IMAGING APPARATUS

• US 20080204571A1
• Filed: 05/02/2008
• Published: 08/28/2008
• Est. Priority Date: 11/04/2005
• Status: Active Grant

• Current Assignee: Arriver Software AB (Qualcomm, Inc.)
• Original Assignee: Autoliv AB (Autoliv Incorporated)
• Inventors: Hall, Peter, Hoglund, Tobias, Hedberg, Ognjan
• Granted Patent: US 8,045,011 B2
• Time in Patent Office: Days
• US Class Current: 348/222.1
• CPC Class Codes: B60R 1/00 Optical viewing arrangements; Real-time viewing arrangements for drivers or passengers using optical image capturing systems, e.g. cameras or video systems specially adapted for use in or on vehicles
• CPC Class Codes: B60R 2300/106 using night vision cameras
• CPC Class Codes: B60R 2300/30 characterised by the type of image processing
• CPC Class Codes: B60R 2300/8053 for bad weather conditions or night vision
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/10048 Infrared image
• CPC Class Codes: G06T 2207/30252 Vehicle exterior; Vicinity of vehicle
• CPC Class Codes: G06T 5/50 using two or more images, e.g. averaging or subtraction
• CPC Class Codes: G06T 5/92 based on global image properties
• CPC Class Codes: H04N 23/81 for suppressing or minimising disturbance in the image signal generation
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

An imaging apparatus including an infrared video camera. The infrared video camera includes a sensor array operable to produce successive video images in the form of pixelated two-dimensional images. The imaging apparatus further comprises a processing arrangement operable to reduce or increase the overall brightness of an image in dependence upon the overall brightness of the pre-enhanced image and the overall brightness of the preceding enhanced image, so that the change in the overall brightness (DC-level) between the enhanced image and the preceding enhanced image is decreased.

Claims

1. An imaging apparatus including an infrared video camera comprising a sensor array and operable to produce successive video images in the form of pixelated two-dimensional images, the imaging apparatus further comprising a processing arrangement operable to reduce or increase an overall brightness of an enhanced image in dependence upon an overall brightness of a pre-enhanced image and an overall brightness of a preceding enhanced image, so that a change in the overall brightness between the enhanced image and the preceding enhanced image is decreased to be less than a difference in overall brightness between the pre-enhanced image and the preceding enhanced image.

2. An imaging apparatus according to claim 1, wherein the brightness level of the enhanced image is adjusted by adding, or multiplying by, a term or factor which is calculated from the overall brightness of the pre-enhanced image and the overall brightness of the preceding image.

3. An imaging apparatus according to claim 1, wherein the output at time t is calculated using

f_out(x,y,t)=f(x,y,t)+γ

·

DC_residual(t) 

 

(1)

where

DC_residual(t)=DC_out(t)−

DC_f(t) 

 

(2)

DC_f(t) being a mean brightness of the pre-enhanced image and

DC_out(t)=(1−

λ

)·

DC_out(t−

1)+λ

·

DC_f(t) 

 

(3)

where γ

is a parameter controlling a strength compensation and λ

is a parameter determining an adaptation rate of the compensation.

8. An apparatus according to claim 1, wherein the overall brightness level is calculated as being, or as being proportional to, an average of signal levels corresponding to each of a plurality of pixels in a frame.

9. An apparatus according to claim 1, wherein the infrared wavelengths observed fall within the far infrared portion of the spectrum.

4. An image enhancement method applicable to infrared video images characterised in that, for each video image, an overall brightness of an enhanced image is reduced or increased in dependence upon an overall brightness of a pre-enhanced image and an overall brightness of the preceding enhanced image.

6. A method according to claim 4, wherein the brightness level of a new image is adjusted by adding, or multiplying by, a term or factor which is calculated from the overall brightness of the pre-enhanced image and the overall brightness of the preceding enhanced image.

7. A method according to claim 4, wherein the output at time t is calculated using

f_out(x,y,t)=f(x,y,t)+γ

·

DC_residual(t) 

 

(1)

where

DC_residual(t)=DC_out(t)−

DC_f(t) 

 

(2)

DC_f(t) being the mean of the pre-enhanced image and

DC_out(t)=(1−

λ

)·

DC_out(t−

1)+λ

·

DC_out(t) 

 

(3)

where γ

is a parameter controlling a strength of compensation and λ

is a parameter determining an adaptation rate of the compensation.

5. An image enhancement method applicable to infrared video images in which at least a fraction of an overall brightness of successive images from an infrared video camera is low-pass filtered with respect to time.