Provided are an image sensor and an image processing device including the same. The image sensor includes: a pixel array including a plurality of pixels arranged in rows and columns and configured to generate pixel signals from the plurality of pixels, a time calculator configured to receive zoom information corresponding to digital zooming, and configured to calculate a row processing time available for processing the pixel signals from the plurality of pixels included in a single row based on the zoom information, a timing generator configured to generate at least one control signal based on the row processing time; and an Analog-to-Digital Converter (ADC) configured to generate pixel data by performing sampling on the pixel signals according to the at least one control signal.