System and method for image compression in X-ray imaging systems
An imaging system includes an analog-to-digital converter configured to convert an analog pixel value into a first digital pixel value. The imaging system also includes an index value source configured to receive the first digital pixel value from the analog-to-digital converter and to generate a digital index value based on a comparison of the first digital pixel value to a digital reference value. In addition, the imaging system includes a transmitter in communication with the index value source and configured to transmit the digital index value. Further, the imaging system includes an image processing component configured to receive the digital index value and to generate a second digital pixel value based at least in part on the received digital index value and a lookup table of the image processing component.
1. An imaging system, comprising:
an analog-to-digital converter configured to convert an analog pixel value into a first digital pixel value;
an index value source configured to receive the first digital pixel value from the analog-to-digital converter and to generate a digital index value based on a comparison of the first digital pixel value to a digital reference value;
a transmitter in communication with the index value source and configured to transmit the digital index value; and
an image processing component configured to receive the digital index value and to generate a second digital pixel value based at least in part on the received digital index value and a lookup table of the image processing component.
2. The imaging system of claim 1 , wherein the analog-to-digital converter is a linear analog-to-digital converter.
3. The imaging system of claim 1 , wherein the index value source comprises a comparator for comparing the first digital pixel value to the digital reference value.
4. The imaging system of claim 3 , wherein the comparator comprises a course comparator for generating a coarse digital index value and a fine comparator for generating a fine digital index value, and the image processing component is configured to generate the second digital pixel value based on the coarse and fine digital index values.
5. The imaging system of claim 1 , wherein the index value source comprises a lookup table that includes a mapping between the digital index value and the digital reference value.
6. The imaging system of claim 5 , wherein the mapping between the digital index value and the digital reference value is at least partially quadratic.
7. The imaging system of claim 5 , wherein the lookup table of the image processing component and the lookup table of the index value source are the same.
8. The imaging system of claim 5 , wherein the lookup table of the image processing component is configured to be adjusted from the lookup table of the index value source such that the mean of a quantization error is approximately zero.
9. The imaging system of claim 1 , wherein the digital index value has a bit-width smaller than a bit-width of the first and second digital pixel values.
10. The imaging system of claim 1 , comprising a detector component separate from the image processing component, wherein the detector component comprises the analog-to-digital converter, the index value source, and the transmitter.
11. A method of operating an imaging system, comprising:
converting an analog pixel value to a first digital pixel value using a linear analog-to-digital converter;
generating a digital index value based on a comparison of the first digital pixel value to a digital reference value using a digital comparator; and
mapping the generated digital index value to a second digital pixel value via an image processing component, the second digital pixel value having a larger bit-width than the digital index value.
12. The method of claim 11 , comprising transmitting the digital index value from an index value source having the digital comparator to the image processing component via a transmitter.
13. The method of claim 11 , comprising displaying an image on a display of the image processing component, wherein the image includes the second digital pixel value.
14. The method of claim 11 , wherein generating the digital index value comprises generating a coarse digital index value and a fine digital index value.
15. The method of claim 14 , wherein generating the coarse and fine digital index values comprises:
comparing a coarse digital reference value with the first digital pixel value to determine the coarse digital index value using a coarse digital comparator;
calculating a weighted difference between the determined coarse digital index value and the first digital pixel value; and
comparing a fine digital reference value with the calculated difference to determine the fine digital index value using a fine digital comparator.
16. The method of claim 11 , comprising generating the digital index value based on a lookup table mapping the digital index value to the digital reference value, and mapping the generated digital index value to the second digital pixel value using the same lookup table.
17. The method of claim 11 , comprising generating the digital index value based on a first lookup table mapping the digital index value to the digital reference value, and mapping the generated digital index value to the second digital pixel value using a second lookup table, wherein the second lookup table is adjusted from the first lookup table such that a mean quantization error is approximately zero.
18. The method of claim 11 , comprising mapping the generated digital index value to the second digital pixel value using an equation that is at least partially quadratic.