The present work concerns the development of a no-reference demosaicing quality metric. The demosaicing operation converts a raw image acquired with a single sensor array, overlaid with a color filter array, into a full-color image. The most prominent artifact generated by demosaicing algorithms is called zipper. In this work we propose an algorithm to identify these patterns and measure their visibility in order to estimate the perceived quality of rendered images. We have conducted extensive subjective experiments, and we have determined the relationships between subjective scores and the proposed measure to obtain a reliable no-reference metric.