IMAGING SYSTEM USING A LENS UNIT WITH LONGITUDINAL CHROMATIC ABERRATIONS AND METHOD OF OPERATING

• US 20130278726A1
• Filed: 01/13/2012
• Published: 10/24/2013
• Est. Priority Date: 01/14/2011
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Siddiqui, Muhammad, Unruh, Christian, Muhammad, Atif, Kamm, Markus
• Granted Patent: US 9,979,941 B2
• Time in Patent Office: Days
• US Class Current: 348/46
• CPC Class Codes: H04N 23/11 for generating image signals from visible and infrared light wavelengths
• CPC Class Codes: H04N 25/61 the noise originating only from the lens unit, e.g. flare, shading, vignetting or "cos4"
• CPC Class Codes: H04N 25/611 Correction of chromatic aberration
• CPC Class Codes: H04N 9/646 for image enhancement, e.g. vertical detail restoration, cross-colour elimination, contour correction, chrominance trapping filters

Abstract

A lens unit of an imaging unit features longitudinal chromatic aberration. From an imaged scene, an imaging sensor unit captures non-color-corrected first images of different spectral content. An intensity processing unit computes broadband luminance sharpness information from the first images on the basis of information descriptive for imaging properties of the lens unit. A chrominance processing unit computes chrominance information on the basis of the first images. A synthesizing unit combines the computed chrominance and luminance information to provide an output image having, for example, extended depth-of-field. The imaging unit may be provided in a camera system, a digital microscope, as examples.

Claims

1. An imaging system comprising

an imaging unit that comprises a lens unit showing longitudinal chromatic aberration and an imaging sensor unit configured to generate, from an imaged scene, non-colour-corrected first images of different spectral content,

a intensity processing unit configured to compute broadband luminance sharpness information on the basis of the first images and information descriptive for imaging properties of the lens unit,

a chrominance processing unit configured to compute chrominance information on the basis of the first images, and

a synthesizing unit configured to combine the chrominance and broadband luminance sharpness information to provide an output image.

2. The imaging system of claim 1, wherein

the imaging sensor unit is configured to output a greyscale image and the intensity processing unit is configured to compute the broadband luminance sharpness information on the basis of the greyscale image.

3. The imaging system of claim 1, wherein

the imaging unit is configured to supply at least two colour-filtered first images,

the intensity processing unit comprises a luminance pre-processing unit configured to generate a greyscale image or intensity function from the at least two colour-filtered first images, and

the intensity processing unit is configured to compute the broadband luminance sharpness information on the basis of the generated greyscale image.

4. The imaging system of claim 2, wherein the intensity processing unit comprises

controllable weighting units, each weighting unit configured to apply a selectable weight to one of the first images, and

a weighting control unit configured to select the weights for the weighting units in response to a user input or an evaluation of the first images.

5. The imaging system of any of claim 2, wherein

the intensity processing unit comprises a deconvolution unit configured to compute the broadband luminance sharpness information by deconvolving the greyscale image with a point spread function descriptive for the lens unit.

6. The imaging system of claim 1, wherein

the chrominance processing unit comprises a depth map estimator configured to generate a depth map from the first images.

7. he imaging system of claim 6, wherein

the chrominance processing unit further comprises a correction unit configured to correct chromatic aberrations in the first images to provide corrected images from the first images.

8. The imaging system of claim 1, wherein

the synthesizing unit is configured to transfer sharpness information from the broadband luminance sharpness information into the corrected images.

9. The imaging system of any of claim 7, wherein

the synthesizing unit is configured to transfer sharpness information from the broadband luminance sharpness information into the corrected images on the basis of the depth map.

10. he imaging system of claim 1, wherein

the synthesizing unit is configured to interleave corrected images obtained from the chrominance processing unit and a greyscale image obtained from the intensity processing unit, wherein for each corrected image, a pixel value is updated on the basis of neighbouring pixel values by means of a distance function and a similarity function, the similarity function using information from both the respective corrected image and the greyscale image and determining a weight for the information from the greyscale image.

11. The imaging system of claim 9, wherein

the synthesizing unit is configured to transfer sharpness information further on the basis of a user request, the

the user request concerns one or more items selected from the group including implementation of a 3D-effect, focus distance selection and focus range selection.

12. The imaging system of claim 1, wherein

the imaging system is provided in a camera system, a digital telescope, or a digital microscope.

13. A method of operating an imaging system, the method comprising

capturing at least two non-colour-corrected first images of an imaged scene using a lens unit featuring longitudinal chromatic aberration, the first images having different spectral composition;

computing a broadband luminance sharpness information from the first images on the basis of information descriptive for imaging properties of the lens unit,

computing a chrominance information from the first images to obtain corrected images, and

combining the chrominance and broadband luminance sharpness information to provide an output image using a synthesizing unit.

14. The method of claim 13, wherein

computing the broadband luminance sharpness information comprises deconvolving a greyscale image derived from at least one of the first images using a deconvolution unit and a point spread function descriptive for the lens unit.

15. The imaging method of claim 13, wherein

computing the broadband luminance sharpness information comprises weighting the first images with weights, the weights being selected in response to an illumination condition such that a resulting point spread function is less depth variant than obtained by using equal weights under illumination conditions other than daylight.

16. The imaging method of claim 13, wherein

combining the chrominance and luminance information comprises interleaving the corrected images representing the chrominance information and a greyscale image representing the broadband luminance sharpness information, wherein for each corrected image, a pixel value is updated on the basis of neighbouring pixel values by means of a distance function and a similarity function, the similarity function using information from both the respective corrected image and the greyscale image and determining a weight for the information from the greyscale image.