27. The computer program product of claim 26 , further operable to cause data processing apparatus to perform operations comprising: analyzing a portion of a composite face to identify a direction of a facial characteristic; determining, for a corresponding image portion associated with the scaled candidate face, a sharpness value across the facial characteristic and a sharpness value along the facial characteristic; and generating the sharpness measure based on a difference between the sharpness value across the facial characteristic and the sharpness value along the facial characteristic.
27. The computer program product of claim 26 , further operable to cause data processing apparatus to perform operations comprising: analyzing a portion of a composite face to identify a direction of a facial characteristic; determining, for a corresponding image portion associated with the scaled candidate face, a sharpness value across the facial characteristic and a sharpness value along the facial characteristic; and generating the sharpness measure based on a difference between the sharpness value across the facial characteristic and the sharpness value along the facial characteristic. 28. The computer program product of claim 27 , further operable to cause data processing apparatus to perform operations comprising: selecting the portion of the composite face based on a level of image detail.