Apparatus, program, and method for image tone transformation, and electronic camera
AssigneeNikon Corporation
InventorKen Utagawa
Life of this patent
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Abstract
A tone transformation apparatus of the present invention extracts or generates a signal Z[i, j] according to a pixel value of a pixel [i. j] of an original image or a pixel value of its immediate neighborhood. Further, it extracts or generates a signal ZL[i, j] according to a pixel value of a neighborhood area of the pixel [i, j]. A transformation gain k for the pixel [i. j] is determined according to these signals Z, ZL. For the tone transformation, a color component or the like of the pixel [i, j] is multiplied by the transformation gain k for the pixel [i. j].
Claims15
A tone transformation apparatus transforming a tone of an original image, the apparatus comprising:
- a signal obtaining unit which extracts or generates a first signal Z[i, j] that reflects brightness, or brightness and color difference of a pixel [i, j] of the original image;
- a neighborhood processing unit which extracts or generates a second signal ZL[i, j] that reflects brightness and color difference of a neighborhood area of the pixel [i, j];
- a gain generator which generates an added composite signal Z1=(β·Z +α·ZL) of the first signal Z[i, j] and the second signal ZL[i, j], and determines a transformation gain k for the pixel [i, j] by substituting the added composite signal Z1 for Z1 in a function k=k (Z1) of a predetermined gain curve;
- and
- a tone transformation unit which performs tone transformation by multiplying, by the transformation gain k for said pixel [i, j], a color component of said pixel [i, j] or a signal component generated from the color component.
A tone transformation method of transforming a tone of an original image, the method comprising:
- extracting or generating a first signal Z[i, j] that reflects brightness, or brightness and color difference of a pixel [i, j] of the original image;
- extracting or generating the second signal ZL[i, j] that reflects brightness and color difference of a neighborhood area of the pixel [i, J];
- generating an added composite signal Z1=(β·Z+α·ZL) of the first signal Z[i, j] and the second signal ZL[i, j], and determining a transformation gain k for the pixel [i, j] by substituting the added composite signal Z1 for Z1 in a function k=k (Z1) of a predetermined gain curve;
- performing tone transformation by multiplying, by said transformation gain k for said pixel [i, j], a color component of said pixel
- [i, j] or a signal component generated from the color component;
- and
- storing or outputting the transformed tone so as to obtain a new image by applying the transformed tone to the original image, wherein a computer is used to perform the steps.
Dependencies are inferred from the claim text.