An image processing device includes an image sensor including a pixel array that includes a first pixel group, and a correlated double sampling circuit. The first pixel group includes a first plurality of normal pixels, a second plurality of normal pixels, and at least one first phase detection pixel. The correlated double sampling circuit is configured to generate first video data, based on charges of the first plurality of normal pixels, generate second video data, based on charges of the second plurality of normal pixels, and generate first phase detection data, based on an output of the at least one first phase detection pixel. The image processing device further includes an image signal processor configured to apply a first weight to the generated first video data, and apply a second weight to the generated second video data.