Restoration of color components in an image model
View Patent ↗This invention relates to a method for improving image quality of a digital image captured with an imaging module comprising at least imaging optics and an image sensor, where the image is formed through the imaging optics, the image consisting of at least one color component. In the method degradation information of each color component of the image is found and is used for obtaining a degradation function. Each color component is restored by said degradation function. The image is unprocessed image data, and the degradation information of each color component can be found by a point-spread function. The invention also relates to a device, to a module, to a system and to a computer program product and to a program module.
1. A method comprising:
finding degradation information of each colour component of a digital image captured with an imaging module comprising at least imaging optics and an image sensor, where the image is formed through the imaging optics, said image comprising at least one colour component,
obtaining a degradation function according to the degradation information,
restoring said each colour component by said degradation function, wherein the restoring of said each colour component is performed iteratively by iteratively applying the degradation function using an adapted step size in said iterative restoring, wherein the adapted step size is a function of a local saturation control that modulates a global step size, and
applying a regularization control to each restored colour component, wherein the regularization control limits the restoration effect near regions of the digital image containing pixels that are saturated for a colour component.
2. The method according to claim 1 , wherein said degradation information of each colour component is found by means of a point-spread function.
3. The method according to claim 2 , wherein the restoration is implemented by an iterative restoration function being determined from the point-spread function of each colour component.
4. The method according to claim 1 , wherein said image is unprocessed image data, wherein said restored colour components are further processed by other image reconstruction algorithms.
5. The method according to claim 1 , wherein one of the following colour systems are used: RGB, HSV, OMYK.
6. A model for improving image quality of a digital image, said model being obtainable by a method as claimed in claim 1 .
7. An imaging module comprising imaging optics and an image sensor for forming an image through the imaging optics onto the light sensitive image sensor wherein a model for improving image quality as claimed in claim 6 is related to said imaging module.
8. A device comprising an imaging module as claimed in claim 7 .
9. The device according to claim 8 being a mobile device equipped with communication capabilities.
10. The method according to claim 1 , wherein the adapted step size is given by the following equation:
μ adap (m,n)=β sat (u,m)μ
where μ is the global step size of said iterative restoring, and β sat is the local saturation control that modulates the step size.
11. The method according to claim 10 , wherein β sat is obtained for each colour component for the values associated with pixels of a window surrounding a given pixel location and such that the saturation control varies between 0 and 1 depending upon the number of saturated pixels in the colour component.
12. An apparatus comprising:
a module configured to find degradation information of each colour component of a digital image captured with an imaging module comprising at least imaging optics and an image sensor, where the image is formed through the imaging optics, said image comprising at least one colour component,
a degradation function module configured to obtain a degradation function according to the degradation information,
a restoration module configured to restore said each colour component by said degradation function, wherein the restoration module is configured to restore said each colour component iteratively by iteratively applying the degradation function using an adapted step size in said iterative restoring, wherein the adapted step size is a function of a local saturation control that modulates a global step size, and
a regularization module configured to apply a regularization control to the restored colour components, wherein the regularization control limits the restoration effect near regions of the digital image containing pixels that are saturated for a colour component.
13. The apparatus according to claim 12 , further comprising means for further processing said image by other image reconstruction algorithms.
14. The apparatus according to claim 12 being capable of utilizing one of the following colour systems: RGB, HSV, OMYK.
15. The apparatus according to claim 12 , wherein the adapted step size is given by the following equation:
μ adap (m,n)=β sat (u,m)μ
where μ is the global step size of said iterative restoring, and β sat is the local saturation control that modulates the step size.
16. The apparatus according to claim 15 , wherein β sat is obtained for each colour component for the values associated with pixels of a window surrounding a given pixel location and such that the saturation control varies between 0 and 1 depending upon the number of saturated pixels in the colour component.
17. An apparatus for improving image quality comprising:
an imaging module having at least imaging optics and an image sensor, where the image is formed through the imaging optics, said image comprising at least one colour component,
a module configured to find degradation information of each colour component of a digital image captured with the imaging module',
a degradation function module configured to obtain degradation function according to the degradation information,
a restoration module configured to restore said each colour component by said degradation function, wherein the restoration module is configured to restore said each colour component iteratively by iteratively applying the degradation function using an adapted step size in said iterative restoring, wherein the adapted step size is a function of a local saturation control that modulates a global step size, and
a regularization module configured to apply a regularization control to each restored colour component, wherein the regularization control limits the restoration effect near regions of the digital image containing pixels that are saturated for a colour component.
18. A computer readable memory stored with instructions for execution by at least one processor to at least perform:
finding degradation information of each colour component of a digital image captured with an imaging module comprising at least imaging optics and an image sensor, where the image is formed through the imaging optics, said image comprising at least one colour component,
obtaining a degradation function according to the degradation information,
restoring said each colour component by said degradation function, wherein the restoring of said each colour component is performed iteratively by iteratively applying the degradation function using an adapted step size in said iterative restoring, wherein the adapted step size is a function of a local saturation control that modulates a global step size, and
applying a regularization control to each restored colour component, wherein the regularization control limits the restoration effect near regions of the digital image containing pixels that are saturated for a colour component.
19. An apparatus comprising:
means for finding degradation information of each colour component of a digital image captured with an imaging module comprising at least imaging optics and an image sensor, where the image is formed through the imaging optics, said image comprising at least one colour component,
means for obtaining a degradation function according to the degradation information,
means for restoring said each colour component by said degradation function, wherein the restoring of said each colour component is performed iteratively by iteratively applying the degradation function using an adapted step size in said iterative restoring, wherein the adapted step size is a function of a local saturation control that modulates a global step size, and
means for applying a regularization control to the restored colour components,
wherein the regularization control limits the restoration effect near regions of the digital image containing pixels that are saturated for a colour component.