JPS63119384A - Picture correction system - Google Patents

Abstract

PURPOSE:To prevent defect of color reproducibility at a high contrast part by correcting a density data of each color based on a density correction data generated corresponding to an exposure characteristic of each color of a color film and correcting a picture based on the corrected density data. CONSTITUTION:The picture density of each photosensitive layer of blue, red and green colors of a photosensitive film 10 is inputted by a picture density input section 11. A correction section 13 uses a characteristic curve of the green photosensitive layer as a referenced characteristic curve to correct the picture of the blue and red photosensitive layer. A correction table 14 used by the correction section 13 is formed in advance corresponding to the kinds of each film. The data corrected in this way is used and the picture is corrected by a correction section 15 to prevent the reproduction of uncorrect color.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an image correction method for restoring a well-corrected image with less pre-image from a pre-image recorded on a color film, for example.

[Prior Art] In the conventional pre-image correction methods, there are few methods for color images, and most of them are for black and white images. Therefore, when correcting a pre-image recorded on a color film, first read the image data of each of the blue, green, and red photosensitive layers recorded on the film in the same way as a monochrome image, and then Digital processing was performed to correct the image, and the corrected images were combined again as a blue image, a green image, and a red image to obtain a color corrected image.

[Problems to be Solved by the Invention] However, with such conventional methods, colors different from the original colors are reproduced in high contrast areas of the corrected image, resulting in insufficient color reproduction performance. there were.

The present invention has been made in view of the above-mentioned conventional example, and an object of the present invention is to provide an image correction method that can prevent defects in color reproducibility in high-contrast areas and perform high-performance image correction.

[Means for Solving the Problems] In order to achieve the above object, the image correction method of the present invention includes the following proofreading. That is, a manual means for inputting an image recorded on a color film for each color and converting it into density data, a means for creating density correction data corresponding to the exposure characteristics of each color of the color film, and a means for converting the density correction data into density data. The image forming apparatus basically includes a correction means for correcting the density data for each color, and a correction means for correcting the image based on the corrected density data.

[Operations] In the above configuration, images recorded on color film are input for each color and converted into density data. It operates to correct the density data of each color based on the density correction data created corresponding to the exposure characteristics of each color of the color film, and to correct the image based on the density data corrected by the correction means. .

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

When the optical densities of the blue image, recorded image, and red image recorded on reversal film are read and converted into digital data, the characteristic curves showing the density relative to the exposure amount of each photosensitive layer do not match depending on the film. Even if such data is processed and combined again, correct subject data may not be obtained.

FIG. 2 is a diagram showing the density characteristics of each photosensitive layer of Kodak's Kodachrome 64 (daylight type film) with respect to the exposure amount.

20 is a red (R) photosensitive layer, 21 is a green (G) photosensitive layer, 2
2 is a curve showing the density characteristics of the blue (B) photosensitive layer with respect to the exposure amount.

FIG. 3 is a diagram showing a case where a film in which the R, G, and B photosensitive layers have different characteristics is exposed to a neutral gray subject light amount distribution shown in 30.

31 to 33 show the density distribution in each photosensitive layer after the subject light amount distribution 30 is recorded on the blue, green, and red photosensitive layers, respectively, and development processing is performed. Therefore, even if the density distribution of the photosensitive layer for the three colors recorded on this film is correctly read, digitized, and reproduced, data corresponding to the subject light amount distribution 3o will not be obtained.

If the recorded image becomes blurry and degraded due to camera shake while photographing a subject, the contrast of high-contrast parts of the image will decrease slightly due to the blur. However, in the recorded image, differences in density distribution occur due to differences in the characteristic curves of the photosensitive layers, as shown at least in FIG.

Generally, when correcting blurred images, processing is performed to amplify the contrast of high spatial frequency components degraded by blurring, so the difference in density distribution on the film described above is amplified. Color shift will be noticeable in the image.

Therefore, in this embodiment, after reading three images of blue, green, and red from a color film as digital data, a process is performed to correct the difference in the characteristic curves of the respective photosensitive layers.

The processing will be explained below.

FIG. 1 is a functional block diagram showing this embodiment.

Reference numeral 10 denotes a photosensitive film having, for example, the characteristics shown in FIG.
Input the image density of each blue and green photosensitive layer. Reference numeral 12 denotes an A/D converter that inputs analog density data from the image density input unit 11 and converts it into a digital signal. Reference numeral 13 denotes a correction section which uses the characteristic curve of the green photosensitive layer shown in FIG. 2 as a reference characteristic curve and corrects the images of the blue and red photosensitive layers.

14 is a correction table used by the correction section 13. Creation of correction data for this correction table 14 will be explained below. In the characteristic curve of FIG. 2, a certain exposure fl E O
The optical densities of blue, green, and red for
o), D a (E o), and D R (E Q).

Thus, Da(Eo) −Da for D[1(EO)
(E o)D a(E o) for DR(EO)
If -D R (E O) is plotted while changing EO, the corrected density curve shown in FIG. 4 is obtained. Based on this correction density curve, a correction table is created in advance for each type of film.

In Figure 4, 40 beams. (E O) -D B(E
Blue correction curve obtained in O), beam 41. (E
o) It is a red correction curve determined by -DR(EO).

Let the density value of the blue image be da (X, y) and the density value of the red image dr (x, y) (x, y are variables indicating the position within the image), and the data in the correction table 14 for that film should be CB% for the layer, CR for the red photosensitive layer, the density value corrected by the correction unit 13 is da(x,y)+Ca(dllll(x,Y))d,(x
, y)+CR(d, (X, Y)) is obtained.

By correcting the image in the correction section 15 using data corrected in this manner, it is possible to prevent incorrect color reproduction. This image modification includes pre-image modification, restoration of a blurred image, restoration of a degraded image formed due to low MTF (modulation transfer function) characteristics, and the like.

In this embodiment, the characteristic curve of the green photosensitive layer was used as the reference characteristic curve, but any reference characteristic curve can be selected. However, if one of the characteristic curves of the blue, green, and red photosensitive layers is used as the reference characteristic curve, there is an effect that the number of correction table data can be reduced by one.

In addition, as a color film, positive color film (
It is not limited to reversal color films, but is equally effective for negative color films.

As described above, according to this embodiment, image correction with good color reproduction performance can be realized.

[Effects of the Invention] As described above, according to the present invention, defects caused by differences in exposure characteristics can be corrected, and an image correction method with good color reproduction can be provided.

[Brief explanation of the drawing]

Figure 1 is a functional block diagram of this embodiment. Figure 2 is a diagram showing the characteristic curve of color positive film. Figure 3 is a schematic diagram showing the difference in recording characteristics in high contrast areas. FIG. 3 is a diagram showing an example of a corrected density curve. In the figure, 10... Photosensitive film, 11... Image density manual section, 12... A/D conversion section, 13... Correction section, 1
4... Correction table, 15... Correction section, 20...
Characteristic curve of red photosensitive layer, 21... Characteristic curve of green photosensitive layer, 22... Characteristic curve of blue photosensitive layer, 40... Blue correction curve, 41... Red correction curve. Patent applicant: Canon Co., Ltd. Figure 1 tT kneet (Joshin: Tokui Ru..., Kusu Tobu) Figure 2

Claims (1)

[Claims] an input means for inputting an image recorded on a color film for each color and converting it into density data; a means for creating density correction data corresponding to the exposure characteristics of each color of the color film; and a means for creating density correction data based on the density correction data. An image correction method comprising: a correction means for correcting the density data for each color; and a correction means for correcting the image based on the corrected density data.