Jeff Tyrrill—CSE455—Project 1

Jeff Tyrrill
University of Washington
CSE 455
2004 Winter Quarter

The Artifact

Those of you who have seen Back to the Future know what will happen next.

Making

The original frame:

The original movie film frame

I used the image scissor program, created for this project, to create a contour of the desired parts of the image. The program snaps the selection to edges automatically. The program saves both a snapshot of the contour, and a transparency mask to be used with Photoshop:

Transparency mask for original film frame

I selected a suitable photo of a roof of a generic building. A friend took hundreds of high resolution photos on a recent trip to New York, so there were plenty to pick from. I picked this one because it was close enough to the building at a good enough resolution, and it had a good top-down angle. Already, it has been scaled up by a factor of three.

As I had taken the movie image from the DVD, I adjusted the aspect ratio because DVD pixels are not square (especially with anamorphic encoding, as this movie is), but computer image pixels are. I'll have to admit that at the time, I didn't do the exact calculation to get the scale factor—I just picked a number that looked good: scale up the horizontal direction (only) by 1.2. It turns out that this is close to the exact amount of 1.185. (DVD resolution, and the original screen shot image, are 720*480. Multiplying 720 by 1.185 gives 853 horizontal pixels. 853 / 480 is 1.777, or 16:9, the aspect ratio of an anamorphic widescreen image from DVD.)

In Photoshop, I used the paint, line, fill, color pick, and blur tools to fill in the parts of the image that were missing from the movie film frame. As can be seen above, tables in the movie scene blocked parts of the equipment, so these were drawn in. The sides and top of the equipment were also drawn in. I blurred, and then, used a filter to add a bit of noise to the parts I drew in so they look more similar to the parts visible in the frame. Finally—and this one single touch-up helped immensely in making the composite look natural—I skewed the bottom of the image, which was the cut-off cardboard boxes, to have the same angle as the lower ridge on the roof of the building. This causes a bit of a discontinuity with the flap of the cardboard box in front of Marty's leg, but you didn't notice until I pointed it out, did you?

I used "auto levels" individually on both the movie image layer and the background layer, so the differing brightness and contrast in the two photos matched more closely.