JP2502823B2 - Reproduction of photographic originals with scatter correction - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates generally to reproduction of original drawings.

More particularly, the invention relates to a method and apparatus for scanning an original image at multiple points to generate a signal representing the image of the original image. The individual signals are processed to enhance the image quality, and the image is then printed point by point.

[0003]

2. Description of the Related Art For example, European Patent No. 1
Electronic image processing, as disclosed in US Pat. No. 23,701, is increasingly being used in the reproduction of positive and negative color originals. The original is first electro-optically scanned along rows and columns, i.e. point by point, to produce a signal representing the image of the original. These image signals are modified according to predetermined criteria. As a rule, the image signal is digitized,
It is then temporarily stored in digital memory. The image signal is converted to an optical image using a printer that includes a cathode ray tube that prints the image on paper. Printing is achieved by continuously exposing the paper with light of the three primary colors.

Both the point-by-point scanning of the original and the printing of the image are carried out via an objective lens and suitable color filters. Since the light used for scanning and printing passes through these glass bodies, some amount of scattering is inevitably generated. The objective lens used for scanning focuses the light onto a sensor that produces an image signal, and the scattered light is
Increasing the intensity of dark areas of the image at the sensor above the desired intensity. Similarly, scattered light causes the light intensity in the bright areas of the image on the photographic paper to increase above the desired light intensity. Thus
Scattered light tends to alter the image. Scattered light has a particularly detrimental effect when illuminating parts of the image that require low light intensity, as it greatly affects the brightness of the image.

Providing a method for improving image quality includes:
It is the purpose of the invention.

Another object of the present invention is to provide a method which makes it possible to at least partially correct the effects of scattered radiation.

An additional object of the invention is to provide a method of reducing or eliminating the effects of scattered radiation in the final image.

Yet another object of the present invention is to provide a device for improving the quality of an image. It is also an object of the invention to provide a device that is able to at least partially correct the effects of scattered radiation.

A further object of the invention is to provide a device which makes it possible to reduce or eliminate the effects of scattered radiation in the final image.

The above objects, as well as others that will become apparent as the description proceeds, are accomplished by the present invention.

[0011]

According to one aspect of the present invention,
There is a method of copying the original drawing. The method includes scanning the original at multiple points to establish the intensity of the original, and generating a value representing the intensity. At least one characteristic value is generated for each point and represents the intensity of each point. The characteristic value is, for example, proportional to the brightness of each point. The method further comprises the steps of establishing a mean value representing the mean brightness of the original, and using the mean value to calculate a scatter correction. The method further comprises correcting each of the characteristic values using the correction, and replicating the original image based on the corrected characteristic values.

The correction is preferably constant for all originals. The correction step involves subtracting the correction from each of the characteristic values.

The scattering step directs radiation onto the original figure,
Passing the radiation through at least one optical element that causes scattering of the radiation. The correction then at least partially compensates for the scattering of the radiation by the optical element. The light elements used during scanning to cause scattering include objectives and color filters. The latter is usually used for color originals.

The generating step includes deriving an original characteristic value for each point during the scattering step and processing each of the original characteristic values. The original characteristic values are all in order to express the image of the original drawing,
The operation of processing the individual original characteristic values corresponds to the processing of each point of the image. The correction step is performed using the original characteristic value and / or the processing characteristic value.

If the original is color, the original is generally scanned in each of the three primary colors red, green and blue. Then, the steps of generating a characteristic value, establishing an average value representing the average luminance, calculating a scatter correction, and correcting the characteristic value are performed for each primary color. .

The scanning step for a color original consists of directing the radiation at the original, continuously filtering the radiation in the three primary colors red, green and blue when the radiation is transmitted from the original, and by means of multiple radiation sensing elements. Detecting the filtered radiation. The radiation sensing element is, for example,
It constitutes a part of the charge coupled device. The generating step involves converting the filtered radiation that reaches the radiation sensing element into an output signal that represents the original characteristic values of each of the various points of the original diagram.

