Apparatus and method for detecting enlarging ratio or reducing ratio of image data

• US 6,370,281 B1
• Filed: 12/01/1998
• Issued: 04/09/2002
• Est. Priority Date: 12/01/1997
• Status: Expired due to Term

• Current Assignee: NEC Personal Computers, Ltd. (Lenovo Group Ltd.)
• Original Assignee: NEC Corporation
• Inventors: Tanaka, Kazuyoshi
• Primary Examiner(s): Mehta, Bhavesh
• Assistant Examiner(s): Kassa, Yosef
• Application Number:
  US09/201,984
• Time in Patent Office: 1,225 Days
• Field of Search: 382/298, 382/299, 382/197, 382/295, 382/293, 382/302, 345/660, 345/670, 345/671, 348/561, 348/581
• US Class Current: 382/298
• CPC Class Codes: G06T 7/60 Analysis of geometric attributes

Abstract

An enlarging ratio or reducing ratio detecting apparatus for detecting an enlarging ratio or reducing ratio of digital image data in which the enlarging ratio or reducing ratio of an image is unknown. The apparatus has sectioning means for sectioning the digital image data into horizontal or perpendicular block sizes; conversion means for frequency-converting sectioned blocks into a two-dimension representation; addition means for adding frequencies of the blocks and obtaining a sum of the frequencies; retrieval means for retrieving frequencies at which energy is collecting using an added result; calculation means for calculating an enlarging ratio or reducing ratio based on a retrieved result; and restoration means for restoring an image from image data having the calculated enlarging ratio or reducing ratio.

Claims

1. An enlarging ratio detecting apparatus for detecting an enlarging ratio of digital image data in which said enlarging ratio of an image is unknown, comprising:

section means for sectioning said digital image data into horizontal or perpendicular block sizes;

conversion means for frequency-converting said sectioned blocks;

addition means for adding respective frequencies of said sectioned blocks;

retrieval means for retrieving frequencies at which energy is collected based on operation of said addition means;

calculation means for calculating an enlarging ratio from said retrieved frequencies; and

restoration means for restoring an image from said image data with said enlarging ratio.

2. An enlarging ratio detecting apparatus according to claim 1, wherein said conversion means includes means for applying DCT conversion to said sectioned blocks.

3. An enlarging ratio detecting apparatus according to claim 1, wherein said retrieval means can select a group of signals out of said summed frequencies which have a high energy to obtain an energy distribution.

4. An enlarging ratio detecting apparatus according to claim 1, wherein said calculation means can determine a set of frequencies from an energy distribution obtained by said retrieval means, at which energy collects, and can calculate said enlarging ratio of said image.

5. An enlarging ratio detecting apparatus according to claim 1, further including a loop circuit effective to return an output from said restoration means to said section means.

6. A reducing ratio detecting apparatus for detecting a reducing ratio of digital image data in which said reducing ratio of an image is unknown, comprising:

section means for sectioning said digital image data into horizontal or perpendicular block sizes;

conversion means for frequency-converting sectioned blocks;

addition means for adding respective frequencies of said sectioned blocks;

retrieval means for retrieving frequencies at which energy is collected based on operation of said addition means;

calculation means for calculating said reducing ratio from said retrieved frequencies; and

restoration means for restoring an image from said image data with said reducing ratio.

7. A reducing ratio detecting apparatus according to claim 6, wherein said conversion means includes means for applying DCT conversion to said sectioned blocks.

8. A reducing ratio detecting apparatus according to claim 6, wherein said retrieval means can select a group of signals out of said summed frequencies which have a high energy to obtain an energy distribution.

9. A reducing ratio detecting apparatus according to claim 6, wherein said calculation means can determine a set of frequencies from an energy distribution obtained by said retrieval means, at which energy collects, and can calculate said reducing ratio of said image.

10. A reducing ratio detecting apparatus according to claim 6, further including a loop circuit effective to return an output from said restoration means to said section means.

11. An enlarging ratio detecting apparatus for detecting an enlarging ratio of digital image data in which said enlarging ratio of an image is unknown, comprising:

section means for sectioning said digital image data into horizontal or perpendicular block sizes;

conversion means for frequency-converting said sectioned blocks using a DCT conversion;

addition means for obtaining a sum of individual frequencies of said sectioned blocks;

retrieval means for retrieving a group of said summed frequencies which have an energy above a threshold, and outputting an energy distribution of frequencies;

calculation means for determining a set of frequencies based on said energy distribution, and calculating an enlarging ratio of said image corresponding to said set; and

restoration means for restoring an image from said image data with said enlarging ratio.

