METHOD AND APPARATUS FOR MOTION ARTIFACT CORRECTION IN HDR VIDEO

• US 20130033622A1
• Filed: 10/18/2011
• Published: 02/07/2013
• Est. Priority Date: 08/04/2011
• Status: Abandoned Application

• Current Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Original Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Inventors: LI, DONG
• Application Number:
  US13/275,569
• Publication Number:
  US 20130033622A1
• Time in Patent Office: Days
• US Class Current: 348/241
• CPC Class Codes: H04N 23/741 by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors
• CPC Class Codes: H04N 23/81 for suppressing or minimising disturbance in the image signal generation
• CPC Class Codes: H04N 25/589 with different integration times, e.g. short and long exposures

Abstract

A method and system of correcting motion artifacts are provided for video captured from interlaced multiple exposure sensors. The following are included: (a) motion artifacts detection of a pixel area, (b) smoothing of the detected pixel area, and (c) motion artifacts correction. The motion artifacts pixels are detected by comparing the luma difference between a current image frame and a previous image frame; the pixels of the surrounding area are also checked. A smoothing operation is applied to the detected artifacts area, in order to remove isolated pixels and enlarge the detected area. Corrections are then provided using a multistage filter for the luma channel and a mean filter for the chroma channel.

Claims

1. A method of correcting motion artifacts comprising the steps of :

receiving current and previous image frames, each having first and second exposure data at times T1 and T2, respectively;

detecting pixels in a predetermined area having motion artifacts in the first and second exposure data; and

correcting the pixels in the predetermined area.

2. The method of claim 1 wherein the step of detecting includes:

determining that a luma difference between the current image frame and previous image frame is larger than a first predetermined threshold; and

determining that the first exposure includes pixels having intensity values between second and third predetermined thresholds.

3. The method of claim 1 wherein the step of detecting includes:

determining that a total number of pixels in the predetermined area have intensity values greater than a predetermined threshold in either the current image frame, or the previous image frame.

4. The method of claim 1 including the step of :

enlarging the predetermined area having motion artifacts by smoothing the detected pixels.

5. The method of claim 1 wherein the step of correcting includes:

converting values of the detected pixels from an RGB domain into a YCbCr domain; and

filtering the converted values of the detected pixels.

6. The method of claim 5 wherein filtering includes:

providing a filter to a one-dimensional window centered at a pixel located at (x0, y0) in a Y channel.

7. The method of claim 6 wherein the filter includes:

two one-dimensional filters along horizontal and vertical directions with respect to the one-dimensional window.

8. The method of claim 6 wherein the filter includes:

two one-dimensional filters along 135 degree and 45 degree diagonals with respect to the one-dimensional window.

9. The method of claim 5 wherein filtering includes:

providing a filter to a two-dimensional window centered at a pixel located at (x0, y0) in at least one of a Cb channel and a Cr channel.

10. The method of claim 9 wherein the filter provides a mean value of pixel intensities within the two-dimensional window.

11. The method of claim 1 wherein

the time T1 is of greater duration than the time T2, and

the time T2, at least partially, overlaps the time T1.

12. The method of claim 1 wherein the first and second exposure data is interleaved and interpolated to provide separate T1 exposure data and T2 exposure data.

13. A method of correcting motion artifacts in a current image frame comprising the steps of :

exposing the current image frame to first and second interleaved exposures, wherein the first interleaved exposure includes T1 exposure data, and the second interleaved exposure includes T2 exposure data;

detecting pixels in a predetermined area of the current image frame having motion artifacts; and

correcting the pixels in the predetermined area.

14. The method of claim 13 including the step of :

exposing a previous image frame to a previous first and second interleaved exposures; and

wherein the step of detecting includes the steps of;

determining that luma differences between pixels in the current and previous image frames are larger than a first predetermined threshold; and

determining that the T1 exposures data includes pixels having intensity values between second and third predetermined thresholds.

15. The method of claim 14 wherein the steps of determining includes:

counting if the number of pixels in the predetermined area exceeds a fourth threshold value.

16. The method of claim 13 wherein the step of correcting includes:

filtering the detected-pixels using multiple one-dimensional windows centered at (x0, y0).

17. The method of claim 13 wherein the step of correcting includes:

filtering the detected-pixels using a two-dimensional window centered at (x0, y0).

18. An image processor for correcting motion artifacts, the processor executing the steps of:

receiving current and previous image frames, each frame having T1 exposure data and T2 exposure data, wherein the T2 exposure data overlaps the T1 exposure data;

interpolating the T1 exposure data and the T2 exposure data to obtain separate T1 data and T2 data for the current and previous image frames;

selecting pixels in a predetermined area in each of the current and previous image frames;

determining that luma differences between the pixels in the current image frame and the pixels in the previous image frame are larger than a first predetermined threshold;

determining that the T1 data for the current image frame includes pixels in the predetermined area having intensity values between second and third predetermined thresholds; and

correcting the pixels in the predetermined area of the current image frame.

19. The image processor of claim 18 wherein correcting the pixels includes:

smoothing the pixels in the predetermined area of the current image frame; and

filtering the pixels by obtaining mean values calculated along multiple directions in a one-dimensional window centered at (x0, y0).

20. The image processor of claim 18 wherein correcting the pixels includes:

smoothing the pixels in the predetermined area of the current image frame; and

filtering the pixels by obtaining a mean value calculated in a two-dimensional window centered at (x0, y0).