An image sensor for converting incident light into digital signals is disclosed. In one aspect, the image sensor includes a matrix of light-sensitive pixels arranged in a plurality of pixel columns each having a predetermined lateral extent. The image sensor includes an analog-to-digital converter block including a plurality of analog-to-digital converters (ADCs). Each of the plurality of ADCs includes an analog processing portion adapted to receive at least one analog signal from a pixel column of the matrix and to generate at least one digital signal from the received analog signal. Each of the plurality of ADCs includes a digital processing portion adapted to receive said at least one digital signal from said corresponding analog processing portion. The lateral extent of at least one of the digital processing portions is greater than the lateral extent of its corresponding analog processing portion.