A watermark can be permanently and simultaneously added to image data, such as to a video data stream, produced by an image sensor. To produce the watermark in the image data, color filters of a filter array overlying pixels of a sensor array can be arranged in a watermark pattern different from the normal pattern of other color filters of the filter array. The color filters in the watermark pattern can have different colors than other color filters of the filter array. Alternatively or in addition to the watermark pattern of the color filters, a pattern can be formed in a microlens array overlying the filter array. The pattern in the microlens array can have regions devoid of microlenses, microlenses having different shapes, or microlenses having different colors.