An image compensation circuit for an image sensor includes a gain amplifier, a compensation control circuit, a memory and a digital-to-analog converter (DAC). The gain amplifier is used for receiving a plurality of image signals from the image sensor and amplifying the plurality of image signals. The compensation control circuit is used for generating a plurality of compensation values for the plurality of image signals. The memory, coupled to the compensation control circuit, is used for storing the plurality of compensation values. The DAC, coupled to the memory and the gain amplifier, is used for converting the plurality of compensation values into a plurality of compensation voltages, respectively, to compensate the plurality of image signals with the plurality of compensation voltages.