JPH0797826B2 - Image processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention outputs the second image data used for image output by the output unit based on the first image data input from the input unit. The present invention relates to an image processing method for storing the relationship between the first image data and the second image data in a storage means.

[Prior Art] Conventionally, in an image processing apparatus such as a digital copying machine,
Some kinds of preset gradations are stored in a memory for image adjustment, and an appropriate gradation is selected from the memories to perform the image adjustment. However, in this method, fine gradation adjustment is often insufficient. For this reason, the white part will be blown out or the dark part will be darkened in spite of trying to produce the bright part. Alternatively, when the tone of the dark part is made bright and the tone of the bright part becomes white, it may happen. This is because selection was made from a limited number of gradations, and it was necessary to be able to arbitrarily set gradations each time.

On the other hand, a technique for arbitrarily setting the gradation characteristics is described in, for example,
As described in Japanese Patent Laid-Open No. 58-103044, a density characteristic curve input while observing the tone of a color original and a gradation characteristic curve of a target halftone image obtained based on the density characteristic curve and input. The correction value is obtained from the above, and the gradation characteristic is not set in consideration of the input characteristic of the input unit and the output characteristic of the output unit. Therefore, when the gradation characteristics are corrected, even if the input / output means have different input / output characteristics, the same correction is performed regardless of the input / output characteristics. It was not possible to make corrections, etc.

[Problems to be Solved by the Invention] The present invention has been made in view of such conventional examples,
An object of the present invention is to provide an image processing method capable of correcting not only the gradation characteristics but also the input / output characteristics of the input / output unit.

[Means and Actions for Solving the Problems] In order to solve the above problems, the image processing method according to the present invention is used in the image output by the output unit based on the first image data input from the input unit. An image processing method in which the relationship between the first image data and the second image data is stored in storage means (corresponding to γ-RAM 6 in the embodiment) to output the image data of Input characteristic information indicating the relationship between the density and the output level of the input means is stored in advance in the first memory (corresponding to the CCDROM 24 in the embodiment), and the relationship between the output image density and the input level to the output means is stored. The output characteristic information shown is stored in advance in the second memory (corresponding to the printer ROM 25 in the embodiment), and the density characteristic information indicating the relationship between the document density and the output image density is input (S51). The second memory The relationship between the first image data and the second image data is stored in the storage means based on the stored output characteristic information and the input characteristic information stored in the first memory (S54- S57) is characterized.

[Embodiment] The image processing apparatus of the embodiment shown in FIG.
, CCD 3, amplifier 4, A / D converter 5, γ-RAM
6, D / A converter 7, triangular wave generator 8, comparator 9, laser driver 10, semiconductor laser 11
A cleaning unit 12, a polygon mirror 13, an electrophotographic photosensitive member 14, a charger 15, a developing unit 16, and a transfer separation unit 17.
Input device 20, RAM 21, CPU 22, program ROM 2
3, a CCD ROM 24, and a printer ROM 25.

The RAM 21 has a pointer P.

In the configuration of FIG. 1, the image electric signal converted by the CCD 3 is amplified by the amplifier 4 and converted into 6-bit digital image data by the A / D converter 5. Then γ-
The image data is γ converted by the RAM 6. After γ conversion, it is converted into an analog signal by the D / A converter 7 and input to one end of the comparator 9. The output signal from the comparator is current-amplified by the laser driver 10 to turn on the semiconductor laser 11 according to the time width. In this way, the laser light is pallet width modulated according to the image signal level and recorded as an output image.

Here, the value of γ-RAM6 is stored in the program ROM 23 according to the printer characteristics stored in the printer ROM 25, the CCD characteristics stored in the CCD ROM 25, and the density characteristics stored in the RAM 21 input from the input device 20. Therefore, the CPU 22 calculates using the pointer P in the RAM 21.

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

FIG. 1 shows an image processing apparatus of the embodiment.

