Information processing apparatus, information processing method, and program
There is provided an image archiving method for use with a writing target, comprising the steps of receiving a series of captured images of the writing target, detecting difference between first and second candidate received images separated by a predetermined period of time, where additive differences are indicative of writing and subtractive differences are indicative of erasure; upon detecting subtractive difference, temporarily retaining a last candidate image captured prior to the detection, and detecting whether the subtractive difference relative to the retained image exceeds a subtraction threshold amount; and if so, then storing the retained image.
1. An information processing apparatus, comprising:
an input interface to receive a series of captured images of a writing target; and
processing circuitry configured to
detect a difference between first and second candidate received images of the received series of captured images, the first and second candidate received images being captured at different times, wherein an additive difference is indicative of writing and a subtractive difference is indicative of erasure;
in response to detecting an additive difference, detect whether an additive difference between the first and second candidate received images exceeds a first addition threshold amount; and
in response to detecting that the additive difference between the first and second candidate received images exceeds the first addition threshold amount at a first time, determine, as a particular recording image, a particular candidate received image, of subsequent candidate received images received after the first time, corresponding to a second time, occurring after the first time, when the additive difference between the particular candidate received image and another of the subsequent candidate received images falls below a second addition threshold amount.
2. The information processing apparatus of claim 1 , further comprising a memory, wherein the processing circuitry is further configured to store the determined particular recording image in the memory.
3. The information processing apparatus of claim 1 , wherein the processing circuitry is further configured to estimate a change rate based on the detected difference between the first and second candidate received images.
4. The information processing apparatus of claim 3 , wherein the processing circuitry is further configured to, in response to detecting the additive difference, determine, as a certain recording image, a certain candidate received image corresponding to a time when the estimated change rate previously exceeds one or more of (1) a noise-floor threshold, (2) a predetermined gradient of the change rate, and (3) a writing threshold corresponding to a predetermined amount of writing.
5. The information processing apparatus of claim 1 , wherein the processing circuitry is further configured to detect a starting point for the additive difference by detecting motion of an item of stationery associated with an act of writing.
6. The information processing apparatus of claim 1 , wherein a predetermined period of time between the first and second candidate received images received by the input interface is longer than an image capture period.
7. The information processing apparatus of claim 1 , wherein the processing circuitry is further configured to:
store a video sequence of the writing target, from which the first and second candidate received images were obtained; and
associate, with the stored video sequence, timestamps corresponding to timings within the video sequence at which the first and second candidate received images were stored.
8. An information processing method, comprising:
receiving a series of captured images of a writing target; and
detecting a difference between first and second candidate received image of the received series of captured images, the first and second candidate received images being captured at different times, wherein an additive difference is indicative of writing and a subtractive difference is indicative of erasure;
in response to detecting an additive difference, detecting whether an additive difference between the first and second candidate received images exceeds a first addition threshold amount; and
in response to detecting that the additive difference between the first and second candidate received images exceeds the first addition threshold amount at a first time, determining, as a particular recording image, a particular candidate received image, of subsequent candidate received images received after the first time, corresponding to a second time, occurring after the first time, when the additive difference between the particular candidate received image and another of the subsequent candidate received images falls below a second addition threshold amount.
9. The information processing method of claim 8 , further comprising storing, in a memory, the determined particular recording image.
10. The information processing method of claim 8 , further comprising estimating a change rate based on the detected difference between the first and second candidate received images.
11. The information processing method of claim 10 , further comprising, in response to detecting the additive difference, determining, as a certain recording image, a certain candidate received image corresponding to a time when the estimated change rate previously exceeds one or more of (1) a noise-floor threshold, (2) a predetermined gradient of the change rate, and (3) a writing threshold corresponding to a predetermined amount of writing.
12. The information processing method of claim 8 , further comprising detecting a starting point for the additive difference by detecting motion of an item of stationery associated with an act of writing.
13. The information processing method of claim 8 , wherein a predetermined period of time between the first and second candidate received images received in the receiving step is longer than an image capture period.
14. The information processing method of claim 8 , further comprising:
storing a video sequence of the writing target, from which the first and second candidate received images were obtained; and
associating, with the stored video sequence, timestamps corresponding to timings within the video sequence at which the first and second candidate received images were stored.
15. A non-transitory computer-readable medium storing a program that, when executed by processing circuitry, causes the processing circuitry to perform an information processing method, comprising:
receiving a series of captured images of a writing target; and
detecting a difference between first and second candidate received image of the received series of captured images, the first and second candidate received images being captured at different times, wherein an additive difference is indicative of writing and a subtractive difference is indicative of erasure;
in response to detecting an additive difference, detecting whether an additive difference between the first and second candidate received images exceeds a first addition threshold amount; and
in response to detecting that the additive difference between the first and second candidate received images exceeds the first addition threshold amount at a first time, determining, as a particular recording image, a particular candidate received image, of subsequent candidate received images received after the first time, corresponding to a second time, occurring after the first time, when the additive difference between the particular candidate received image and another of the subsequent candidate received images falls below a second addition threshold amount.
16. The non-transitory computer-readable medium of claim 15 , wherein the method further comprises storing, in a memory, the determined particular recording image.
17. The non-transitory computer-readable medium of claim 15 , wherein the method further comprises estimating a change rate based on the detected difference between the first and second candidate received images.
18. The non-transitory computer-readable medium of claim 17 , wherein the method further comprises, in response to detecting the additive difference, determining, as a certain recording image, a certain candidate received image corresponding to a time when the estimated change rate previously exceeds one or more of (1) a noise-floor threshold, (2) a predetermined gradient of the change rate, and (3) a writing threshold corresponding to a predetermined amount of writing.
19. The non-transitory computer-readable medium of claim 15 , wherein the method further comprises detecting a starting point for the additive difference by detecting motion of an item of stationery associated with an act of writing.
20. The non-transitory computer-readable medium of claim 15 , wherein a predetermined period of time between the first and second candidate received images received in the receiving step is longer than an image capture period.