The calculation step is performed using the following equation:

[0018]

## EQU00001 ## U (i) = k (i) .times.U (i) where U (i) is a voltage representing the average luminance of the original image in one of the three primary colors red, green or blue, and k (i) (I)
Is a constant for each primary color and specific optical system,
U (i) is a voltage expressing the correction of each primary color.

The duplication step involves printing the image of the original figure point by point. Such printing is accomplished by irradiating a radiation-sensitive material with a radiation beam, adjusting the intensity of the beam point by point, and passing the beam through at least one optical element that causes scattering of the beam. Here again, the correction at least partially compensates for the scattering of the beam by the light element and, in particular, at least partially for the effects of scattered radiation from the beam due to the exposure of the radiation-sensitive material. As before, the light elements used for printing to cause scattering include objectives and color filters. A cathode ray tube is used to generate the printing beam, and the screen of the cathode ray tube is also responsible for the scattering of the beam. The intensity of the beam is adjusted based on the characteristic values generated for each point in the original.

Another aspect of the invention is an apparatus for reproducing an original drawing. The device scans the original at multiple points,
And means for generating a value representing the luminance of the original image. These values include at least one characteristic value for each point that represents the brightness of the respective point. The device is
Furthermore, an averaging means functionally associated with the scanning and generating means and arranged to establish an average value representing the average brightness of the original, and an averaging means functionally established with the averaging means. A calculation means arranged to calculate a scatter correction from an average value generated by the characteristic value using the correction functionally related to the scanning and generating means and the calculation means and calculated by the calculation means And a duplicating means functionally associated with the compensating means and arranged to duplicate the original drawing based on the compensated characteristic values. The device according to the invention comprises:
It is used to carry out the method of the invention.

The scanning and generating means supports the radiation source, means for directing radiation from the source along a predetermined path in a predetermined direction, and the original at a preselected position in the path downstream of the radiation source. And means for. The scanning and generating means further detect means for diverting a portion of the radiation from the path at another location downstream of the pre-selected location, and detect the diverted radiation and represent the full intensity of the original. Means for issuing various values. The detection and issuing means are
It is arranged to transmit the issued value to the averaging means.

The scanning and generating means also comprises sensing means at additional locations in the path downstream of where radiation is diverted from the path. The sensing means are designed to form an image of the original, and the directing means include an objective lens for focusing the non-detoured portion of the radiation on the sensing means.

The scanning and generating means include means for generating characteristic values for each point of the original in each of the primary colors red, green and blue. The detecting and issuing means forming part of the scanning and generating means comprise respective detecting and issuing devices for each of the primary colors, eg respective optoelectronic devices. The averaging means includes means for establishing an average value for each primary color, and the calculating means includes a multiplication unit for multiplying each average value by a constant to obtain a correction for each primary color. . The one or more constants are typically device-specific, ie, typically different for different devices. The correction means include means for applying a respective correction to each of the characteristic values for the corresponding primary color. The means for applying the corrections are constituted, for example, by a unit that subtracts each correction from the characteristic value for the corresponding color.

The replication means comprises a printing beam generator, eg a cathode ray tube, which has a non-linear relationship between the input voltage and the beam intensity. The scanning and generating means include a first unit for supplying a characteristic value to the printing beam generator, and the duplicating means further for adjusting the characteristic value to a non-linear relationship between the input voltage and the beam intensity. A second unit is provided between the first unit and the printing beam generator. The correction means comprises a correction unit between the first and second unit, and the correction unit is designed, for example, to subtract the appropriate correction from each characteristic value.

The first unit is designed as an antilogarithmic unit. This unit, together with the second unit, is preferably in the form of an index table.

The characteristic value is proportional to the luminance of the original drawing and the printing beam intensity.

The inventive procedure for compensating for scattered radiation or light makes it possible to correct the signal for each individual point of the image during the processing stage. This is accomplished by adding or subtracting corrections as needed.

The invention is based on the recognition that during a particular transfer mode using light rays, the scattered light component for each image point arises from the total luminance value for the whole image. Therefore, the average brightness of an image is a measure of the scatter for all image points, and the average brightness for a given color describes the scatter in that color. In this regard, the scattering conditions are different for different colors. The amount of scattered light depends on the characteristics of the particular transfer path, especially the number and thickness of transparent or glass bodies traversed. However, the reflective surface at the edge of the optical path plays a role. In complex systems, the amount of scattered light at the transfer stage is a dimension of 5 percent of the brightness of the entire image.

