A column parallel ADC circuit includes: plural column ADCs and a digital processing circuit. The plural column ADCs generate respective plural digital counts. The plural column ADCs include a first column ADC and a second column ADC. The first column ADC generates a first digital count according to a first analog signal, and the second column ADC generates a second digital count according to a second analog signal. The first digital count is a difference between a first digital signal and a second digital signal. The first and the second digital signals correspond to the first and the second analog signals respectively. The digital processing circuit generates the plural digital signals, wherein the digital processing circuit generates the first digital signal according to the first digital count and the second digital signal.