1. A method for determining a robust average intensity of pixels from a portion of an image comprising pixels, the method comprising: computing a cumulative density function based upon an intensity histogram of the pixels from the portion of the image; using the cumulative density function to identify pixels to exclude; calculating a robust average intensity using at least some of the pixels that were not excluded; using the robust average intensity to determine an embed pattern in a candidate embedding site comprising pixels; and using the embed pattern to extract a data value from the candidate embedding site.