Certain methods and systems are described for encoding data in an image. According to an example, a set of metamers under a first set of conditions may be determined that vary under a second set of conditions. These may be used to generate a set of color mappings for a sampled color value, each color mapping being used for a different data value in the data. As such the data values may be detectable when the image is observed under the second set of conditions but not detectable when the image is observed under the first set of conditions.