In an apparatus for carrying out the method of the invention,
The scattered light correction at each transfer stage, and in particular at the scattering and printing stages, is specific to the original to be reproduced and is achieved by subtraction of the scattered light signal that compensates for the scattered light.

The novel features believed to be characteristic of the present invention are:
Particular mention is made in the claims. However, the improved duplication method, together with the structure and operation mode of the improved duplication device,
It will be best understood by reading the following detailed description of specific embodiments when read in connection with the accompanying drawings.

[0031]

1 shows an apparatus according to the invention for the reproduction of an original drawing. Here it is assumed that the original is in color.

The apparatus comprises a scanner 1 which electro-optically scans the original at multiple points. For this purpose, the scanner 1 is provided with a sensor in the form of a linear charge-coupled device with multiple detector cells arranged in rows. The rows extend horizontally, and the charge-coupled devices are moved vertically across the original so that the original is scanned at a series of points that define a set of rows and columns.

The original is scanned sequentially in the three primary colors red, green and blue. This is accomplished by continuously swirling an appropriate color filter to intervene or eliminate in the optical path between the charge coupled device and the original. An electrical image signal is generated for each point of the original in each of the three primary colors red, green and blue. Each signal represents a primary characteristic value that is proportional to the brightness of the corresponding point in each primary color. The signal collectively constitutes the electrical or electronic image of the original.

The original is now electro-optically scanned at 2048 points per row and 1024 points per column so that the resulting image is 2048 in each of the three primary colors red, green and blue.
X1024 image elements or pixels. A correction circuit (not shown) removes an error peculiar to the charge coupled device, for example, an error such as a dark current of a cell of the charge coupled device and various sensitivities. The corrected image signal is digitized and subsequently subjected to electronic image processing in the electronic image processing unit 2. The unit 2 processes the image signal point by point.

The electronically processed image signal is transmitted to the printer 3, which uses a cathode ray tube for printing, for example.
The printer 3 converts the electrical image signal into an optical image and then prints it on a photographic recording material, eg color negative paper. The optical image in the printer 3 is formed point by point by converting the electric image signal. In principle, each pixel is subjected to electronic image processing and subsequently reproduced on the recording material at coordinates corresponding to the coordinates of the respective pixel of the original.

The actual electronic image processing is performed by the electronic processing unit 2
Image processor 4 forming a part of
The image processor 4 is externally controlled by the keyboard 5. The first memory 6 for temporarily storing the image signal is
The second memory 7 for the temporary storage of the image signal is arranged downstream of the image processor 4 when considered in the transmission direction of the image signal.
The intermediate memories 6 and 7 allow the printer 3 to retrieve and print an image from the memory 7, at the same time a new image is loaded into the memory 6 and processed in the image processor 4. The three basic steps of scanning by the scanner 1, the image processing by the image processor 4 and the printing by the printer 3 are made independent with respect to time.

The processed image, which is derived from the image processor 4 and is ready for printing, is observed on the monitor 9 after a temporary storage in a third memory 8 arranged upstream of the monitor 9. Monitor memory 8 and monitor 9
Is a part of the electronic image processing unit 2 for the operator, who evaluates all processed images on the monitor 9 before printing, to enter on the keyboard 5 the necessary corrections of eg color and / or brightness. Conceivable.

When the image processing in the electronic image processing unit 2 is completed, the memory 7 contains a set of signals for the three primary colors red, green and blue optimized for color saturation, contrast and sharpness.

