Method and apparatus to correct digital image blur due to motion of subject or imaging device

• US 9,294,674 B2
• Filed: 11/19/2008
• Issued: 03/22/2016
• Est. Priority Date: 03/25/2004
• Status: Active Grant

• Current Assignee: Clear Imaging Research, LLC
• Original Assignee: Clear Imaging Research, LLC
• Inventors: Ozluturk, Fatih M.
• Primary Examiner(s): TSAI, TSUNG YIN
• Application Number:
  US12/274,084
• Publication Number:
  US 20090128657A1
• Time in Patent Office: 2,680 Days
• Field of Search: 382/284, 348/61
• US Class Current: 1/1
• CPC Class Codes: G02B 27/646 compensating for small deviations, e.g. due to vibration or shake movement of one or more optical elements for control of motion blur in cameras, projectors or printers G03B2205/0007; image stabilisation in cameras peculiar to the presence or use of an electronic image sensor H04N23/68
• CPC Class Codes: G06T 2207/10004 Still image; Photographic image
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/20024 Filtering details
• CPC Class Codes: G06T 2207/20201 Motion blur correction
• CPC Class Codes: G06T 2207/20212 Image combination
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51
• CPC Class Codes: H04N 23/62 Control of parameters via user interfaces
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations
• CPC Class Codes: H04N 23/681 Motion detection
• CPC Class Codes: H04N 23/6811 based on the image signal
• CPC Class Codes: H04N 23/6812 based on additional sensors, e.g. acceleration sensors
• CPC Class Codes: H04N 23/683 performed by a processor, e.g. controlling the readout of an image memory
• CPC Class Codes: H04N 23/687 by shifting the lens or sensor position
• CPC Class Codes: H04N 23/80 Camera processing pipelines; Components thereof
• CPC Class Codes: H04N 25/615 involving a transfer function modelling the optical system, e.g. optical transfer function [OTF], phase transfer function [PhTF] or modulation transfer function [MTF]
• CPC Class Codes: H04N 5/265 Mixing

Abstract

Signal processing techniques are applied to digital image data to remove the distortion caused by motion of the camera, or the movement of the subject being photographed, or defective optics, or optical distortion from other sources. When the image is captured, the effect of relative motion between the camera and the subject is that it transforms the true image into a blurred image according to a 2-dimensional transfer function. The 2-dimensional transfer function representing the motion is derived using blind estimation techniques or by using information from sensors that detect the motion. The transfer function is inverted and used to define a corrective filter. The filter is applied to the image and the blur due to the motion is removed, restoring the correct image. Another embodiment uses the transfer function to avoid blur by combining multiple consecutive images taken at a fast shutter speed.

Claims

1. A method of avoiding distortion of images in an imager, the method comprising:

selecting by a user in a viewfinder a subject;

capturing a plurality of sequential images of the subject using an image sensor in the imager and recording the images in a memory, the images being separated by short time intervals;

while the images are being captured,

measuring motion of the imager and motion of the subject of the images,

determining a 2-dimensional transfer function representing the motion of the imager, and

moving the image sensor to counteract the motion of the imager and the motion of the subject;

calculating an inverse of the transfer function;

for each of the images, detecting a location of the subject, wherein the subject is the same in each of the images;

aligning the images based on the locations of the subject in each of the images;

selectively combining the images to obtain a corrected image, wherein the combining includes calculating a pixel value for each image point in the final image based on pixel values of the image point in the combined images; and

filtering the combined image with the inverse of the transfer function.

2. The method of claim 1 wherein detecting the locations of the subject in each image is performed using a pattern recognition technique.

3. The method of claim 1 wherein detecting the locations of the subject in each image is performed using an image segmentation technique.

4. The method of claim 1 wherein detecting the locations of the subject in each image is performed based on a tracking signal that is received from the subject.

5. A camera, comprising:

a viewfinder, configured to display an image and to receive user input designating a subject in the viewfinder;

a recording medium, configured to record a plurality of sequential images, the images being separated by short time intervals;

a memory, configured to store the plurality of images;

a first sensor, configured to measure movement of the camera while the images are being captured, and to determine a 2-dimensional transfer function representing the movement;

a second sensor, configured to measure movement of the subject of the images while the images are being captured, wherein the subject is the same in each of the images;

an image sensor mover, configured to move the image sensor while the images are being captured to counteract the movement of the camera and the movement of the subject; and

a processor, configured to detect a location of the subject in each image, wherein the subject is the same in each of the images, to align the images based on the locations of the subject, and to selectively combine the images to obtain a corrected image, wherein the combining includes calculating a pixel value for each image point in the corrected image based on pixel values of the image point in the combined images, and

wherein the processor is further configured to calculate an inverse of the transfer function and to filter the corrected image with the inverse of the transfer function.

6. The camera of claim 5 wherein the processor is configured to detect the locations of the subject in each image using a pattern recognition technique.

7. The camera of claim 5 wherein the processor is configured to detect the locations of the subject in each image using an image segmentation technique.

8. The camera of claim 5 wherein the processor is configured to detect the locations of the subject in each image based on a tracking signal that is received from the subject.

9. The camera of claim 5 wherein the image sensor mover is an electromagnet.

10. The camera of claim 5 wherein the image sensor mover is a servo.