JPH07298077A - Color printer having plural color correction systems - Google Patents

Abstract

PURPOSE:To output an image subject to optimum color correction when color data are printed out with respect to a color printer. CONSTITUTION:A color printer has plural color correction systems and is provided with plural color correction circuits 6A-6N corresponding to the color correction systems, a switch circuit 5 selecting one of the plural color correction circuits 6A-6N and a simulation circuit monitoring the result of color correction by the switch circuit 5, and one system is selected among the color correction systems provided to the printer and an image is simulated when a color at the outside of a print characteristic range based on a coloring characteristic of the printer is degenerated into the printable color range and the color printed out by the printer is known.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color printer,
The color correction method of a color image output by a color printer can be monitored in advance so that the user can select an appropriate color correction method before printing.

[0002]

2. Description of the Related Art Various types of color printers have been developed. In either method, color development is realized by superposing layers of dye or pigment on recording paper. The so-called subtractive color mixing principle can be applied to color development.

On the other hand, the color forming method on the CRT screen is RGB.
It is based on the principle of additive color mixing of three colors, and when reading with a scanner, RGB is the three primary colors of additive color mixing.
The original is read by the reflection from the light source.

As described above, the color forming methods are fundamentally different from each other, even if it is called a single bit of color.

However, the most commonly used color printer is a hard copy of a color image created on a CRT screen, a copy of a photograph or an illustration read by a scanner, or a print of the image processed by the computer. . Further, the dye or pigment used in the color print, the phosphor of the CRT, the light source of the scanner (coloring spectrum of the phosphor) and the like have different characteristics. Therefore, there is a problem that the desired color is not produced even when the result of working on the CRT is printed in color.

In the following description, C is used for simplicity.
The following description focuses on printing a color image created on the RT with a printer.

When the lightness is plotted along the vertical axis and the saturation is plotted along the horizontal axis, and the hue is taken in the circumferential direction, the printer or C
The color development range of RT can be plotted. Generally, the color range of a color printer does not match the color range of a CRT. Various methods have been proposed as to why this non-matching range is printed by a color printer.

However, since the conventional printers were not equipped with these color correction systems, it was not known until the printing what kind of color the color printer would display on the CRT. .

In order to solve this, there is a concept of device-independent color. This sets a virtual absolute color coordinate space, and the CRT for that virtual absolute color space
The characteristics of the printer and the printer are stored in a table, and the color correction is performed based on the data.

In order to implement such device-independent color, it is necessary to grasp the characteristics of the printer under all conditions, and to create a profile representing the characteristics of the printer, a highly specialized method is required. It is very costly because it requires knowledge, and if the dyes and pigments used in the printer are different or the coloring conditions are changed, it is necessary to re-collect all the data. There was a flaw.

[0011]

SUMMARY OF THE INVENTION The present invention eliminates the above-mentioned drawbacks, provides a color correction system monitor in advance, and provides a color printer which allows a user to select an appropriate color correction system. Is.

[0012]

SUMMARY OF THE INVENTION According to the present invention, a color printer is provided with a plurality of color correction methods, and a plurality of color correction circuits corresponding to the respective color correction methods and one of the plurality of correction circuits are provided. This is achieved by providing a switch circuit for selecting the color change ratio and a simulation circuit capable of monitoring the color correction result corrected by the switch circuit.

Further, in addition to the above configuration, the simulation circuit is effectively achieved by providing a monitor area selection circuit for outputting a partial image on a monitor as needed.

[0014]

According to the above construction, an appropriate color correction method can be selected from a plurality of color correction methods, and the color correction method selected before printing is appropriate if necessary. It is also possible to monitor whether or not. Furthermore, when monitoring is performed, the printer can specify and output a print sample in which the image is color-corrected by the built-in correction method, or a part of it, a reduced image, and so on. It is possible to decide whether to perform printing with the correction method or to reconsider another correction method, and it is possible to perform more accurate color correction.

As described above, the color printer of the present invention is
It is possible to use the color printer effectively at a low running cost because it is possible to monitor output regarding the color correction method before obtaining a complete print output of one sheet and select the optimum color correction method. it can.