The original 1 is projected by the lens 2 to form an image on the CCD 3 and is converted into an image electric signal. It is also possible to use an image sensor such as a contact sensor instead of the CCD3. The image electric signal is amplified by the amplifier 4 and converted by the A / D converter 5 into 6-bit digital image data. Next, the γ-RAM 6 performs γ conversion on the image data. This part will be described later. After γ conversion, it is converted into an analog signal by the D / A converter 7 and input to one end of the comparator 9. On the other hand, a pattern signal such as a triangular wave generated by a pattern signal generator such as the triangular wave generator 8 is input to the comparator.

The readout of the CCD 3 and the cycle of the triangular wave are synchronized by the synchronization signal φ with the BD signal as a reference.

FIG. 2 shows the relationship between the triangular wave and the image signal after D / A conversion. D
The output of the / A converter 7 has a level of 00H in the case of 6 bits in the white part, and the level of 3FH in the black part is compared with the triangular wave. Midtones will be levels between 00H and 3FH. As a result of being compared, the voltage level is converted into a time width, and the white part is almost low level, but the black part is almost Hig.
The h level is output. The halftone section is set to High level for the time corresponding to the level.

The compared signal is current-amplified by the laser driver 10 and the semiconductor laser 11 is turned on according to the high-level time width. In this way, the pulse width of the laser light is modulated according to the image signal level. The pulse-width-modulated laser light is scanned by a scanning means 13 such as a polygon mirror, and an image is formed on an electrophotographic photosensitive member 14 by a lens (not shown) or the like.
An image is formed on the electrophotographic photosensitive member 14 by a well-known laser beam electrophotographic technique. The charging device 15 charges the electrophotographic photosensitive member 14, and an image signal is projected by the laser beam to form an electrostatic latent image. Next, the developing unit 16 develops the electrostatic latent image with toner to form a visible image, and the transfer separating unit 17 transfers and fixes the visible image on the transfer material to obtain a hard copy. The transfer residual toner is cleaned by the cleaning unit 12, and the process proceeds to the next cycle.

The contents of γ-RAM6 for γ conversion of the image are stored in RAM21 based on the density characteristics input from input device 20 and stored in RAM21.
It is calculated and set by the CPU 22 using the pointer P in 21. FIG. 3 shows this relationship. Third
The first quadrant in the figure shows the relationship between the document density Do and the image density Dp to be printed out, and an arbitrary curve can be input by the input device 20 such as a keyboard, a mouse, a light pen, or a digitizer. It should be noted that the density here is not a density in a strict sense, that is, -1og ₁₀ R (R is the reflectance), and it is more common for an ordinary person to handle the density with the maximum density part normalized to 1. Easy to handle when operating. This result is RAM21 CPU22
Stored through. Further, the relationship between the document density in the fourth quadrant and the CCD output level corresponding thereto is stored in the CCDROM 24 with the document density as an address, and the relationship between the image data in the second quadrant and the recorded image density is recorded with the recorded image density as an address.
It is stored in ROM25.

The contents of γ-RAM6 are calculated as follows. The document density Do is stored in the RAM 21 that stores the input desired density characteristics.
, And print density Dp at that time
Is output as data. Image data is output from the printer ROM 25 using the print density Dp as an address. Similarly, CCD-ROM24 uses C
CCD output is output due to the CD characteristics. This CCD output is used as an address, and the image data at that time is stored as data in the γ-RAM 6. The contents of γ-RAM6 are retained by the backup power supply even if the main unit switch is turned off.
-It is desirable that the universal concentration characteristics can be recovered in case the contents of RAM6 are destroyed.

FIG. 4 shows the γ-RAM incorporated in the program ROM 23.
6 shows the flow chart of the program for calculating the contents of 6. Hereinafter, description will be made step by step. First, in step S50, γ-RAM6
Is cleared. Next, in steps 51-52, the density characteristics input from the input device 20 are stored in the RAM 21 with the original density as an address. After the pointer P is cleared in step S53, the pointer P is used as an address in step S54, and the RAM 21
The output density Dp is read out from the density characteristic stored in step S55, and in step S55, the image data is read out from the printer ROM 25 using the Dp read out in step S54 as an address. In step S56, the CCD output is read from the CCDROM by using the pointer P as an address, and in step S57, the CCD output is read.
The image data read in step S55 is stored in the γ-RAM 6 using the CCD output as an address. While counting up the pointer P in step S59, steps S54 to S59 are repeated until the end of the original density of the address of the density characteristic, and when the end is reached, the process proceeds from step S59 to step S60. At this point, the creation of the contents of the γ-RAM is completed. Step S60
The copy of the original is executed.

