fourth temperature sensor pixels generates a corresponding thermal estimate signal that is converted into a corresponding digital thermal estimate signal; with the thermal gradient processing circuitry, generating dark current compensation values based on the digital thermal estimate values, wherein generating the dark current compensation value for a given one of the image sensor pixels comprises interpolating the corresponding digital thermal estimate signals generated by the first, second, third and fourth temperature sensor pixels; and with the dark current subtraction circuitry, generating dark current-corrected digital image pixel values by subtracting the generated dark current compensation values from the digital image pixel values.