[0016]

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a flow chart showing the control flow of the color printer according to the present invention. Reference numeral 1 is a print signal input buffer, 2 is a circuit for determining whether or not to perform color correction, 3 is a circuit for outputting an image corrected by each correction circuit incorporated in the printer, 4 is a correction method selection circuit, 5 is a switch, and 6A. 6n is a color correction circuit according to each method, 7 is a circuit for determining whether or not to monitor a partial image of interest in the entire image, 8 is a circuit for selecting an area to be printed on a monitor, 9 is a monitor image output circuit, and 10 is a monitor image output circuit. Is a circuit for determining whether to switch to another correction method,
Reference numeral 11 is a circuit for printing the entire image, and 12 is a color correction method used last time.

An image signal from a communication circuit such as a computer or a network is temporarily transferred to the print signal input buffer 1
Will be stored in. When one page of image is stored, the judgment circuit 2 for deciding whether or not to perform color correction monitoring is entered.

Here, in general, a message for asking the user to determine whether or not to perform the same monitoring is output on the display, and a response thereto is waited.

If the user response is No, the printer immediately starts printing using the data in the print signal input buffer. At this time, the previously used color correction method 12 is preferably applied.

When the user responds Yes, the printer first executes the simulation 3 of the output image by each color correction method. Here, the result of monitoring the print signal when the color correction method built into the printer is applied is monitored.

In the preferred embodiment, the print signal is reduced and printed, and a print result obtained by color-correcting a plurality of sheets and a color-correction method are described together in one page. Is.

In another embodiment, the color printer is equipped with a color display device, and the color correction effect is simulated on the display. In this case, the color printed and the color displayed on the display are different in principle, and the color of the print itself cannot be known from the color of the display. Therefore, in this method, the print result is estimated by viewing the color correction method exaggerated to some extent on the display. However, the advantage in this case is that the cost of consumables can be reduced because the printing result can be known without consuming the expensive papers for color printers, inks, dyes, pigments and the like. Even in this method, a user who is accustomed to using the printer can sufficiently estimate the print result from the color of the display.

Next, the user is requested to select the color correction method 4 from the result of the simulation. The printer includes correction circuits 6A, 6B, 6C, ...
6n is built in, and color correction of color data is performed based on each correction principle. A typical color correction principle will be described later. When the user selects one color correction method, the data input to the print signal input buffer is corrected. The selection method may be a hardware-type changeover switch 5 provided in a part of the printer housing, or a soft selection by moving a cursor via a display device.

Further, for the convenience of the user, it is possible to monitor a partial image of the image data input here, if necessary. In most cases, the areas where color correction must be applied are not distributed throughout the image. Therefore, a user who has become accustomed to the art should be aware of the necessity of designating a part of the image and performing actual printing on the part with the actual size.

Such a user is guided to the process of setting the next print area by answering Yes to the inquiry 7 whether to monitor the partial image. On the other hand, No
In response to the above response, the printer skips the following steps and immediately starts printing using the data in the print signal input buffer. At this time, the previously used color correction method 12 is preferably applied.

Next, the user uses the display device and arrow keys to instruct the computer which part of the entire image is to be monitored by the print area selection circuit 8.

The partial image selected by the monitor image output circuit 9 can be monitored. Here, as in the case of the monitoring method, it is also possible to actually print with a color printer or to monitor it on the display.

Further, the user confirms 10 whether the color correction method is acceptable. If the user is not satisfied with the correction result, the user returns to the correction method selection circuit 4 again,
You can repeat the operations so far.

FIG. 2 is a schematic diagram showing the principle of the color correction method.

Reference numeral 21 is a saturation axis, 22 is a lightness axis, and 23 is a hue arranged in the circumferential direction along the lightness axis. Reference numeral 24 denotes a monitor color expression range that represents a range of colors that the monitor can express under a certain hue when represented by such a coordinate system. Reference numeral 25 is a color expression range of the same printer.
A group of arrows 26 is an arrow for associating which color of the printer substitutes a color that cannot be expressed by the printer with the color of the monitor. 27, 27 ', 2 with hatching
7 ″ is a color expression range that can be expressed by the printer after color correction.

