Show-through measurement system and method for inks on media

• US 8,503,733 B2
• Filed: 11/16/2009
• Issued: 08/06/2013
• Est. Priority Date: 11/16/2009
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Roof, Bryan J., Bonsignore, Frank J., Crispino, Phillip S., Webster-Curley, Jacques K.
• Primary Examiner(s): Koziol, Stephen R
• Assistant Examiner(s): Lee, Jonathan S
• Application Number:
  US12/618,988
• Publication Number:
  US 20110116110A1
• Time in Patent Office: 1,359 Days
• Field of Search: None
• US Class Current: 382/112
• CPC Class Codes: H04N 1/4095 Correction of errors due to scanning a two-sided document, i.e. show-through correction

Abstract

Systems and methods of measuring an amount of show-through in a printed document are disclosed. The systems and methods include an imaging device that scans a back side of the printed document and scans a front side of the printed document with a blank document disposed thereon. The imaging device produces bitmaps related to the scans and calculates bit depths associated with the bitmaps. A difference array is calculated based on the differences between the bitmaps of the back side and front side scans, and the average value and standard deviation of the difference array is calculated. The amount of show-through of the document is measured based on a formula with the calculated average and standard deviation.

Claims

1. A method of measuring show-through of a printed document, comprising:

forming a digital image of a back side of the printed document;

forming a digital image of a front side of the printed document with a substrate disposed thereon;

determining a back side bit depth array from the back side digital image and a front side bit depth array from the front side digital image;

comparing the back side bit depth array to the front side bit depth array, wherein the comparing comprises;

calculating respective difference values between values of the back side bit depth array and a minimum value of the front side bit depth array; and

calculating a mean and a standard deviation of the respective difference values; and

determining a show-through of the printed document based on the comparing the back side bit depth array to the front side bit depth array.

2. The method of claim 1, wherein the show-through is determined by an equation:

show-through =−

log(scale_factor/(mean(differencearray)²+σ

(differencearray)²))

wherein “

mean(differencearray)” and

“

σ

(differencearray)”

refer to the mean and the standard deviation of the respective difference values, respectively, and wherein “

scale_factor”

is a number in a range of 0.1 to 100.

3. The method of claim 1, wherein the digital images of the back side and the front side of the printed document are 8-bit grayscale images.

4. The method of claim 1, further comprising:

comparing the show-through of the printed document to a show-through threshold; and

issuing a warning for the printed document if the show-through of the printed document is greater than the show-through threshold.

5. The method of claim 1, further comprising:

comparing the show-through of the printed document to a show-through threshold; and

indicating that the printed document is available for duplex printing if the show-through of the printed document is less than or equal to the show-through threshold.

6. The method of claim 1, wherein the digital images of the back side and the front side of the printed document are formed after the printed document is printed.

7. The method of claim 1, wherein the comparing the back side bit depth array to the front side bit depth array comprises:

comparing a set number of values of the back side bit depth array to a same set number of values of the front side bit depth array.

8. The method of claim 1, further comprising:

forming a difference array comprising the respective difference values; and

storing the difference array in memory.

9. The method of claim 1, further comprising:

assigning as zero a respective difference value if a value of the back side bit depth array is greater than the minimum value of the front side bit depth array.

10. The method of claim 1, further comprising:

comparing the show-through of the printed document to a show-through threshold; and

modifying a printing condition if the show-through of the printed document is greater than the show-through threshold.

11. A device for measuring show-through of a printed document, comprising:

a scanner configured to form a digital image of a back side of the printed document and form a digital image of a front side of the printed document with a substrate disposed thereon; and

a processor configured to;

determine a back side bit depth array from the back side digital image and a front side bit depth array from the front side digital image;

compare the back side bit depth array to the front side bit depth array by;

calculating respective difference values between values of the back side bit depth array and a minimum value of the front side bit depth array; and

calculating a mean and a standard deviation of the respective difference values; and

determine a show-through of the printed document based on the comparison.

12. The device of claim 11, wherein the show-through is determined by an equation:

show-through =−

log(scale_factor/(mean(differencearray)²+σ

(differencearray)²))

wherein “

mean(differencearray)” and

“

σ

(differencearray)”

refer to the mean and the standard deviation of the respective difference values, respectively, and wherein “

scale_factor”

is a number in a range of 0.1 to 100.

13. The device of claim 11, wherein the digital images of the back side and the front side of the printed document are 8-bit grayscale images.

14. The device of claim 11, wherein the processor is further configured to:

compare the show-through of the printed document to a show-through threshold; and

issue a warning for the printed document if the show-through of the printed document is greater than the show-through threshold.

15. The device of claim 11, wherein the processor is further configured to:

compare the show-through of the printed document to a show-through threshold; and

indicate that the printed document is available for duplex printing if the show-through of the printed document is less than or equal to the show-through threshold.

16. The device of claim 11, wherein the processor forms the digital images of the back side and the front side of the printed document after the printed document is printed.

17. The device of claim 11, wherein the processor, in comparing the back side bit depth array to the front side bit depth array, is further configured to:

compare a set number of values of the back side bit depth array to a same set number of values of the front side bit depth array.

18. The device of claim 11, wherein the processor is further configured to:

form a difference array comprising the respective difference values; and

store the difference array in memory.

19. The device of claim 11, wherein the processor is further configured to:

assign as zero a respective difference value if a value of the back side bit depth array is greater than the minimum value of the front side bit depth array.

20. The device of claim 11, wherein the processor is further configured to:

compare the show-through of the printed document to a show-through threshold; and

modify a printing condition if the show-through of the printed document is greater than the show-through threshold.