Gamma curve generation method and device for the same
View Patent ↗The gamma curve generation method of the invention selects each set of three consecutive control points among multiple consecutive control points, forms a cubic curve passing through the selected three consecutive control points, and combines all formed cubic curves to generate a gamma curve. The selected three consecutive control points are set to a first control point, a second control point, and a third control point in a sequential order. Each cubic curve is formed to pass through the first control point, the second control point, and the third control point and have a tangent of a certain gradient at the second control point, which is internal division at an inverse ratio of a gradient of a straight line connecting the first control point with the second control point and a gradient of a straight line connecting the second control point with the third control point. This arrangement of the invention demands the less amount of computation and desirably reduces the required circuit scale.
1. A gamma curve generation method of generating a curve passing through multiple consecutive control points as a gamma curve used for gamma correction of an image signal, the gamma curve generation method comprising the steps of:
(a) selecting each set of three consecutive control points among the multiple consecutive control points;
(b) forming a cubic curve passing through the selected three consecutive control points; and
(c) combining all cubic curves formed in the step (b) to generate the gamma curve,
the step (b) setting the selected three consecutive control points to a first control point, a second control point, and a third control point in a sequential order and specifying the cubic curve that passes through the first control point, the second control point, and the third control point and has a tangent of a gradient G at the second control point, which satisfies Equation (1) given below:
G
=
G
12
×
G
23
+
G
23
×
G
12
G
12
+
G
23
(
1
)
where G 12 denotes a gradient of a straight line connecting the first control point with the second control point and G 23 denotes a gradient of a straight line connecting the second control point with the third control point,
wherein the above steps are performed by a processor.
2. A gamma curve generation method of generating a curve passing through multiple consecutive control points as a gamma curve used for gamma correction of an image signal, the gamma curve generation method comprising the steps of:
(a) selecting each set of three consecutive control points among the multiple consecutive control points;
(b) forming a cubic curve passing through the selected three consecutive control points; and
(c) combining all cubic curves formed in the step (b) to generate the gamma curve,
the step (b) setting the selected three consecutive control points to a first control point, a second control point, and a third control point in a sequential order and specifying the cubic curve of passing through the first control point, the second control point, and the third control point to minimize a sum of an area defined by a straight line and an arc of the cubic curve between the first control point and the second control point and an area defined by a straight line and an arc of the cubic curve between the second control point and the third control point,
wherein the above steps are performed by a processor.
3. A gamma curve generation device that generates a curve passing through multiple consecutive control points as a gamma curve used for gamma correction of an image signal,
the gamma curve generation device selecting each set of three consecutive control points among the multiple consecutive control points, forming a cubic curve passing through the selected three consecutive control points, and combining all formed cubic curves to generate the gamma curve,
the gamma curve generation device setting the selected three consecutive control points to a first control point, a second control point, and a third control point in a sequential order and specifying the cubic curve that passes through the first control point, the second control point, and the third control point and has a tangent of a gradient G at the second control point, which satisfies Equation (1) given below:
G
=
G
12
×
G
23
+
G
23
×
G
12
G
12
+
G
23
(
1
)
where G 12 denotes a gradient of a straight line connecting the first control point with the second control point and G 23 denotes a gradient of a straight line connecting the second control point with the third control point.
4. A gamma curve generation device that generates a curve passing through multiple consecutive control points as a gamma curve used for gamma correction of an image signal,
the gamma curve generation device selecting each set of three consecutive control points among the multiple consecutive control points, forming a cubic curve passing through the selected three consecutive control points, and combining all formed cubic curves to generate the gamma curve,
the gamma curve generation device setting the selected three consecutive control points to a first control point, a second control point, and a third control point in a sequential order and specifying the cubic curve that passes through the first control point, the second control point, and the third control point to minimize a sum of an area defined by a straight line and an arc of the cubic curve between the first control point and the second control point and an area defined by a straight line and an arc of the cubic curve between the second control point and the third control point.