FIG. 2 shows the details of the scanner 1. The reference number 12 identifies the light source which illuminates the transparent original figure 11 completely and uniformly via the reflector 13 and the condenser lens 14.
Original 11 is properly positioned in the ray path from light source 12 using support 30. The original drawing 11 is composed of, for example, a transparent positive image, that is, a positive transparent original drawing. However, in order to explain the effect of scattered light, the original figure 11 is now assumed to be a synthetic original figure with maximum transparency in the lower half. That is, there is simply fog in the lower half and opaque in the upper half. The image of the original figure 11 is formed and focused at the sensor 17 via the objective lens 15. As mentioned above, the sensor 17 is here in the form of a linear charge-coupled device with multiple sensing cells arranged in horizontally extending rows. The charge-coupled device 17 is shifted by a moving mechanism, not shown, in a plane perpendicular to the axis of the optical replication system and the plane of FIG. 2, so that it moves over the original FIG. In this way,
The whole original 11 is scanned by the charge-coupled device 17.
As described above, the charge-coupled device 17 that scans the original image 11 at multiple points generates an output signal proportional to the brightness of each point. Each of these signals comprises a base signal which is uniform in the whole original figure 11. This base signal is the objective lens 15
Attributed to the scattered light emanating from. The base signal is the original map 11
Is added to the luminance signal for the transparent half of.

The color filter is provided at an appropriate position in the optical path, for example, upstream of the objective lens 15, and allows scanning of the color original image. A color filter, generally designated 31, is selectively moved into the optical path. Thus, if the original 11 is color, the series of signals for each of the three primary colors red, green and blue will be obtained by scanning the original 11 three times in succession using different color filters during each scanning operation. , From the charge coupled device 17.

The beam splitter 16 is arranged between the objective lens 15 and the charge coupled device 17. The beam splitter 16 divides a small portion of the total radiation traveling towards the charge coupled device 17 by 90 degrees into three optical receivers or detectors 1.
8a, 18b and 18c are reflected and exposed in one of the primary colors red, green and blue respectively. For example, the optical receivers 18a, 18b, 18c constituted by optical cells are connected to the averaging unit 19. Optical receiver 18a, 1
Each of 8b and 18c is a primary drawing in each primary color.
A signal or value proportional to a luminance of 1 is generated, and the averaging unit 19 averages the signal or value for each primary color. Therefore, the averaging unit 19 produces three average signals or values corresponding to the three primary colors.

The unit 20 for calculating the correction for scattered light is linked to the averaging unit 19. The calculation unit 20 calculates the correction factor or the constant k according to the following equation.
In (i) each of the average signals from the averaging unit 19 is multiplied.

[0043]

(Equation 2)  U (i) = k (i) × U (i) where U (i) is obtained from the averaging unit 19.
And one of the three primary colors red, green and blue.
Is the average voltage representing the average brightness, while U (i)
Is a voltage expressing the scatter correction of each primary color.
Indicate that the corresponding parameter is a function of color
The exponent i is applied to the constant k. Because in the situation
The constant k varies with color, and each of the primary colors
This is because it must be individually determined for.

The output signal of the calculation unit 20 is sent to a correction unit 21 which corrects the image signal or the original characteristic value generated by the charge coupled device 17 for the scattered light. The correction unit 21 is composed of, for example, a summer. The scatter correction calculated for each primary color is applied to all of the image signals for each color, i.e. the respective image signal from each point in the original figure 11. The output of the correction unit 21 issues three sets of signals respectively corresponding to the actual luminance or transparency of the original figure 11 in one of the three primary colors red, green and blue. These output signals corrected for scattered light are transmitted to the electronic image processing unit 2 of FIG.

The constant k (i) must be determined empirically for each device, or at least for each type of device. The constant k (i) takes into account the surface properties of the light elements transmitted by the light ray, the number of surfaces and the reflectivity of the surface located in the path of the scattered light and producing additional scattered light by reflection.

