JPS63119385A - Picture correction system - Google Patents

Abstract

PURPOSE:To prevent defect of color reproducibility due to the difference from the film characteristic by converting a density data into the exposure quantity corresponding to the exposure characteristic of each color of a color film and correcting the picture based on the exposure. CONSTITUTION:The picture density of each photosensing layer of red, blue and green colors of a photosensitive film 10 is inputted by a picture density input section 11. An exposure conversion section 13 converts the density data into the exposure data based on the characteristic curve data 14 of the film. The picture read based on the exposure is expressed as the exposure in place of the density data as the picture data and the correction section 15 aplies correction processing to the picture data. In applying the picture correction in this way, the reproduction of erroneous color due to the difference of characteristic of each color specific to each film is prevented.

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 due to differences in film characteristics and can 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, an input means for inputting an image recorded on a color film for each color and converting it into density data, and a conversion means for converting the density data into an exposure amount based on the exposure characteristics of each color of the color film. and a correction means for correcting the image based on the exposure amount.

[Operation] In the above configuration, an image recorded on a color film is input for each color and converted into density data. The density data is converted into an exposure amount in accordance with the exposure characteristics of each color of the color film, and the correction means operates to correct the image based on the exposure amount.

[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 the neutral gray subject light amount distribution shown in 3o.

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 mentioned above is amplified. Color shift will be noticeable in the image.

Therefore, in this example, the color film is The read density data is converted from density data to exposure data using the characteristic curves of the three color photosensitive layers of this film, and using this exposure data (the shutter speed at the time of photography is is constant, so this corresponds to the illuminance distribution of the subject),
Perform the following image correction processing.

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. 13, as shown in FIG. 4, is an exposure amount conversion section that converts density data into exposure amount data based on film characteristic curve data 14.

That is, the characteristic curve data of a color film is tabulated and stored in a computer. For example, when the optical density of a film image is 2.0, as shown in Figure 4, if it is a blue image, Determine the exposure amount EB from the characteristic curve, and if it is a recorded image, set it to E. , if it is a red image, calculate the ER. Based on these exposure amounts, image data is created by arranging the read image with the exposure amount instead of the density data, and correction processing is performed on this image data.

Reference numeral 14 indicates film characteristic data used by the exposure amount converter 13. The method for storing this film characteristic data is as follows: (1) The characteristic curve is divided into a number of straight lines, each straight line portion is stored as a function representing the straight line, and the density is converted into exposure amount according to the function.

(2) The characteristic curve is approximated by polynomial approximation, and this polynomial is used to convert density to exposure amount.

(2) Since the density data of a normal image is n bits (n is a positive integer), the density measurement range is resolved using this resolution, and the corresponding exposure amount data is read from the graph and converted into numerical values.

Possible methods include:

In this way, by converting the density data of the three color photosensitive layers on the film image into exposure amounts and performing image correction on this exposure data, it is possible to eliminate incorrect colors due to differences in the characteristics of each color unique to the film. Reproduction can be prevented. 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 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 peculiar to films 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. Figure 4 is a diagram showing the characteristics. It is a diagram showing an example of conversion from density data to exposure data based on a curve.In the figure, 10...Photosensitive film, 11...Image density manual section, 12...A/D conversion section , 13... Exposure amount conversion unit, 14... Film characteristic data, 15... Correction unit, 20... Characteristic curve of red photosensitive layer, 21... Characteristic curve of green photosensitive layer, 22...・Characteristic curve of blue photosensitive layer. Patent applicant Canon Co., Ltd. Figure 2 Figure 1 Figure 3

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 conversion means for converting the density data into an exposure amount based on the exposure characteristics of each color of the color film; An image correction method comprising: a correction means for correcting the image based on the exposure amount.