Freeze Frame
Issue: Volume: 27 Issue: 11 (November 2004)

Freeze Frame

Picture this: In a television commercial for Hewlett-Packard's digital photography line, actors seemingly re-arrange segments of the live action by reaching out and adding or removing a "picture" from the scene.

In the spot, titled "Picture Book," the action is momentarily frozen, mimicking a camera snapshot. Then, actors within the scene physically interact with that "photo," which is actually a frame of video that was cut, or rotoscoped, from the scene when the video was frozen. Next, the frame is composited back into the subsequent action as a photograph.

This plays out in a number of ways. For instance, one segment contains several people who, standing side by side, outline their head and face by holding up a white, hollow frame. The action pauses for less than a second, after which each actor exchanges "looks" with the person next to him or her by first handing off the initial picture frame (now with that actor's portrait inside) to someone else and then "reframing" his or her face with the white-bordered portrait the actor had just received from another. In a different scene, a woman sitting on a park bench reaches up and grabs a "picture" containing the image of a girl who's bouncing on a trampoline in the background. In yet another sequence, a person at a masquerade party "unmasks" guests by removing—and, in some instances, adding—a piece of video containing the party-goer's made-up face.

The face that's behind this creative commercial is that of Francois Vogel, an experimental film director who has extensive experience with digital compositing techniques—which are key to the video effects in the commercial. "Using those [compositing] skills, Vogel did extensive planning and testing before pitching the concept to HP's ad agency, to ensure that it could be done," says Chris Jones, creative director at Zoic Studios, which executed the effects. "As a result, we had a good idea of what he was thinking, and that's rare when you are planning visual effects."
Director and former compositor Francois Vogel followed up last year's acclaimed HP "You" television commercial with "Picture Book," an innovative spot in which the live actors interact with still video images acquired from each scene.

While the effects remained constant in the various scenarios, each one required a different treatment on set and in postproduction, specifically with respect to tracking and compositing. In fact, some segments implement a still video image, while others use several seconds of a video clip.

For instance, in the change-of-identity scene, people are handling what appear to be prints with white borders. But in reality, they are passing around white foam-core frames so that each person would have a physical object to interact with. Later, in postproduction, the artists used Discreet's Combustion to track the physical white frame. Also using Combustion, they rotoscoped a single frame of video from the live action, and with Discreet's Flame, composited that still image inside each white frame.

For the trampoline sequence, the girl was filmed separately against greenscreen, allowing the artists to change her positioning in space to more accurately time her actions with those of the woman, seated on a bench in the foreground. Next, the crew filmed the woman as she reached into the air while pretending to snatch photos and then place them on the bench.

For a tracking reference, the group placed greenscreen paper, which was cut to the proper size, on the bench where the woman would pretend to lay the photos. Then, as they did in the other scenes, the artists tracked the object—in this instance, the paper—using Combustion, rotoscoped the girl from the greenscreen shot, and composited her into the final scene using Flame.
The 60-second commercial incorporates the same underlying postproduction technology—rotoscoping and compositing, using Discreet's Combustion and Flame, respectively—to create a range of visually striking effects.

According to Jones, this greenscreen method not only gave the artists an object to track, but also allowed them to obtain all the practical reflections from the scene, which they later augmented to give the video snapshot a glossy, picture-like look. "We tried to replicate the original scene in the composite, but sometimes we had to depart from reality to make the 'photo' look slightly more creative," he explains.

All nine "picture perfect" scenes in the 60-second commercial contain in-camera effects only, with the exception of the masquerade party. For that, the group used 3D paper created in Alias's Maya, instead of the practical greenscreen paper. "We wanted interesting reflections and a little movement, so we projection-mapped the photograph onto simple geometry and then utilized the more traditional lighting methods available to us within the 3D environment to create a sheen and glossy feel to the prints," explains Jones. "Approaching this sequence from a 3D perspective gave us a lot more flexibility and control than would have been available using Flame's 3D lighting program."

Because the spot would be distributed internationally for broadcast and theatrical release, all the work was completed in HD 25p PAL format, which is rare for television commercials because of its high cost and unforgiving nature. In fact, the most difficult aspect of this project for Zoic was working in that high-end format and handling the large volume of shots. Also, the technical work—tracking, rotoscoping, and finessing—had to be precise in order for the effects to work properly.
For this trampoline scene, artists used greenscreen paper to aid in the subsequent tracking and lighting.

Moreover, the artists had to make sure that when they used still images rather than video clips, the stills looked like photos and not the frozen frames of video that they indeed were. So to avoid the "frozen video" pitfall, the artists used color correction, playing with the contrast and saturation in the still, while for some of the more complex shots like those in the masquerade scene, they used the 3D lighting capabilities in Flame and Combustion to tweak the image.

"The beauty of the spot is its simplicity," Jones says, "and yet it looks impressive."

Karen Moltenbrey is a senior technical editor at Computer Graphics World.