The darkening curve of the copy material or paper constitutes an important factor for the scatter compensation or correction during the exposure of the copy paper.
The dark curve is shown in FIG. 3, where the density of the copy material is
Plotted on the abscissa, and log (log exposure energy) is plotted on the ordinate. The exposure energy is the energy used in the printer 3 for exposing the copy material. The density of the copying material of FIG. 3 ranges from a minimum value of 0.115 to a maximum value of 2.3, while the energy required for exposure is 1.15 for a minimum density of 0.115. It ranges from 75 to 50 for a maximum concentration of 2.3. The minimum density of 0.115 simply represents the density of the copy material when there is fog. The darkening curve is S-shaped. Thus, the degree of darkening increases slightly with increasing exposure energy in the area of lowest density, but the degree of darkening increases at maximum rate at medium density and then approaches saturation above the maximum density of 2.3. When it does, it grows more slowly. The lowest densities in the reproduction of the image, that is to say the densities corresponding to the mere fog of the copying material, are achieved at an energy level of 1.75. Lower energy levels do not produce any noticeable darkening. A general exposure of the copy material at an energy level of 1.75 is essential for the detection of density changes at energy levels slightly above the minimum density.

FIG. 4 shows details of the printer 3 shown in FIG. Unit 24 serves to calculate a correction for scattered light by the method described with reference to FIG. The correction is calculated using the average signal or value for the three primary colors red, green and blue. The average signal or value for each primary color is
It is obtained by averaging the signals or values derived from the scanner 1 and proportional to the luminance of the original 11 and also the intensity of the printing beam of the printer 3 in each primary color. The correction calculated by the calculation unit 24 is transmitted to the correction unit 25 and corrects the processed image signal or the processing characteristic value emitted by the electronic image processing unit 2 for scattered light. The correction unit 25 is composed of, for example, a summer.

The correction unit 25 uses an antilogarithm (antilo).
It is located between the unit 22 and the memory 23. Both the antilogarithm unit 22 and the memory 23 are preferably constituted by an index table. Memory 2
3 is a cathode ray tube 2 for generating a printing beam of the printer 3.
It is connected to 6. There is a non-linear relationship between the input voltage to the cathode ray tube 26 and the screen brightness of the cathode ray tube 26 or the intensity of the printing beam. This relationship is represented by the characteristic line of the cathode ray tube 26. The fitted characteristic line depends on the relationship between the signal magnitude and the brightness represented by the image signal. The memory 23 serves to store the characteristic lines.

The antilogarithmic unit 22 receives a logarithmic luminance signal proportional to the density from the memory 7 of the electronic image processing unit 2. The antilogarithm unit 22 takes the antilogarithm of these signals,
Then, a signal or processing characteristic value proportional to the print beam intensity or the screen brightness of the cathode ray tube 26 is generated. The signal emitted by the antilogarithmic unit 22 representing the scattered light source is transmitted to a correction unit 25, in which case the scattered light correction calculated by the calculation unit 24 is applied to the signal. The correction signal is transmitted to the memory 23 which adjusts or modifies the correction signal by means of suitable characteristic lines. Following adjustment, the correction signal is transmitted to the cathode of cathode ray tube 26.

It will be observed that the correction unit 25 forms part of the means for processing the signal for the cathode ray tube 26.

The screen or cover plate of the cathode ray tube 26 is focused onto the photographic color copying material 29, for example photographic color copying paper, by means of the objective lens 28. A color filter, generally designated 27, is selectively interposed between the screen and the objective lens 28 to continuously expose the copy material to light in the three primary colors red, green and blue.

The light beam 26a which holds the image of the original image 11 passes through the screen of the cathode ray tube 26 together with the light beam 26b of scattered light. The scattered light 27a is also generated at the filter 27, while the additional scattered light 28a is generated by the objective lens 2
Generated by 8. Scattered light 26b, 27a, 28a
Are all taken into account by the constant k '(i) which varies with color and are determined empirically. The constant k '(i) is further dependent on the individual characteristics of the light components 26, 27, 28 and the reflecting surface in the vicinity of the optical path.

The method of compensating or correcting the scattered light in the printer 3 is shown in the diagram of FIG. 5 consisting of two coordinate systems.
One of the abscissas plots the exposure energy applied to the entire surface of the image being printed. The amount of exposure energy is
It takes a range of 0-5. This abscissa corresponds to the ordinate of FIG. 3, whereas the ordinate of FIG. 3 is plotted on a logarithmic scale, while the abscissa of FIG. 5 does not. The second abscissa of FIG. 5 plots on a logarithmic scale the density of the copy material in relation to the exposure energy of the first abscissa.
Thus, an image requiring maximum brightness on all surfaces is exposed to 50 exposure energies, while 25 exposure energies are used for images requiring maximum brightness on half the surface.

