JPH0237153B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a method for converting image data supplied to a high-resolution image forming apparatus and supplying the converted image data to a low-resolution printer.
The present invention relates to an image reproduction method for a printer that reproduces an image of the same size as the original image.

[Background technology of the invention]

Conventionally, phototypesetting machines and laser printers modulate the brightness of a laser beam and project it onto a photosensitive material as appropriate for printing, or CRT phototypesetting uses a light spot generated by a cathode ray tube to project onto a photosensitive material and print. High-resolution image forming apparatuses such as machines are well known.

Figure 1 is a schematic diagram of a pixel formed in an image forming apparatus using a laser beam with a step-like exposure energy vs. density characteristic. 1 is an arbitrary analog image, and pixel data D (i, j) shown by black dots is The intersection point on the X-axis (i) and Y-axis (j) is scanned and stippled.

Moreover, FIG. 2 is an image diagram formed based on the image data of FIG. 1, and G (i, j) is a forming pixel,
By tracing the contours of the plurality of forming pixels, a desired output image 2 is drawn in the range shown by the solid line.

In FIG. 1, black dots indicate that data D(i,j) is "1". The pixel data D(i,j) formed in this way are arranged with forming pixels G(i,j) in a range surrounded by a circle on the grid shown in FIG. 2, respectively. That is, pixel data D(i,j)
The laser beam, etc. is modulated on and off by the pixel G.
(i, j) to form an output image 2 that approximates the desired image. Furthermore, in this type of image forming method, the resolution of the output image is regulated by a pitch P determined based on the pixel size.

Further, high-resolution image forming apparatuses and the like usually form output images on photosensitive materials. However, if an uncorrected output image is directly outputted onto a photosensitive material and used as a galley (force sample for proofreading instructions) for proofreading work, the cost of the photosensitive material increases. Therefore, conventionally, at the proofing stage, the output is output to a printer with a lower resolution than the image forming device to make corrections, etc., and only the final output after proofreading is outputted to the high resolution image forming device. I was saving money.

[Problems with background technology]

When outputting pixel data from an image forming device with high resolution (for example, a scanning pitch of 32 lines/mm) to a printer with a low resolution (for example, a scanning pitch of 16 lines/mm), the high-resolution pixel data can be directly transferred to the low-resolution printer. If the output image is output using the image forming apparatus, the output image will be twice the size of the output image of the image forming apparatus. Therefore, by converting the high-resolution pixel data to 1/2, it is possible to obtain an output image of the same size as the image forming apparatus.

As a conventional conversion method, there is a simple thinning method in which images are simply thinned out in the X direction and Y direction according to the reduction ratio.

For example, in an image forming apparatus, for pixel data having a line width of 3 dots as shown in FIG. 3a, even numbered rows and columns in the X and Y directions are simply drawn as shown in b. However, ● indicates “1” and 〇 indicates “0”. Then, by using the pixel data of b as reproduction data of the printer such as c, the printer outputs at the scanning pitch P based on the reproduction data.

However, in the case of such simple thinning, if the column phase shifts by one dot even though the image line width is the same as a, as shown in Figure 3d, the even numbered columns as in e are thinned out in the same way as in b. As a result, the reproduced data f obtained will be an output result different from the above-mentioned c. In particular, when outputting characters as an output image, the simple thinning method, which is a conventional conversion method, has the disadvantage that the line width of the characters may differ in some parts, and thin line parts may be omitted. This is the same even if odd columns are thinned out.

[Purpose of the invention]

The present invention provides an image reproduction method for a printer that eliminates quality deterioration caused by converting high-resolution pixel data of an image forming device into low-resolution pixel data for a printer and outputting the same, and reproduces a faithful image. It is.

[Summary of the invention]

The present invention provides an image reproduction method for a printer in which the dot reproduction pitch P in the main scanning direction perpendicular to the printing medium feeding direction is fixed to a predetermined value.
The original data of N _i ×N _j dots may be sampled in a staggered manner, or the original data of N _i ×N _j dots (however, n _i
=N _i /2) is supplied to the printer as reproduction data, and the printer reproduces dots by setting the dot reproduction pitch in the sub-scanning direction of the printer to approximately P/2. This provides a reproduction method.

That is, high-resolution pixel data as shown in FIG. By shifting the row in which even-numbered column pixel data is sampled (even-numbered row in this case) by one dot to the left, we can obtain n _i ×N _j (n _i =N _i /2) reproduced data like c. Can be done. This reproduced data is output at a scanning pitch of P in the main scanning direction and at a scanning pitch of P/2 in the sub-scanning direction. As a result, pixel data of the same image line width whose column phase is shifted by one dot from a as shown in Fig. 3d is sampled in a staggered manner as shown in e in the same manner as described above. The reproduced data f is obtained with approximately the same linear density as the reproduced data c.

[Embodiments of the invention]

FIG. 5 is a block diagram showing an embodiment of an image forming apparatus and a printer suitable for implementing the present invention.

In the figure, 3 is a storage unit that stores N _i ×N _j high-resolution original pixel data, 4 is an image forming device that outputs an image based on the high-resolution original pixel data, and 5 is a storage unit that stores high-resolution original pixel data. A data conversion unit converts into low-resolution pixel data for reproduction of n _i ×N _j (n _i =N _i /2), and 6 is a printer that outputs an image based on the low-resolution pixel data for reproduction.

The image forming device 4 includes a recording unit 4a using a CRT, a laser beam, etc., and a recording material 4 such as a sensitive material or film.
b, a drive source 4c such as a pulse motor that sends the recording material 4b in the sub-scanning direction, and a motor driver 4d that drives the motor 4c.

