Cameras are widely used by average consumers, hobbyists, and professionals. While film-based photography has been popular for decades, digital cameras are quickly becoming the principal photography device for most households. Indeed, many electronic devices are being integrated with digital camera functionality, and traditional film cameras are being fitted with electronic features as well. For example, mobile telephones which include a digital camera are becoming increasingly common.
A well known photographic method involves utilizing a different depth of field (“DOF”) to produce an image with the subject slightly out of focus, which is sometimes called “soft-focus” or portrait-style. Depth of field is the distance between the farthest and nearest points which are in focus. This can also be identified as the zone of acceptable sharpness in front of and behind the subject, to which the lens is focused on. While “acceptably sharp” is a somewhat subjective standard, it has been defined mathematically by those skilled in the art. In general, the suggested photographic procedure is to place ⅓ of the DOF in front of the subject and ⅔ behind the subject.
The DOF is determined from several variables and is a function of the size of the image capturing device (i.e. film or photoelectric sensor), aperture, focal length, and distance to the subject. In portrait photography, it is common to utilize a shallow DOF in order to place the subject in sharper contrast to the surroundings.
Film-based cameras have utilized various methods such as special lenses, filters, or even gels to achieve a shallower DOF. However, since DOF is inversely proportional to the size of the image capturing device, film-based cameras have traditionally had much greater control over DOF than digital cameras, due at least in part to the relative large size of film in comparison to photoelectric sensors used in digital cameras. Thus, the relatively small size of the image capturing device used in digital cameras has traditionally resulted in a large DOF. Therefore, there is a need for a method and apparatus to allow for a shallower DOF, such that a user can employ various photographic techniques such as portrait photography.