One of the ordinates in FIG. 5 plots the amount of scattered light on a proportional brightness scale. More specifically, the amount of scattered light is plotted in percent of the maximum required exposure energy, ie, the ratio of the energy of the scattered light to the maximum required exposure energy multiplied by 100, where the maximum required exposure energy is
Taken as 100 percent. Here, the scattered light quantity is
It is in the range of 1 to 9 percent. The second ordinate in FIG. 5 is
On a logarithmic scale, plot the copy material concentration obtained with different amounts of scattered light. According to FIG. 3, the amount of scattered light that causes fogging of the copy material and produces a minimum density of 0.115 is 3.5 percent. The lower energy levels are darker than those corresponding to the minimum densities.

In FIG. 5, exposure energy = 0, scattered light amount =
Shown is a line starting at point 3.5 and extending upward at an angle of 45 degrees. This line represents the sum of the scattered light generated over the surface of the image during printing of the image with the printing beam and associated with each point of the image. The line is 50
Exposure energy and a maximum of about 9 percent for the amount of scattered light at a copy material density of 2.3, which is increased by increasing the average density of the copy material. Larger amounts of scattered light are not possible. The amount of scattered light present is established from the average exposure energy at the surface of the image. Therefore, the energy of the cathode ray tube 26 for each image point is reduced by an amount equivalent to the expected amount of scattered light. When the jump associated with minimum density is exceeded, as is the case for exposure energies of about 32, the effective exposure energy must then increase linearly.

Correction or compensation for scattered light in the printer 3 is performed as follows.

Before the start of printing, the signal representing the average brightness of the image in the three primary colors red, green and blue is calculated by the calculation unit 2
4 is transmitted. These signals are generated by summing the output signals of the image processor 4 for each of the three primary colors. The processed logarithmic luminance signals stored in the memory 7 for the three primary colors are sequentially transmitted to the antilogarithmic unit 22. When the logarithmic luminance signal for the primary colors is transferred from the memory 7 to the antilogarithmic unit 22, the corresponding color filter 27 has to be positioned in the path of the copying light or printing beam. Based on the expected amount of scattered light,
Scattered light corrections for the three primary colors are calculated from each signal representing the average brightness of the image. The corrections are sent to the correction unit 25, where they are
Is added to or subtracted from the image signal that is proportional to the luminance. After adjustment of each set of corrected image signals in the memory 23 to the appropriate characteristic line of the cathode ray tube 26, the cathode ray tube 26 displays the red, green and blue image corresponding to the different set of adjusted signals in the copy material 29. Are sequentially printed.

Components 22, 25 and 23 need not be individual devices. Instead, the signal processing functions of these three components are performed by a single digital computer, which performs the respective calculations virtually in sequence.

The printing of the image does not have to be done by means of a cathode ray tube. The inventive scattered light compensation procedure is also applied, for example in this case the image signal is retrieved from magnetic or electronic memory and / or the printing is carried out by a laser of suitable color using a deflection device. The applied constant or constants must again be empirically determined. Scattered light, of course, also occurs during recording of the image on the magnetic or electronic image carrier and affects the quality of the image signal mainly in the dark areas. Since the exact scattered light constant of the recorder is unknown during image processing, the scattered light correction according to the invention is performed on the basis of the average estimate for the proportion of scattered light. However, if scattered light correction has already been performed in the recording device, the experimental determination of the scattered light constant k and its application to the stored image signal can be achieved without difficulty.

By using a suitable inverting amplifier,
A positive original (transparent positive image) and a negative original are processed. At each processing stage, the intensity values representing the radiation responsible for the scattered light determine the magnitude of the correction signal and the position of the processing path, which are then subtracted from the image signal.

From the foregoing description, the gist of the present invention has been sufficiently made clear that, from the point of view of the prior art, omitting features that fairly constitute essential characteristics of general and specific aspects of the contribution to the technology. Without applying the current knowledge, the invention can easily be adapted for various applications. Thus, such adaptations are intended to be included within the equivalent meaning and scope of the appended claims.