The case where the Do-Dp curve is a straight line with an inclination of 45 ° corresponds to the case where the original is faithfully reproduced, but this state is not always the preferable reproduction. For example, when reproducing human skin, it is preferable to set the density range of the skin to be slightly brighter than the original, and to make the γ curve in this region slightly absent. In order to make such a delicate adjustment, it is impossible to select the γ curve from among the preset ones, and it is necessary to make an arbitrary adjustment. In this embodiment, any γ adjustment can be made.

The output characteristics of the CCD3 are linear with respect to the amount of light, but have a Log curve with respect to the document density, and the characteristics of the printer are S-shaped curves. I can't easily guess what will happen. Therefore, it is not easy for a person skilled in image adjustment to input the contents of the straight line γ-RAM6. On the other hand, with the Do-Dp characteristic, it is easy to understand intuitively and can be easily handled by ordinary people. That is, even an ordinary person can easily and arbitrarily adjust the tone of the image.

Although the tone control of the image signal from the original is described in the above description, the tone control can be performed by inputting the image signal from an external device through an appropriate interface. For example, if a video signal is input before the A / D converter 5 or an image signal from an electronic file is input after the A / D converter 5, the tone-controlled content can be printed out.

It should be noted that in the present embodiment, the γ conversion was described, but the idea of the present invention can be effectively used in other digital conversions.
Also, the system of image scan and reverse development where the recording area is irradiated with laser and developed with toner has been explained, but the background area is irradiated with laser and the non-irradiated area is developed with toner. The same effect can be obtained in the developing system.

As described above, according to the present invention, it is possible to provide an image processing apparatus capable of arbitrarily changing the gradation of an image and easily specifying the gradation according to the density of input / output images.

By using the γ conversion unit as in the present invention, it is possible to provide an image processing apparatus capable of gradation reproduction having an inflection point where the density is reversed in a certain area.

[Advantages of the Invention] According to the present invention, the input / output characteristics of the input / output unit can be corrected together with the correction of the gradation characteristics, which enables high-speed correction processing.

[Brief description of drawings]

FIG. 1 is a block diagram of the image processing apparatus of the present embodiment, FIG. 2 is an explanatory diagram of pulse width modulation, FIG. 3 is an explanatory diagram of characteristics of .gamma.-RAM, and FIG. 4 is a flowchart of characteristic generation. is there. In the figure, 1 ... manuscript, 2 ... lens, 3 ... CCD, 4 ...
Amplifier, 5 …… A / D converter, 6 …… γ-RAM, 7 ……
D / A converter, 8 ... Triangular wave generator, 9 ... Comparator, 10 ... Laser driver, 11 ... Semiconductor laser, 12 ... Cleaning unit, 13 ... Polygon mirror, 14
…… Electrophotographic photoreceptor, 15… Charger, 16 …… Developing section, 17…
… Transfer separation part, 20 …… input device, 21 …… RAM, 22 …… CP
U, 23 ... Program ROM, 24 ... CCD-ROM, 25 ... Printer ROM, P ... Pointer.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Moto Kato 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yukihiro Ozeki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Hiroshi Sasame 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tetsuo Saito 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. ( 56) References JP 61-1175 (JP, A) JP 58-48573 (JP, A) JP 60-54567 (JP, A)

Claims (1)

[Claims] 1. The first image data and the second image data for outputting second image data used for image output by the output means based on the first image data input from the input means. Is stored in the storage means in advance, and input characteristic information indicating the relationship between the document density and the output level of the input means is stored in advance in the first memory, and the output image density and the output means are stored. Output characteristic information indicating the relationship with the input level to the input to the second memory, the density characteristic information indicating the relationship between the document density and the output image density is input, and the density characteristic information, the second memory Storing the relationship between the first image data and the second image data in the storage means based on the output characteristic information stored in the first memory and the input characteristic information stored in the first memory. Special Image processing method to be considered.