Color correction apparatus

Abstract

An object is to carry out color correction in a highly accurate manner on images acquired by various digital cameras and scanners. A color correction apparatus includes a determining unit configured to determine whether or not preprocessing for removing the effect of previously-performed color correction is required for a reference image that is used for a reference of color correction and a color correction target image on which color correction is to be carried out; a preprocessing unit configured to carry out preprocessing on a reference image and a color correction target image that is determined by the determining unit as requiring preprocessing and output a preprocessed image; a color-correction processing unit configured to acquire a reference image or color correction target image that is not preprocessed if the determining unit determines that the reference image or color correction target image does not require preprocessing or to acquire a preprocessed reference image or color correction target image if the determining unit determines that the reference image or color correction target image requires preprocessing, and to correct the color correction target image on the basis of the acquired reference image.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram of the overall structure of a color correction apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of the overall structure of a preprocessing unit illustrated in FIG. 1.

FIG. 3 is a block diagram of the overall structure of a color-correction processing unit illustrated in FIG. 1.

FIG. 4 illustrates an example of an image to be color-corrected.

FIG. 5 illustrates an example reference image.

FIG. 6 illustrates a γ-correction characteristic.

FIG. 7 illustrates an S-curve characteristic used for gradation correction.

FIG. 8 illustrates the overall structure of a multi-spectral camera and a cradle according to an embodiment of the present invention.

FIG. 9 illustrates the spectrum of a light source illustrated in FIG. 8.

FIG. 10 is a flow chart illustrating an example process executed by software so as to carry out a color correction method in a color correction apparatus according to an embodiment of the present invention.

Claims

1. A color correction apparatus comprising: a determining unit configured to determine whether or not preprocessing for removing the effect of previously-performed color adjustment is required for a reference image that is used for a reference of color adjustment and a color correction target image on which color correction is to be carried out;a preprocessing unit configured to carry out preprocessing on the reference image and color correction target image that are determined by the determining unit as requiring preprocessing and to output preprocessed images; anda color-correction processing unit configured to acquire a reference image or color correction target image that is not preprocessed if the determining unit determines that the reference image or color correction target image does not require preprocessing or to acquire a preprocessed reference image or color correction target image if the determining unit determines that the reference image or color correction target image requires preprocessing, and to correct the color correction target image on the basis of the acquired reference image.

2. The color correction apparatus according to claim 1, wherein the preprocessing includes gradation restoration for restoring the effect of gradation correction that has been previously performed on an input reference image or color correction target image.

3. The color correction apparatus according to claim 1, wherein the preprocessing includes γ-correction for restoring the effect of inverse γ-correction that has been previously performed on an input reference image or color correction target image.

4. The color correction apparatus according to claim 1, further comprising: an input unit configured to receive an input from an external unit concerning whether or not the preprocessing is required,wherein the determining unit carries out a determination process on the basis of information received from the input unit.

5. The color correction apparatus according to claim 1, wherein the determining unit carries out a determination process on the basis of at least one of a file name and attribute information of the reference image and color correction target image.

6. The color correction apparatus according to claim 1, wherein the reference image comprises spectral image data corresponding to more than four spectral bands.

7. The color correction apparatus according to claim 1, wherein the preprocessing unit includes an estimating unit configured to estimate the type of the input apparatus used for inputting the reference image or the color correction target image,a storage unit configured to store, in association with the input apparatus, parameters used for the preprocessinga parameter-acquiring unit configured to acquire parameters corresponding to the input apparatus estimated by the estimating unit, anda processing unit configured to carry out the preprocessing on the input reference image or color correction target image using the parameters acquired by the parameter-acquiring unit.

8. The color correction apparatus according to claim 1, further comprising: a reference-image storage unit configured to store a plurality of reference images;a reference-image selecting unit configured to select a reference image that satisfies a predetermined condition from the reference-image storage unit; anda reference-image acquiring unit configured to acquire a reference image selected by the reference-image selecting unit from the reference-image storage unit,wherein the color-correction processing unit corrects the color correction target image using a reference image acquired by the reference-image acquiring unit.

9. The color correction apparatus according to claim 8, wherein the reference-image storage unit is provided on a file server connected via a network.

10. The color correction apparatus according to claim 8, further comprising: a color-correction-target-image analyzing unit configured to analyze the color correction target image,wherein the reference-image selecting unit selects a reference image in accordance with the analysis result of the color-correction-target-image analyzing unit.

11. The color correction apparatus according to claim 8, further comprising: an image-acquisition information input unit configured to input information related to at least one of an object and an image-acquisition condition of the color correction target image,wherein the reference-image selecting unit selects a reference image in accordance with the information input from the image-acquisition information input unit.

12. The color correction apparatus according to claim 8, further comprising: a candidate-presenting unit configured to present a plurality of reference images selected by the reference-image selecting unit to the user as reference image candidates; anda reference-image determining unit configured to select a reference image to be actually used from the reference image candidates presented by the candidate-presenting unit,wherein the plurality of reference images is selected by the reference-image selecting unit as reference images.

13. A method of color correction comprising: a determining step of determining whether or not preprocessing for removing the effect of previously-performed color adjustment is required for a reference image that is used as a reference of color adjustment and a color correction target image on which color correction is to be carried out;a preprocessing step of carrying out preprocessing on the reference image and color correction target image that are determined as requiring preprocessing and outputting preprocessed images; anda color correction step of acquiring a reference image or color correction target image that is not preprocessed if the determining unit determines that the reference image or color correction target image does not require preprocessing or acquiring a preprocessed reference image or color correction target image if the determining unit determines that the reference image or color correction target image requires preprocessing, and correcting the color correction target image on the basis of the acquired reference image.

14. The method of color correction according to claim 13, further comprising: a reference-image storing step of storing a plurality of reference images;a reference-image selecting step of selecting a reference image that satisfies a predetermined condition from the plurality of reference images stored in the reference-image storing step; anda reference-image acquiring step of acquiring the selected reference image,wherein, in the color correction step, the color correction target image is corrected using the reference image acquired in the reference-image acquiring step, andwherein, in the reference-image acquiring step, the reference image is acquired via a network.

15. A color correction program to be executed by a computer, the program comprising: a determining step of determining whether or not preprocessing for removing the effect of previously-performed color adjustment is required for a reference image that is used as a reference of color adjustment and a color correction target image on which color correction is to be carried out;a preprocessing step of carrying out preprocessing on the reference image and color correction target image that are determined as requiring preprocessing and outputting preprocessed images; anda color correction step of acquiring a reference image or color correction target image that is not preprocessed if the determining unit determines that the reference image or color correction target image does not require preprocessing or acquiring a preprocessed reference image or color correction target image if the determining unit determines that the reference image or color correction target image requires preprocessing, and correcting the color correction target image on the basis of the acquired reference image.

16. The color correction program according to claim 15, further comprising: a reference-image storing step of storing a plurality of reference images;a reference-image selecting step of selecting a reference image that satisfies a predetermined condition from the plurality of reference images stored in the reference-image storing step; anda reference-image acquiring step of acquiring the selected reference image,wherein, in the color correction step, the color correction target image is corrected using the reference image acquired in the reference-image acquiring step, andwherein, in the reference-image acquiring step, the reference image is acquired via a network.