Although the term "circuit" is used in the above description, it is needless to say that the term "circuit" does not necessarily mean hardware but can be replaced by a program or the like that exhibits the same function in software. Absent.

FIG. 2 shows three typical color correction methods that are generally used. (a) is said to be a relative brightness preservation type, in which the brightest color of the input image corresponds to the white point of the printer and all other colors correspond to the white point within the color reproduction range of the printer. It is a mapping that is maintained. In this method, the relative relationship between colors is maintained, so that it is easy to match human perception characteristics.

(B) is called a common area storage type, in which the color that can be expressed by the printer is not adjusted, and the lightness of the color that cannot be expressed is stored as much as possible, while the outermost color of the color reproduction range of the printer. It is a method to replace. With this method, the colors that can be represented by the printer are faithfully represented, but the relative relationship between the colors collapses,
There is a drawback that the number of colors that can be expressed is reduced. Also,
The saturation of the printed image is reduced.

(C) is called a color saturation preserving type, and (b)
In this method, the color that can be expressed by the printer is not adjusted, and the color that cannot be expressed is replaced with the outermost color in the color reproduction range of the printer while preserving the saturation as much as possible. With this method, the colors that can be expressed by the printer are faithfully expressed, but the relative relationship between the colors is broken, and the number of colors that can be expressed is reduced. Also, the contrast of the printed image is reduced.

As for the fields to be applied, (a) is applied to a photographic image having many colors, (b) is applied to an image having many single colors such as an illustration,
It is considered that (c) is suitable for printing computer graphics and the like.

FIG. 3 is a front view showing the appearance of the color printer according to the present invention. Reference numeral 31 is a printer housing, 32 is a display device, 33 is an arrow key for instructing the movement of a cursor, 34 is a key for inputting numbers and the like, 35 is a printing paper cassette, and 36 is a printing paper discharging section.

As described above, the display 32 outputs a message from the determination circuits 2, 7 and 10 for asking the user to make a determination as described above, when the correction method selection 5 is requested, and the monitor image output 8 and the print area selection 9 are made. In the case of, it is used to output a message or cursor so that the user can give a correct instruction.

The arrow key 33 is mainly used as an input means for controlling movement of the cursor, and 34 is a numeral input or Yes / Yes.
This is for inputting a No instruction.

[0040]

According to the present invention, since the color printer is configured as described above, the user can monitor the print result of the color correction method before printing in advance, and if it is not satisfied, the other color correction method can be used. Can be changed and printed.
Therefore, you can get the expected color print,
It is possible to eliminate the waste of making several trial prints in order to obtain one color print, and it is possible to minimize the expensive consumables of the color print.

[Brief description of drawings]

FIG. 1 is a flowchart showing a control flow of a color printer according to the present invention.

FIG. 2 is a schematic diagram showing the principle of a color correction method.

FIG. 3 is a front view showing the outer appearance of the color printer according to the present invention.

[Explanation of symbols]

1 is a print signal input buffer, 4 is a correction method selection circuit,
6A to 6n are color correction circuits according to the respective systems, 9 is a monitor image output circuit, 11 is a circuit for printing the entire image, 21 is a saturation axis, 22 is a brightness axis, and 23 is a circumferential direction along the brightness axis. Is a hue, 24 is a color expression range of a monitor, and 25 is a color expression range of a printer. 27, 27 ', and 27 "are color expression ranges that can be expressed by the printer after color correction.

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Claims (2)

[Claims] 1. A color printer, comprising a plurality of color correction methods, a plurality of color correction circuits each corresponding to the color correction method, and a switch circuit for selecting one of the plurality of correction circuits. And a simulation circuit capable of monitoring a color correction result corrected by the switch circuit, the color printer having a plurality of color correction methods. 2. The color printer having a plurality of color correction methods according to claim 1, wherein a monitor area selection circuit for outputting a partial image on a monitor is added to the simulation circuit as needed.