12. An enlarging ratio detecting apparatus according to claim 11, further including a loop circuit effective to return an output from said restoration means to said section means.

13. A reducing ratio detecting apparatus for detecting a reducing ratio of digital image data in which said reducing ratio of an image is unknown, comprising:

section means for sectioning said digital image data into horizontal or perpendicular block sizes;

conversion means for frequency-converting said sectioned blocks using a DCT conversion;

addition means for obtaining a sum of individual frequencies of said sectioned blocks;

retrieval means for selecting a group of said summed frequencies which have an energy above a threshold, and outputting an energy distribution of frequencies;

calculation means for determining a set of frequencies based on said energy distribution and calculating said reducing ratio of said image corresponding to said set; and

restoration means for restoring an image from said image data with said reducing ratio.

14. A reducing ratio detecting apparatus according to claim 13, further including a loop circuit effective to return an output from said restoration means to said section means.

15. An image data enlarging ratio detecting method for detecting an enlarging ratio of digital image data in which said enlarging ratio of an image is unknown, said method comprising:

(a) sectioning said digital image data into horizontal or perpendicular block sizes;

(b) frequency-converting said sectioned blocks;

(c) adding individual frequencies of said sectioned blocks to obtain sums for each frequency;

(d) obtaining a set of frequencies at which energy collects in said sums for each frequency; and

(e) calculating said enlarging ratio of said image based on said set of frequencies at which energy collects.

16. An image data enlarging ratio detecting method according to claim 15, further comprising (f) restoring said image data with said calculated enlarging ratio.

17. An image data enlarging ratio detecting method according to claim 16, wherein said method applies (a) to (f) to said image data at least a second time to restore said image according to said enlarging ratio.

18. An image data enlarging ratio detecting method according to claim 15, wherein, in said step (b), frequency-conversion is DCT conversion. DCT conversion.

19. An image data reducing ratio detecting method for detecting a reducing ratio of digital image data in which said reducing ratio of an image is unknown, said method comprising:

(a) sectioning said digital image data into horizontal or perpendicular block sizes;

(b) frequency-converting said sectioned blocks;

(c) adding individual frequencies of said sectioned blocks to obtain sums for each frequency;

(d) obtaining a set of frequencies at which energy collects in said sums for each frequency; and

(e) calculating said reducing ratio of said image based on said set of frequencies at which energy collects.

20. An image data reducing ratio detecting method according to claim 19, further comprising (f) restoring said image data with said calculated reducing ratio.

21. An image data reducing ratio detecting method according to claim 20, wherein said method applies (a) to (f) to said image data at least a second time to restore said image according to said calculated reducing ratio.

22. An image data reducing ratio detecting method according to claim 19, wherein, said frequency-converting is accomplished using a DCT conversion.

23. An image ratio calculating device, comprising:

a sectioning device operative to divide image data into a plurality of blocks, each of said blocks representing a portion of an image defined by said image data;

a frequency converter operative to convert each of said blocks into a frequency representation;

a frequency adder operative to sum like frequencies extracted from each of said blocks; and

a ratio calculator operative to calculate an image ratio from said sums of like frequencies.

24. An image ratio calculating device according to claim 23, wherein:

said frequency converter obtains said frequency representation with a DCT conversion;

said ratio calculator uses sums of frequencies that contain a high energy to calculate said image ratio; and

an image restorer operates to produce said image according to an original aspect using said image ratio.

25. A method of calculating an image ratio, comprising:

dividing image data into a plurality of blocks, each of said blocks representing a portion of an image defined by said image data;

converting each of said blocks into a frequency representation;

summing like frequencies extracted from each of said blocks; and

calculating an image ratio from said sums of like frequencies.

26. A method of calculating an image ratio according to claim 25, wherein:

said blocks are converted to a frequency representation using a DCT conversion;

said image ratio calculation uses sums of frequencies that contain a high energy; and

further including restoring said image according to an original aspect using said image ratio.