The main features and aspects of the present invention are as follows.

1. In a method of reproducing an original, scanning the original at multiple points to establish the intensity of the original, and including the at least one characteristic value for each of the points representing the intensity of each point of the original. Generating a value representing the brightness, establishing an average value representing the average brightness of the original, calculating a scatter correction using the mean, and using the correction A method comprising the steps of correcting each of the characteristic values and reproducing the original image based on the corrected characteristic values.

2. The method according to 1 above, wherein the correction is a constant for the original drawing.

3. The scanning step includes directing radiation onto the original and passing the radiation through at least an optical element that causes scattering of the radiation, the correction at least partially scattering the radiation by the optical element. 1 to compensate for
The method described in.

4. The optical element is an objective lens
The method described in.

5. The method of claim 1 wherein the generating step comprises deriving an original characteristic value for each point during the scanning step and processing each of the original characteristic values.

6. 6. The method according to 5 above, wherein the correcting step is performed with the original characteristic value.

7. The method according to claim 5, wherein the correcting step is performed with the processed characteristic value.

8. The reproducing step comprises printing point by point a copy of the original figure, said printing directing a radiation beam at a radiation-sensitive material, adjusting the intensity of said beam point by point, and scattering said beam. Passing the beam through at least one optical element that produces
The method of claim 1 wherein the scattering of the beam by the optical element is at least partially compensated.

9. The method of claim 8 wherein the optical element comprises an objective lens.

10. The method of claim 1 wherein the original is color and the generation, establishment, calculation and correction steps are performed for each of the three primary colors red, green and blue.

11. A scanning step directs radiation to the original, sequentially filters the radiation in the three primary colors when the radiation is transmitted from the original, and detects radiation filtered by multiple radiation sensing elements. And the generating step comprises converting the filtered radiation reaching the element into an output signal representing the original characteristic value of each of the points.

12. 12. The method according to 11 above, wherein the sensing is performed using a charge coupled device including the element.

13. The calculation step is performed using the formula

[0076]

## EQU00003 ## U (i) = k (i) .times.U (i) where U (i) is a voltage expressing the average luminance of the original drawing in one of the three primary colors, and k (i) is , A constant for each primary color and the particular optical system, and U
11. The method according to 10 above, wherein (i) is a voltage expressing correction of each primary color.

14. The duplicating step includes printing a copy of the original by directing a radiation beam at a radiation-sensitive material, the printing including adjusting the intensity of the beam based on the characteristic value, and the correction The method of claim 1 wherein the exposure of the material at least partially compensates for the effects of scattered radiation from the beam.

15. 15. The method according to 14, wherein the printing is done point by point in a cathode ray tube having a screen that causes the scattering of the beam.

16. 16. The method of claim 15, wherein the printing comprises passing the beam through at least one optical element that causes scattering of the beam.

17. The method of claim 16 wherein the optical element comprises a color filter or an objective lens.

18. The method of claim 1 wherein the correcting step comprises subtracting the correction from each of the characteristic values.

19. 2. The method according to 1 above, wherein the characteristic value is proportional to the brightness of each point.

20. In an apparatus for reproducing an original, a means for scanning the original at multiple points and generating a value representing the luminance of the original including at least one characteristic value for each point representing the brightness of each point; ,
Averaging means functionally associated with the scanning and generating means and arranged to establish an average value representative of the average brightness of the original, and functionally established with the averaging means and the averaging Using a correction means arranged to calculate a scatter correction from an average value generated by the means, and a correction functionally related to the scanning and generating means and the calculation means and calculated by the calculation means. Correction means arranged to correct each of the characteristic values, and copying means functionally related to the correction means and arranged to copy the original drawing based on the corrected characteristic values. Device to do.

21. The scanning and generating means comprises a radiation source,
Means for directing radiation from the source along a predetermined path in a predetermined direction, means for supporting an original at a preselected position of the path downstream of the source, and downstream of the preselected position Means for diverting a portion of the radiation from the path at another location of the, and detecting the diverted radiation,
And means for issuing a value representing the total intensity of the original, said detecting and issuing means being designed to transmit the issued value to said averaging means.

