Image processing apparatus, image processing method, and program product

• US 9,818,372 B2
• Filed: 12/11/2015
• Issued: 11/14/2017
• Est. Priority Date: 11/16/2011
• Status: Active Grant

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: Renesas Electronics Corporation
• Inventors: Kawaguchi, Hirofumi
• Primary Examiner(s): Sajous, Wesner
• Application Number:
  US14/966,017
• Publication Number:
  US 20160098971A1
• Time in Patent Office: 704 Days
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 5/00 Image enhancement or restoration
• CPC Class Codes: G06T 5/40 using histogram techniques
• CPC Class Codes: G06T 7/90 Determination of colour characteristics
• CPC Class Codes: G09G 2340/06 Colour space transformation
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: H04N 1/62 Retouching, i.e. modification of isolated colours only or in isolated picture areas only
• CPC Class Codes: H04N 1/628 Memory colours, e.g. skin or sky
• CPC Class Codes: H04N 9/64 Circuits for processing colour signals H04N9/77 takes precedence; camera processing pipelines for processing colour signals H04N23/84
• CPC Class Codes: H04N 9/643 Hue control means, e.g. flesh tone control

Abstract

A computer includes an image processing apparatus, the image processing apparatus includes a transformation unit that transforms color information on an input image signal on the basis of a transformation rule; a correction range calculation unit that calculates a correction range in a predetermined color space on the basis of a positional relationship between source coordinates and destination coordinates in the color space; and a point-based transfer distance calculation unit that calculates transformation destination coordinates at respective points within the correction range on the basis of the positional relationship between the source coordinates and the destination coordinates, and a positional relationship between coordinates at the respective points within the correction range and the source coordinates to reflect the calculated transformation destination coordinates on the transformation rule.

Claims

1. A computer comprising:

an image processing apparatus, said image processing apparatus comprising;

a transformation device that transforms color information on an input image signal on the basis of a transformation rule;

a correction range calculator that calculates a correction range in a predetermined color space on the basis of a positional relationship between source coordinates and destination coordinates in the color space; and

a point-based transfer distance calculator that calculates transformation destination coordinates at respective points within the correction range on the basis of the positional relationship between the source coordinates and the destination coordinates, and a positional relationship between coordinates at the respective points within the correction range and the source coordinates to reflect the calculated transformation destination coordinates on the transformation rule.

2. The computer according to claim 1,

wherein the point-based transfer distance calculator makes the transfer distance at each point smaller as a distance from the source coordinates is larger.

3. The computer according to claim 1,

wherein the correction range comprises an oval sphere in which a first line connecting the source coordinates and the destination coordinates is parallel to a long-axis direction.

4. The computer according to claim 3, wherein the correction range calculator includes:

a first distance calculator that calculates a distance between the source coordinates and the destination coordinates;

a line inclination calculator that calculates an inclination of the first line;

a correction range adjustment device that calculates the coordinate range on the basis of a predetermined adjustment value and the distance calculated by the first distance calculator;

a rotation angle calculator that calculates a rotation angle by which the coordinate range is rotated, on the basis of the inclination of the first line which is calculated by the line inclination calculator; and

a correction range oval sphere expression calculator that calculates the oval sphere by rotating the coordinate range calculated by the correction range adjustment device by the rotation angle.

5. The computer according to claim 4,

wherein the correction range calculator calculates an inclination Δ

1 of a first cross-section and an inclination Δ

2 of a second cross-section of the first line in the color space by the following expressions (Ex.

     36) and (Ex.

     37) when it is assumed that the source coordinates are O(Ro, Go, Bo), and the destination coordinates are T(Rt, Gt, Bt) in the color space

6. The computer according to claim 5,

wherein the rotation angle calculator calculates the rotation angle Δ

1 on the first cross-section and the rotation angle Δ

2 on the second cross-section in the color space by the following expressions (Ex.

     38) and (Ex,

     39)

7. The computer according to claim 3,

wherein the point-based transfer distance calculator includes:

a linear expression calculator that calculates a linear expression of a second line connecting a first coordinate point included in the correction range and the source coordinates;

an intersection point calculator that calculates an intersection point between the oval sphere and the second line on the basis of a mathematical expression of the oval sphere and the linear expression of the second line;

a second distance calculator that calculates a distance between the source coordinates and the intersection point;

a third distance calculator that calculates a distance between the first coordinate point and the source coordinates;

an influence degree calculator that calculates the degree of influence which is the basis of the transfer distance of the first coordinate point according to a ratio of the distance calculated by the second distance calculator and the distance calculated by the third distance calculator; and

a coordinate calculator that calculates the transformation destination coordinates of the first coordinate point on the basis of the degree of influence.

8. The computer according to claim 7,

wherein the coordinate calculator calculates the transformation destination coordinates of the first coordinate point according to a correction direction including one of a compression direction and a parallel direction designated by the user.

9. The computer according to claim 8,

wherein the point-based transfer distance calculator includes a transfer characteristic adjustment device that calculates transfer characteristics adjusted to be increased more than a linear change, and sets the transfer characteristics as a parameter when the coordinate calculator calculates the transformation destination coordinates of the first coordinate point.