The N _i ×N _j high-resolution original pixel data 9 stored in the storage unit 3 is sequentially sent to the recording unit 4a. When the separately input enable signal 8 for permitting recording in the main scanning direction is active "1" as shown in FIG. Record it on material 4b.

When one scan is completed, a step signal 10 for feeding the recording material 4b in the sub-scanning direction is sent to the motor driver 4d, and the motor driver 4d drives the motor 4c to feed the recording material 4b in the sub-scanning direction. The above is a description of the case of outputting to an image forming apparatus.

Next, the case of outputting to a printer will be explained.

The printer 6 includes a recording section 6a that performs recording using dot impact, thermal head, etc., and a recording section 6a that performs recording using dot impact or thermal head,
It is composed of a recording material 6b such as thermal paper, a drive source 6c such as a pulse motor that sends the recording material 6b in the sub-scanning direction, and a motor driver 6d that drives the motor 6c.

First, high-resolution original pixel data 9 of N _i ×N _j is sent to the data converter 5 . In the data conversion unit 5, by sampling the pixel data of N _i ×N _j in a staggered manner as shown in FIG. 4b, n _i ×N _j (n _i =N _i /2 ) is converted into playback data 9'.

On the other hand, the data converter 5 converts the clock signal 7
A signal 7' obtained by dividing the frequency by 1/2, a signal 8' synchronized with the enable signal 8, and the above-mentioned reproduced data 9' are output to the recording section 6a. As shown in FIG. 7b, when the enable signal 8' is active, the recording section 6a
The reproduction data 9' is recorded on the recording material 6b at a scanning pitch P in synchronization with the clock signal 7'. Each time one scan is completed, a step signal 10 is sent to the motor driver 6d, and the motor driver d drives the motor 6c to perform feeding at a scanning pitch of P/2 in the sub-scanning direction.

Next, an example of a configuration for realizing the operation of the data conversion section 5 described above will be explained using FIGS. 6 and 7.

As shown in FIG. 6, the clock signal 7 is frequency-divided by 1/2 by a 1/2 frequency divider 5a and outputted as a clock signal 7' to the printer 6. This clock signal 7' is sent to an AND circuit 5f via an AND circuit 5d and an inverter 5e.

Similarly, the enable signal 8 is divided into 1/2 by the 1/2 frequency divider 5b and outputted from the AND circuit 5d.
This becomes the gate signal 11 of the AND circuit 5f.

When gate signal 11 is "0", AND circuit 5d is selected via inverter 5c, and clock signal 7' is sent as clock signal 12 to latch circuits 5h and 5i via OR circuit 5g.

When the gate signal 11 is “1”, the AND circuit 5
f is selected, and the inverted signal of clock signal 7' is sent as clock signal 12 to latch circuits 5h and 5i via OR circuit 5g.

The latch circuit 5h latches the enable signal 8 at the falling edge of the clock signal 12 and outputs an enable signal 8'.

The latch circuit 5i latches the high-resolution original pixel data 9 and outputs reproduced data 9' in the same manner as described above.

The clock signal 7' converted in this way,
The enable signal 8', reproduction data 9' and step signal 10 are sent to the printer 6.

FIG. 7b shows the clock signal 7', enable signal 8', reproduced data 9', step signal 10, and gate signal 1 in the data converter 5.
1 shows the timing waveform of No. 1.

As described above, the gate signal 11 alternately selects the clock signal obtained by dividing the clock signal 7 by 1/2 and its inverted clock signal, and outputs the clock signal 12. That is, depending on the selected clock signal, sampling of odd or even columns of pixel data in one scan is determined, and as a result, the high-resolution original pixel data 9 is sampled in a staggered manner.

The reproduction data 9' sampled in this way is sequentially sent to a low-resolution printer 6 with a pitch in the main scanning direction of P and a pitch in the sub-scanning direction of approximately P/2, and is thereby sent to the high-resolution output device 4. To reproduce an image that has the same size as an output image and has few omissions from the original image.

〔Effect of the invention〕

According to the present invention, reproduced data is obtained by sampling high-resolution original pixel data in a staggered manner, and is output at a predetermined pitch P in the main scanning direction, and is sent at a pitch of P/2 in the sub-scanning direction. By doing this, characters and the like can be reproduced with an apparently almost uniform line width, and it is also possible to prevent thin lines from being lost due to simple thinning. and,
Overall, it is possible to faithfully reproduce an output image obtained by a high-resolution image forming apparatus.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of pixel data formed by an image forming apparatus using a conventional laser beam, Figure 2 is an image diagram drawn based on pixel data of the conventional method, and Figure 3 is a diagram of an image drawn based on the conventional simple thinning method. FIG. 4 is a schematic diagram of formed pixel data that has been thinned out, FIG. 4 is a schematic diagram of formed pixel data according to the method of the present invention, and FIG. 5 is an embodiment of an image forming apparatus and printer suitable for carrying out the present invention. FIG. 6 is a block diagram showing an embodiment of the structure of the data conversion section 5, and FIG. 7 is a diagram showing timing waveforms of FIG. 6. 3... High-resolution original pixel data storage section,
4... Image forming device, 5... Data converter, 5
a, 5b...1/2 frequency divider, 5c, 5e...inverter, 5d, 5f...AND circuit, 5g...OR circuit, 5h, 5i...latch circuit, 6...printer.

Claims (1)

[Claims] 1. In an image reproduction method for a printer in which the dot reproduction pitch P in the main scanning direction is fixed, n _i ×N _j obtained by sampling original data of N _i ×N _j dots in a staggered manner. Dot (however, n _i
=N _i /2) is supplied to the printer as reproduction data, and the printer reproduces dots by setting the dot reproduction pitch in the sub-scanning direction of the printer to approximately P/2. How to play.