The 3 As
The majority of digital cameras presently on the market feature what many CE OEMs refer to as the 3As--auto exposure, auto focus, and auto white balance algorithms, that determine camera exposure and processing parameters in automatic mode. In essence, by extending the functionality of Auto-Exposure, Zoran is enabling CE OEMs to add to mainstream, affordable digital cameras a new dimension driven by scene object motion--Auto Mode Selection (AMS).

Zoran's Auto Mode Selection technology increases the percentage of successful photos without asking the user to set the camera's parameters. Zoran's advanced algorithms and hardware logic in the COACH 9 and 10 processors work together to determine the correct exposure, focus, and white balance, while also calculating and adjusting the camera to take into account any motion in the scene or in the handheld camera.

Consumer studies indicate that the most common problem affecting digital photography is unwanted object or hand movements that result in blurred images. But the selection of the best exposure parameters to mitigate unwanted motion image blurring, while maintaining the best balance of image optical sharpness, highlight and shadow detail, and low image noise, can be, and often is, a daunting task, especially when there is no time to make manual camera adjustments before capturing spontaneous moments. Zoran's COACH 9 and 10 processor technology helps capture those precious moments before they are lost.

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Figure 1: COACH 10 block diagram

Zoran integrated its advanced image motion stabilization technology into the COACH 9 and 10 processors, for both video and still photos, and linked it with the intelligent selection of exposure parameters that provide the best image possible under all picture-taking conditions. The result is AMS and the highest percentage of remarkably crisp, properly exposed images, from even low-cost digital cameras using the COACH 9 or 10 processors. The COACH AMS technology requires no additional external components, thus OEMs can add this feature with little or no impact to the digital camera bill of materials or system cost.

Next: The next step in AE technology
AMS - The next step in AE technology
While Auto Exposure capability has been available for digital cameras since their inception, it has remained relatively stagnant as a technology and had not been linked with the selection of all the critical exposure parameters. Standard AE simply sets the exposure time, aperture and gain, automatically. The average luminosity is calculated, and then shutter speed and aperture size, as well as gain, are all automatically adjusted. In some digital cameras, users have the ability to override auto exposure settings and further adjust shutter speed and aperture settings before a picture is captured, to achieve a desired depth of field, or freeze motion. This manual feature is useful to determine whether the subject is going to be in motion (such as at a sporting event), or still (such as in a picturesque shot of the moon, a mountain, or a portrait).

Figure 2: COACH 9 digital camera processor package

With the COACH 9 and 10 processors, Zoran has combined all of these processes and handles them rapidly, simultaneously and automatically. The COACH digital processors take into consideration all exposure parameters--such as brightness, depth of field, and noise levels from electronic sensors and additionally folds into the equation the motion of objects in the scene being photographed and "camera shake", caused by the photographer's movement.

The COACH digital camera processors first measure motion, and subsequently determine exposure values. Since there are a series of decisions that have to be made, such as, "what is happening in the picture itself?" the proprietary AMS technology in the COACH processors uniquely defines what is or is not occurring in the picture, whether the camera is or isn't shaking, the scene lighting, and then automatically determines the various camera exposure parameters, that will allow the best picture to be captured.

The user experience with AMS
Newer digital cameras often allow the user to consider the addition of motion (such as at a sporting event), as well as other factors and choose a special camera "mode". The complex, often conflicting, user decisions that need to be made, in order to properly choose the best camera "mode", are all addressed automatically by Zoran's COACH AMS technology.

To provide this ability, Zoran's AMS technology requires little or no external user controls to be incorporated into the already cluttered digital camera user interface. For example, to automatically select the camera settings that could be best described as the "sports mode" of a traditional digital camera, the COACH processor evaluates the motion in the scene to be acquired, checks the lighting conditions, compares these factors with the optical and sensor capabilities offered by the digital camera being used, and appropriately sets the camera's effective shutter speed, aperture size and system sensitivity.

Figure 3: Object movement during photo capture.

Figure 4: Object movement during capture is corrected immediately with Zoran's AMS technology.

Next: Adjusting for camera shake
Camera shake
As a second example, if there is little motion in the scene due to scene object motion or camera jitter, a large amount of light falling on the scene, and the scene is composed of small objects with a fairly uniform colored background, AMS would set the digital camera to the equivalent of the traditional "scenic vista mode".

In this second mode, the shutter speed would be reduced and the commensurate increase in exposure would automatically be compensated for by reducing aperture size or sensor gain. The effect of these settings would be to increase image depth of field to properly capture the scene or reduce overall noise. However, if camera jitter due to user hand movement appears, AMS would set the digital camera settings to be equivalent to "modified scenic vista mode" and a proper balance would be struck between depth of field, exposure time and aperture size, all without user involvement.

Figure 5: "Camera shake" during photo capture.

Figure 6: "Camera shake" corrected immediately by Zoran's AMS technology.

Next: Simplified digital camera design
Simplified digital camera design
From a design standpoint, AMS offers a clean digital camera design.

In summary, Zoran's AMS technology has added a new dimension to its COACH digital camera processors by embedding a combination of software algorithms and hardware logic.

These new solutions provide a clean, efficient, low cost digital camera platform that enables OEMs to deliver affordable new cameras to consumers with the desirable new Auto Mode Selection feature, which significantly improves the quality of photos.

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Figure 7: Top shows typical camera schematics compared to COACH 9 digital camera processor block diagram using AMS technology.

About the author
Ohad Meitav joined Zoran in 1995 when Zoran's digital camera team was formed. Under his leadership, the COACH solution has gained the number one market share position for point-and-shoot digital cameras. Today, as Senior Director Digital Cameras, he is the team leader responsible for assuring that Zoran's customers in China, Japan, Korea and Taiwan deliver their digital camera products quickly to market. Mr. Meitav is an experienced system and VLSI designer who holds a Bachelor of Science degree in Computer Engineering from the Technion in Haifa, Israel. He can be reached at leboss@bluechipllc.com.