# US 5,706,054 A · Method and apparatus for adjusting video data to limit the effects of automatic focusing control on motion estimation video coders > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,706,054 A - Document ID: US5706054A - Status: Granted - Kind: A - Application number: 08/566,015 - Filed: 1995-12-01 - Granted: 1998-01-06 - Earliest claimed: 1995-12-01 - Assignees: Intel Corporation - Inventors: Eric C. Hannah - Web page: https://patentgrep.com/patent/US5706054A ## CPC - H04N 23/959: by adjusting depth of field during image capture, e.g. maximising or setting range based on scene characteristics - G06T 7/254: involving subtraction of images - H04N 5/145: {Movement estimation (for video coding H04N19/51)} - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract A method, and computer program are provided for adjusting motion estimation video data to remove unwanted data generated by an automatic focusing control (AFC) circuit on the video data recorder. One or more edges or fine points in a sequence of motion compensated images is identified. Difference frames composed of pixel differences are generated from the motion compensated images. The difference frames are examined for evidence of AFC action. In the event AFC action is identified, one or more frames of the sequence of difference frames are filtered to remove the AFC effects. The filtered difference frames are encoded. Identification can be made by detecting a component of oscillation in a comparison of summed pixel differences of a sequence of frames. The difference frames may be filtered by reducing the energy level of one or more of the difference frames or by discarding one or more of the difference frames. ## Claims ### Claim 1 A computer-implemented process for encoding video, comprising the steps of: (a) performing motion estimation on a sequence of images to generate a sequence of motion compensated frames and difference frames, the difference frames being comprised of pixel differences; (b) characterizing the effects of automatic focusing control in the sequence of difference frames; (c) adjusting at least one frame of the sequence of difference frames to correct for the characterized effects of automatic focusing control; and (d) encoding the at least one adjusted difference frame. ### Claim 2 (depends on 1) The process of claim 1, wherein step (b) comprises the step of: (1) identifying one or more edges in the sequence of difference frames. ### Claim 3 (depends on 1) The process of claim 1, wherein step (b) comprises the steps of: (1) identifying one or more points in the sequence of difference frames; and (2) generating a binary filtering mask corresponding to the one or more points. ### Claim 4 (depends on 2) The process of claim 2, wherein step (b) further comprises the steps of: (2) generating a binary filtering mask corresponding to the one or more edges; and (3) expanding the binary filtering mask. ### Claim 5 (depends on 2) The process of claim 2, wherein the one or more edges are stationary. ### Claim 6 (depends on 2) The process of claim 2, wherein the sequence of images are first filtered before performing motion estimation to remove effects of automatic gain control. ### Claim 7 (depends on 2) The process of claim 2, wherein step (b) further comprises the steps of: (3) summing the pixel differences in each difference frame which correspond to an identified edge to generate a series of sum signals, each of the series of sum signals corresponding to one of the sequence of difference frames; and (4) analyzing the series of sum signals for the presence of an oscillation. ### Claim 8 (depends on 7) The process of claim 7, wherein step (c) comprises the steps of: (1) extracting an oscillation component from at least one of the series of sum signals; and (2) generating an oscillation ratio for the at least one of the series of sum signals. ### Claim 9 (depends on 8) The process of claim 8, wherein step (c)(2) comprises the step of: (i) dividing the oscillation component by the at least one of the series of sum signals. ### Claim 10 (depends on 8) The process of claim 8, wherein step (c) further comprises the step of: (3) using the oscillation ratio to adjust the corresponding difference frame. ### Claim 11 (depends on 10) The process of claim 10, wherein step (c)(3) comprises the step of: (i) multiplying the pixel differences in the difference frame which correspond to an identified edge by the value of 1 minus the oscillation ratio. ### Claim 12 (depends on 1) The process of claim 1, wherein step (b) further comprises distinguishing the effects of automatic focusing control from the effects of operator controlled focus adjustments. ### Claim 13 (depends on 1) The process of claim 1, wherein step (c) comprises the step of: (1) discarding at least one frame of the sequence of difference frames. ### Claim 14 An apparatus for encoding video, comprising: (a) means for performing motion estimation on a sequence of images to generate a sequence of motion compensated frames and difference frames, the difference frames being comprised of pixel differences; (b) means for characterizing the effects of automatic focusing control in the sequence of difference frames; (c) means for adjusting at least one frame of the sequence of difference frames to correct for the characterized effects of automatic focusing control; and (d) means for encoding the at least one adjusted difference frame. ### Claim 15 (depends on 14) The apparatus of claim 