10. The computer according to claim 1,

wherein the coordinates of each point within the correction range to be processed by the point-based transfer distance calculator comprise lattice point coordinates in which all of distances from adjacent points are equal to each other.

11. The computer according to claim 1,

wherein the source coordinates and the destination coordinates comprise input values designated by the user.

12. The computer according to claim 1, further comprising a picture adaptation device that receives, from the user, a type of a memory color correction target, a first preset value of the source coordinates, and a second preset value of the destination coordinates related to each memory color correction target to be corrected, determines whether the memory color correction target designated by the user exists within an image configured by the image signal, or not, analyzes a color distribution of the image, adjusts at least one of the first preset value and the second preset value for each of the correction targets that exist within the image on the basis of analysis results of the color distribution in the image, and sets adjusted values to the source coordinates and the destination coordinates for each of the memory color correction targets.

13. The computer according to claim 12,

wherein the picture adaptation device includes:

a correction target detection device that detects the presence or absence of an object or a background to be subjected to the memory color correction within the image, and a detection area of the memory color correction target within the image;

a memory color correction determination device that compares a detection result of the correction target detection device with the type of the memory color correction target designated by the user to determine the memory color correction target to be conducted;

a histogram generation device that generates a color space histogram of the image;

a histogram analysis device that calculates a first analysis result related to a color distribution analysis within the detection area, and a second analysis result related to a color distribution analysis between the color space coordinates indicated by the first preset value and the second preset value, on the basis of the color space histogram; and

a source and destination calculator that calculates the source coordinates and the destination coordinates for each of the memory color correction targets which exist within the image, on the basis of the memory color correction target determined by the memory color correction determination device, the first and second analysis results, and the first and second preset values,

wherein the transformation device includes at least a first transformation device and a second transformation device,

wherein the picture adaptation device detects the respective display areas of the first color correction target and the second memory color correction target, which are the memory color correction targets designated by the user, within the image,

wherein the correction range calculator calculates the respective correction ranges corresponding to the first and second memory color correction targets, and

wherein the point-based transfer distance calculator calculates the transformation destination coordinates of the respective points within the correction range of the first memory color correction target to reflect the calculated transformation destination coordinates on the transformation rule of the first transformation device, and calculates the transformation destination coordinates of the respective points within the correction range of the second memory color correction target to reflect the calculated transformation destination coordinates on the transformation rule of the second transformation device.

14. The computer according to claim 13,

wherein the histogram analysis device sets main color coordinates indicative of a main color in the detection area as the first analysis result, divides an area between the color space coordinates indicated by the first preset value and the second preset value into a plurality of areas, determines whether a given number of pixels or more exist in the respective areas, or not, in order from an area closer to the first preset value, and sets the existence coordinates which are representative coordinates of the areas in which the given number of pixels or more exist as the second analysis result.

15. The computer according to claim 14,

wherein the source and destination calculator calculates the source coordinates and the destination coordinates by the following expressions (Ex. 40) and (Ex. 41) assuming that the main color coordinates are OC(OCr, OCg, OCb), the existence coordinates are TE(TEr, TEg, TEb), the first preset value is OP(OPr, OPg, ORb), the second preset value is TP(TPr, TPg, TRb), the source coordinates are O(Ro, Go, Bo), the destination coordinates are T(Rt, Gt, Bt), and following degrees adjustable by the user are F1 (0˜

100%) and F2 (0˜

400%)

Ro=OPr+(OCr−

OPr)×

F1

Go=OPg+(OCg−

OPg)×

F1

Bo=OPb+(OCb−

OPb)×

F1 

 

(Ex.

     40)

Rt=TPr+(TEr−

TPr)×

F2

Gt=TPg+(TEg−

TEg)×

F2

Rt=TPr+(TEb−

TPb)×

F2 

 

(Ex.

     41).

16. The computer according to claim 1,

wherein the correction range calculator receives an input of a rule limit number of the transformation rule from the user, compares the number of respective point coordinates within the correction range which is calculated from a size of the correction range with the rule limit number, and recalculates the correction range so that the area range becomes smaller if the rule limit number is smaller than the number of respective dot coordinates within the correction range,

wherein the correction range calculator recalculates the correction ranges after at least one of the source coordinates and the destination coordinates is so adjusted as to decrease a distance between the source coordinates and the destination coordinates.

17. The computer according to claim 1,

wherein the correction range calculator receives an input of a priority order of the memory color correction targets from the user, determines whether the correction ranges of the respective memory color correction targets overlap with each other, and recalculates the correction ranges of the respective memory color correction targets so that a reduction ratio of the correction ranges of the memory color correction targets becomes larger in ascending order of the priority order, and

wherein the color space comprises any one of RGB, HSV, HSU, YUV, HLS, Lab, and YCM.

18. The computer according to claim 1,

wherein the transformation rule comprises information in an LUT (lookup table).

19. The computer according to claim 1, wherein the transformation device, the correction range calculator, and the point-based transfer distance calculator are each configured by hardware as a circuit.

20. The computer according to claim 1, wherein the transformation device, the correction range calculator, and the point-based transfer distance calculator are each configured as a program supplied to the computer.