Perfless and cadenceless scanning and digitization of motion picture film
Motion picture film is scanned by high-resolution, continuous sprocketless scanner, producing a first sequence of digital images each representing a plurality of motion picture frames and perforations (perfs) of the film input. The first sequence of images is processed using a processor running an analysis and extraction algorithm, producing a second sequence of images each including a single, edge-stabilized frame of the motion picture.
1. A method comprising:
accessing, by at least one processor, a digital image sequence produced by a sprocketless film scanner from motion picture film in a computer memory, wherein images in the sequence include a plurality of frames;
determining, by the at least processor, a count of perfs and perf image positions in each of the images;
analyzing, by the at least one processor, each of the images using a finite state machine, wherein the analyzing comprises assigning one of a finite number of image states to the each of the images, based at least in part on the count and perf image positions in the each of the images;
extracting, by the at least one processor, at least one frame of the motion picture from the each of the images, based at least in part on the image states assigned by the analyzing to the each of the images; and
preparing, by the at least one processor, a sequence of frames extracted by the extracting sequenced according to the motion picture film.
2. The method of claim 1 , further comprising stabilizing a common edge of every frame in the sequence of frames.
3. The method of claim 1 , further comprising saving the sequence of frames in a computer memory.
4. The method of claim 1 , wherein the determining comprises analyzing a curve of average pixel values generated by averaging pixel values over a rolling sample window.
5. The method of claim 4 , wherein the at least one processor identifies perf locations corresponding to minima of the average pixel values.
6. The method of claim 4 , wherein the at least one processor locates the rolling window relative to the width of the motion picture film at least in part based on an immediately prior one of the each of the images.
7. The method of claim 1 , wherein which frame is extracted from each image depends on which of the image states is assigned to the each image by the analyzing.
8. The method of claim 1 , wherein the at least one processor determines an edge of the extracted frame based on an analysis of an adjacent perf edge.
9. An apparatus comprising at least one processor coupled to a memory, the memory holding program instructions, that when executed by the at least one processor, causes the apparatus to perform:
accessing a digital image sequence produced by a sprocketless film scanner from motion picture film in a computer memory, wherein images in the sequence include a plurality of frames;
determining a count of perfs and perf image positions in each of the images;
analyzing each of the images using a finite state machine, wherein the analyzing comprises assigning one of a finite number of image states to the each of the images, based at least in part on the count and perf image positions in the each of the images;
extracting at least one frame of the motion picture from the each of the images, based at least in part on the image states assigned by the analyzing to the each of the images; and
preparing a sequence of frames extracted by the extracting sequenced according to the motion picture film.
10. The apparatus of claim 9 , wherein the memory holds further instructions for stabilizing a common edge of every frame in the sequence of frames.
11. The apparatus of claim 9 , wherein the memory holds further instructions for the determining at least in by analyzing a curve of average pixel values generated by averaging pixel values over a rolling sample window.
12. The apparatus of claim 11 , wherein the memory holds further instructions for identifying perf locations corresponding to minima of the average pixel values.
13. The apparatus of claim 11 , wherein the memory holds further instructions for locating the rolling window relative to the width of the motion picture film at least in part based on an immediately prior one of the each of the images.
14. The apparatus of claim 9 , wherein the memory holds further instructions for the extracting the frame from each image based on which of the image states is assigned to the each image by the analyzing.
15. The apparatus of claim 9 , wherein the memory holds further instructions for determining an edge of the extracted frame based on an analysis identifying an adjacent perf edge.
16. A method for obtaining a digital image sequence from analog motion picture film, the method comprising:
scanning the motion picture film by a sprocketless scanner, thereby obtaining a digital image sequence;
saving the digital image sequence in a computer memory;
by at least one processor,
determining a count of perfs and perf image positions in each of the images; analyzing each of the images using a finite state machine, wherein the analyzing comprises assigning one of a finite number of image states to the each of the images, based at least in part on the count and perf image positions in the each of the images; and
extracting at least one frame of the motion picture from the each of the images, based at least in part on which of the image states is assigned by the analyzing to the each of the images.
17. The method of claim 16 , wherein the sprocketless scanner has a scanning window per image larger than a frame size of the motion picture film.
18. The method of claim 16 , wherein the scanning window includes at least one row of perfs alongside at least one row of full frames.