System and method to enhance the uniformity of intensity distribution on digital imaging sensors
View Patent ↗Systems, computer readable media and methods for digital processing of images captured by a sensor to enhance intensity uniformity of the images. The sensor captures an image of a white light source. Then, using the captured image, a compensation factor for each pixel of the image sensor is calculated and stored in a memory. Next, an actual image is captured by the image sensor. Subsequently, the signal intensity of each pixel is modified using the corresponding compensation factor to enhance the uniformity of the actual image.
1. A method for digital processing of an image captured by an image sensor to enhance intensity uniformity of the images, the image sensor including a plurality of pixels arranged as an array, the method comprising:
capturing a reference image of a white light source using the image sensor;
calculating a compensation factor for each of the plurality of pixels of the image sensor using the reference image, the compensation factor of a particular one of the plurality of pixels corresponding to a relationship between a reference signal intensity of a reference pixel located at a central location of the array and a measured signal intensity of the particular one of the plurality of pixels;
storing the compensation factor in a memory;
capturing an actual image using the image sensor; and
processing the captured actual image using the compensation factor to enhance intensity uniformity of the captured actual image.
2. The method of claim 1 , wherein the compensation factor is a ratio of the reference signal intensity to the measured signal intensity.
3. The method of claim 1 , wherein the step of processing the captured actual image includes:
multiplying the compensation factor to the measured signal intensity of the particular one of the plurality of pixels.
4. A computer readable medium carrying one or more sequences of instructions for digital processing of an image captured by an image sensor having a plurality of pixels arranged as an array to enhance intensity uniformity of the image, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:
capturing a reference image of a white light source using the image sensor;
calculating a compensation factor for each of the plurality of pixels of the image sensor using the reference image, the compensation factor of a particular one of the plurality of pixels corresponding to a relationship between a reference signal intensity of a reference pixel located at a central location of the array and a measured signal intensity of the particular one of the plurality of pixels;
storing the compensation factor in a memory;
capturing an actual image using the image sensor; and
processing the captured actual image using the compensation factor to enhance intensity uniformity of the captured actual image.
5. The method of claim 4 , wherein the compensation factor is a ratio of the reference signal intensity to the measured signal intensity.
6. A method for digital processing of an image captured by an image sensor having a plurality of pixels arranged as an array, the method comprising:
capturing a plurality of images of a white light source using the image sensor;
analyzing the plurality of images to create a set of compensation function for the plurality of the pixels of the image sensor, the set of compensation functions defining a relationship between a measured signal intensity of a particular one of the plurality of pixels and a reference signal intensity of a reference pixel located at a central location of the array;
storing the set of compensation functions in a memory;
capturing an actual image using the image sensor;
generating a plurality of compensation factors each of which being for an associated one of the plurality of the pixels using the set of compensation functions; and
processing the captured actual image using the plurality of compensation factors to enhance intensity uniformity of the captured actual image.
7. The method of claim 6 , wherein the step of generating the plurality of compensation factor is performed on a real time basis.
8. The method of claim 6 , wherein the compensation factor is a ratio of the reference signal intensity to the measured signal intensity.
9. A computer readable medium carrying one or more sequences of instruction for digital processing of an image captured by an image sensor having a plurality of pixels arranged as an array, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the step of:
capturing a plurality of images of a white light source using the image sensor;
analyzing the plurality of images to create a set of compensation function for the plurality of the pixels of the image sensor, the set of compensation functions defining a relationship between a measured signal intensity of a particular one of the plurality of pixels and a reference signal intensity of a reference pixel located at a central location of the array;
storing the set of compensation functions in a memory;
capturing an actual image using the image sensor;
generating a plurality of compensation factors each of which being for an associated one of the plurality of the pixels using the set of compensation functions; and
processing the captured actual image using the plurality of compensation factors to enhance intensity uniformity of the captured actual image.
10. The method of claim 9 , wherein the compensation factor is a ratio of the reference signal intensity to the measured signal intensity.
11. An image sensor device, comprising:
an array of a plurality of pixel elements each disposed at an assigned location within the array;
a memory; and
a signal intensity correction unit communicatively connected to the memory, the signal intensity correction unit having an input configured to receive an image captured by the array, the signal intensity correction unit further having an output, the signal intensity correction unit being configured to receive through the input a reference image of a white light source captured by the array, to calculate a compensation factor for each of the plurality of pixels using the received reference image, the compensation factor of a particular one of the plurality of pixels corresponding to a relationship between a reference signal intensity of a reference pixel located in a central location of the array and a measured signal intensity of the particular one of the plurality of pixels, and to store the calculated compensation factors in the memory, the signal intensity correction unit being further configured to receive through the input an actual image captured by the array, and to output a compensated image through the output, the compensated image being produced by an application of the compensation factors stored in the memory to the received actual image.
12. The method of claim 11 , wherein the compensation factor is a ratio of the reference signal intensity to the measured signal intensity.
13. The image sensor device of claim 11 , further comprising:
an analog-to-digital converter configured to receive from the array of the plurality of pixels an analog signal representing the image captured by the array, and to convert the analog signal into a digital signal representing the image captured by the array to be provided to the input of the signal sensitivity correction unit.
14. The image sensor device of claim 11 , further comprising:
a buffer memory in communication with the signal intensity correction unit, the signal intensity correction unit being configured to store the digital signal representing the actual image captured by the array in the buffer memory.
15. The image sensor device of claim 14 , wherein the compensated image is produced by multiplying the compensation factors stored in the memory to the digital signal representing the actual image stored in the buffer memory.
16. An image sensor device, comprising:
an array of a plurality of pixel elements each disposed at an assigned location within the array;
a memory; and
a signal intensity correction unit communicatively connected to the memory, the signal intensity correction unit having an input configured to receive an image captured by the array, the signal intensity correction unit further having an output, the signal intensity correction unit being configured to receive through the input a plurality of reference images of a white light source captured by the array, to analyze the plurality of reference images to create a set of compensation functions for the plurality of the pixels, and to store the set of compensation functions in the memory, the set of compensation functions defining a relationship between a measured signal intensity of a particular one of the plurality of pixels and a reference signal intensity of a reference pixel located at a central location of the array, and
wherein the signal intensity correction unit being further configured to receive through the input an actual image captured by the image sensor, to generate a compensation factor for each of the plurality of the pixels using the set of compensation functions, and to output a compensated image through the output, the compensated image being produced by an application of the compensation factors to the received actual image.
17. The method of claim 16 , wherein each of the compensation factors is a ratio of the reference signal intensity to the measured signal intensity.