14, wherein means (b): (1) identifies one or more edges in the sequence of difference frames. ### Claim 16 (depends on 14) The apparatus of claim 14, wherein means (b): (1) identifies one or more points in the sequence of difference frames; and (2) generates a binary filtering mask corresponding to the one or more points. ### Claim 17 (depends on 15) The apparatus of claim 15, wherein means (b) further: (2) generates a binary filtering mask corresponding to the one or more edges; and (3) expands the binary filtering mask. ### Claim 18 (depends on 15) The apparatus of claim 15, wherein the one or more edges are stationary. ### Claim 19 (depends on 15) The apparatus of claim 15, wherein the sequence of images are first filtered before performing motion estimation to remove effects of automatic gain control. ### Claim 20 (depends on 15) The apparatus of claim 15, wherein means (b) further: (3) sums the pixel differences in each difference frame which correspond to an identified edge to generate a series of sum signals, each of the series of sum signals corresponding to one of the sequence of difference frames; and (4) analyzes the series of sum signals for the presence of an oscillation. ### Claim 21 (depends on 20) The apparatus of claim 20, wherein means (c): (1) extracts an oscillation component from at least one of the series of sum signals; and (2) generates an oscillation ratio for the at least one of the series of sum signals. ### Claim 22 (depends on 21) The apparatus of claim 21, wherein means (c)(2): (i) divides the oscillation component by the at least one of the series of sum signals. ### Claim 23 (depends on 21) The apparatus of claim 21, wherein means (c) further: (3) uses the oscillation ratio to adjust the corresponding difference frame. ### Claim 24 (depends on 23) The apparatus of claim 23, wherein means (c)(3): (i) multiplies the pixel differences in the difference frame which correspond to an identified edge by the value of 1 minus the oscillation ratio. ### Claim 25 (depends on 14) The apparatus of claim 14, wherein means (b) distinguishes the effects of automatic focusing control from the effects of operator controlled focus adjustments. ### Claim 26 (depends on 14) The apparatus of claim 14, wherein means (c): (1) discards at least one frame of the sequence of difference frames. ### Claim 27 A storage medium encoded with machine-readable computer program code for encoding video, comprising: (a) means for causing a computer to perform motion estimation on a sequence of images to generate a sequence of motion compensated frames and difference frames, the difference frames being comprised of pixel differences; (b) means for causing the computer to characterize the effects of automatic focusing control in the sequence of difference frames; (c) means for causing the computer to adjust at least one frame of the sequence of difference frames to correct for the characterized effects of automatic focusing control; and (d) means for causing the computer to encode the at least one adjusted difference frame. ### Claim 28 (depends on 27) The storage medium of claim 27, wherein means (b): (1) identifies one or more edges in the sequence of difference frames. ### Claim 29 (depends on 27) The storage medium of claim 27, wherein means (b): (1) identifies one or more points in the sequence of difference frames; and (2) generates a binary filtering mask corresponding to the one or more points. ### Claim 30 (depends on 28) The storage medium of claim 28, wherein means (b) further: (2) generates a binary filtering mask corresponding to the one or more edges; and (3) expands the binary filtering mask. ### Claim 31 (depends on 28) The storage medium of claim 28, wherein the one or more edges are stationary. ### Claim 32 (depends on 28) The storage medium of claim 28, wherein the sequence of images are first filtered before performing motion estimation to remove effects of automatic gain control. ### Claim 33 (depends on 28) The storage medium of claim 28, wherein means (b) further: (3) sums the pixel differences in each difference frame which correspond to an identified edge to generate a series of sum signals, each of the series of sum signals corresponding to one of the sequence of difference frames; and (4) analyzes the series of sum signals for the presence of an oscillation. ### Claim 34 (depends on 33) The storage medium of claim 33, wherein means (c): (1) extracts an oscillation component from at least one of the series of sum signals; and (2) generates an oscillation ratio for the at least one of the series of sum signals. ### Claim 35 (depends on 34) The storage medium of claim 34, wherein means (c)(2): (i) divides the oscillation component by the at least one of the series of sum signals. ### Claim 36 (depends on 34) The storage medium of claim 34, wherein means (c) further: (3) uses the oscillation ratio to adjust the corresponding difference frame. ### Claim 37 (depends on 36) The storage medium of claim 36, wherein means (c)(3): (i) multiplies the pixel differences in the difference frame which correspond to an identified edge by the value of 1 minus the oscillation ratio. ### Claim 38 (depends on 27) The storage medium of claim 27, wherein means (b) distinguishes the effects of automatic focusing control from the effects of operator controlled focus adjustments. ### Claim 39 (depends on 27) The storage medium of claim 27, wherein means (c): (1) discards at least one frame of the sequence of difference frames.