22. The scanning and generating means further comprises sensing means at additional locations in the path downstream of the other location, the sensing means being designed to form an image of the original and the directing means. 21 includes an objective lens for focusing the non-detoured portion of the radiation on the sensing means.
An apparatus according to claim 1.

23. 22. The apparatus according to 21 above, wherein the detecting and issuing means comprises a detecting and issuing apparatus for each of the three primary colors red, green and blue.

24. The scanning and generating means includes means for generating characteristic values for each point in each primary color red, green and blue, and the averaging means includes means for establishing an average value in each primary color. , The calculation means includes a multiplication unit for multiplying each mean value by a constant to obtain a correction for each primary color, and the correction means respectively for each characteristic value for the corresponding primary color. 21. Apparatus according to claim 20, including means for applying the correction.

25. 25. Apparatus according to claim 24, wherein said correction means comprises a unit for subtracting the respective correction from the characteristic value for the corresponding primary color.

26. The duplicating means comprises a printing beam generator having a non-linear relationship between the input voltage and the beam intensity, the scanning and generating means comprising a first unit for supplying characteristic values to the generator, and The duplicating means further adjusts the first characteristic value to adjust the characteristic value to the non-linear relationship.
21. Apparatus according to claim 20, comprising a second unit between the unit and the generator, the correction means comprising a correction unit between the first and second units.

27. 27. Apparatus according to claim 26, wherein the generator comprises a cathode ray tube and the first and second units comprise a look-up table.

28. 27. Apparatus according to claim 26, wherein the first unit is an antilogarithmic unit.

29. 27. Apparatus according to claim 26, wherein the correction unit comprises means for subtracting the correction from each of the characteristic values.

30. The scanning and generating means includes means for generating a characteristic value for each point in each primary color red, green and blue, and the averaging means includes means for establishing an average value in each primary color, 27. The above 26, wherein the calculating means includes means for calculating a correction for each primary color, and the correction unit includes means for applying a respective correction to each of the characteristic values for the corresponding primary color. Equipment.

[Brief description of drawings]

1 is a block diagram of an apparatus according to the invention for point-by-point scanning of an original, processing point-by-point of an image of the original and printing point-by-point of the image.

FIG. 2 is a detailed view of a scanner forming a part of the apparatus shown in FIG.

FIG. 3 shows a characteristic darkening curve for a photocopy paper used to print an image in the apparatus of FIG.

FIG. 4 is a detailed view of a printer forming a part of the apparatus shown in FIG.

FIG. 5 is a diagram for calculating scattered light correction for a printer.

[Explanation of symbols]

 1 Scanner 2 Electronic Image Processing Unit 3 Printer 4 Image Processor 5 Keyboard 6 Memory 7 Memory 8 Memory 9 Monitor 11 Original Drawing 17 Sensor 20 Calculation Unit

Claims (2)

(57) [Claims] 1. A method of reproducing an original image, the step of scanning the original image at a plurality of points to establish the intensity of the original image, and at least one characteristic value for each of the points representing the intensity of each point. Generating a value representing the brightness of the original image, including the step of establishing an average value representing the average brightness of the original image, calculating a scatter correction using the average value, Correcting each of the characteristic values using, and copying the original image based on the corrected characteristic values. 2. An apparatus for reproducing an original image, wherein the original image is scanned at multiple points and a value representing the luminance of the original image is generated, which includes at least one characteristic value for each point representing the brightness of each point. Means for activating, an averaging means functionally associated with the scanning and generating means, and arranged to establish an average value representative of the average brightness of the original, and functionally associated with the averaging means. And calculating means arranged to calculate a scatter correction from an average value generated by the averaging means, and being functionally associated with and calculating by the scanning and generating means and the calculating means. Correcting means arranged to correct each of the characteristic values using the corrected correction, and arranged to duplicate the original drawing functionally associated with the correcting means and based on the corrected characteristic values. And the duplication means An apparatus comprising: