JPH05176159A - Image forming device - Google Patents

Abstract

PURPOSE:To convert and output inputted picture data into multi-value processing data with a desired resolution and to execute the conversion of resolution flexibly corresponding to various levels of resolution without complicated configuration and with less deterioration in the quality of the picture. CONSTITUTION:A picture is expanded in a picture memory 52 according to the resolution of picture data inputted through an input output interface 53. The expanded binary picture data are converted into multi-value processing picture data by a binary/multi-value processing picture data by a binary/multi- value processing conversion section 56, the resolution of the multi-value processing picture data is converted at a magnification/reduction circuit 57 according to the magnification/reduction algorithm and the resulting data is outputted to a printer section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus. More specifically, it relates to an image forming apparatus having a function of converting resolution of image data.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus having a recording unit such as a page printer executes recording with a density in which the density of one pixel is expressed by a binary value. Therefore, when the resolution of the image data to be recorded is different from the resolution of the recording unit, the resolution of the recording unit is changed on the image forming apparatus side to match the resolution of the image data, or the binary data I added resolution conversion processing as it was.

Image data whose resolution can be changed,
For image data such as vector data, the resolution of the developed binary image data is determined by the resolution of the recording unit. In the image forming apparatus, the image data is expanded into binary image data according to the resolution of the recording unit and output from the recording unit.

However, in the case where the input image data and the recording unit of the image forming apparatus have different resolutions as described above, it is possible that the storage unit of the image forming apparatus has several kinds of resolutions. Not only does the structure of the device become complicated and the cost increases, but there is also the drawback that only the resolution prepared in advance can be supported. Further, when the resolution is converted as it is in binary image data in the image forming apparatus, there is a drawback that the quality of the image is largely deteriorated.

Further, when the vector data and the like are expanded into binary image data, it takes a long time to expand the image data in the image forming apparatus if the resolution of the recording section is high.

The present invention has been made in view of the above problems, and converts input image data into multi-valued image data having a desired resolution and outputs the converted image data without complicating the structure. An object of the present invention is to provide an image forming apparatus that performs flexible resolution conversion that can support various resolutions with less deterioration of image quality.

Further, for image data having variable resolution, it is possible to develop the image at a desired resolution and then convert it to a resolution suitable for the output device, and develop the image at a resolution lower than that of the output device. The purpose is to shorten the image development time.

[0007]

In order to achieve the above object, an image forming apparatus according to the present invention sets a ratio between the resolution of input multi-valued image data and the resolution of multi-valued image data to be output. Resolution ratio setting means, pixel interpolation means for interpolating and determining the value of each pixel of output multi-valued image data based on the ratio set by the resolution ratio setting means and the input multi-valued image data, and the pixel Image data output means for outputting the output multi-valued image data generated by the interpolation means.

According to another aspect of the present invention, a binary / multivalue conversion means for converting the input binary image data into multivalued image data, and the resolution of the input binary image data and the number of outputs to be output. A resolution ratio setting means for setting a ratio with the resolution of the value image data, and an output multi-value based on the ratio set by the resolution ratio setting means and the multi-value image data generated by the binary multi-value conversion means. An interpolation unit that determines the value of each pixel of the image data and an image data output unit that outputs the output multi-valued image data generated by the pixel interpolation unit are provided.

Further, according to another invention, in the above-mentioned image forming apparatus, when the input image data is an image data of a format capable of changing the resolution, the input image data is a binary image of a specified resolution. It further comprises data expansion means for expanding the data on the image memory.

[0010]

The multi-valued or binary image data input by the above configuration is converted into multi-valued image data according to the ratio set by the ratio of the resolution of the input image data to the resolution of the output image data. .. As a result, multivalued image data having a desired resolution can be obtained regardless of the resolution of the input image data.

For image data whose resolution can be changed, the input image data is expanded into binary image data having a desired resolution, and this is further converted into multivalued image data having a desired resolution.

[0012]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

<Embodiment 1> In Embodiment 1, an image forming apparatus in which a digital copying machine is implemented as a multi-valued printer will be described. FIG. 1 is an overall view of a digital copying machine used in the image forming apparatus according to the first embodiment. Normally, a digital copying machine is provided with a printer 33 capable of printing multi-value density data for each pixel in order to output an image read by an image reading unit (image reader 31) with high quality. It has become.

In FIG. 1, the originals stacked on the original feeding device 1 are sequentially conveyed one by one onto the original table glass surface 2. When the document is conveyed, the lamp 3 of the scanner unit 4 is turned on and the scanner unit 4 moves to illuminate the document. The reflected light from the document is reflected by the mirrors 5, 6,
It passes through the lens 8 via 7 and is input to the image sensor unit 9. The above is the configuration and functions of the image reader 31.

FIG. 2 is a block diagram of the image forming apparatus according to this embodiment. The output signal from the image reader 31, that is, the image signal output from the image sensor unit 9, is an image signal control circuit 32 controlled by the CPU 30.
Entered in. In the image signal control circuit 32, the input image data is converted into digital multi-valued image data, further processed, and reaches the printer unit 33.

From the image signal control circuit 32 to the printer section 33
The exposure controller 10 controls the laser
The beam is controlled to irradiate the photoconductor 11 as an optical signal.
The latent image formed on the photoconductor 11 by the irradiation light is the developing unit 1
3 is developed. Transfer paper is conveyed from the transfer paper stacking unit 14 or 15 at the same timing as the latent image, and the developed image is transferred at the transfer unit 16. The transferred image is fixed onto the transfer paper by the fixing unit 17, and then discharged from the paper output unit 18 to the outside of the apparatus.

Next, a configuration in which the printer unit 33 of the image forming apparatus outputs multivalued density data will be described. The printer unit 33 according to the present embodiment uses a laser beam as an exposure unit that scans line by line, and a signal for controlling the laser beam is modulated to change the irradiation area on the photoconductor 11. Area gradation is executed for each pixel so that it is expressed in multivalue.

FIG. 3 is a circuit diagram for producing and outputting a signal for modulating a laser beam from an image signal input to the printer section 33. The image density data of the image signal input to the printer unit 33 is a digital value.
When this value is input to the D / A converter 41 for each pixel, it is converted into an analog value and input to the comparator 42. From the triangular wave generator 40, a triangular wave used for comparison with the image signal is input to the comparator 42.

FIG. 4 is a diagram showing the relationship between the image signal 101 and the triangular wave output 102 input to the comparator 42 and the exposure control signal 103 output from the comparator 42. The exposure control signal 103 is output as a pulse width modulation signal (PWM) corresponding to the level of the image signal 101. 1
If the irradiation time of the laser beam for each pixel in the scanning line is controlled according to this exposure control signal 103, the irradiation area for each pixel can be changed, so that area gradation can be realized.

Next, the binary image generation / storage device 34 of FIG. 2 will be described. FIG. 5 is a detailed block diagram of the binary image generation / storage device 34. This binary image generation / storage device 3
Reference numeral 4 is for expanding the image data based on the data according to the page description language sent from the external computer. The page description language mentioned here is a language system for expressing the image data for each pixel output by a page printer or the like in a command format.

The interface 53 is an input / output interface with an external computer. When the CPU 50 receives the page description language data input via the input / output interface 53, the CPU 50 interprets the content and stores the binary image data of one page sentence on the image memory 52 via the memory controller 51. To expand.
When the development of the image data is completed, the CPU 50 causes the communication line 54
Via the image data bus 55 to prepare for communication with the CPU 30 via the image data bus 55. When transmitting the image data to the image signal control circuit 32, the image data is converted through the binary / multivalue conversion unit 56 and the enlargement / reduction circuit 57 of FIG. The binary-multivalue conversion unit 56 assigns the binary values of the image data expanded on the image memory 52 to the maximum value and the minimum value of the multivalued data, and outputs them as multivalued data. The enlarging / reducing circuit 57 performs resolution conversion on the received multi-valued data in the main scanning direction and the sub scanning direction by the following algorithm.

First, referring to FIG. 6, in the conventional method of enlarging / reducing a multi-valued image, pixels of main scanning are x / (xy)%.
The case of enlarging will be described as an example. In the case of the same size, there is no problem because the actual output position 61 of FIG. 6 corresponds to the actual read position 63 of the original image data, but when enlarging, the image signal was input at the virtual read position 62. Think of things. If the image data of the virtual read position 62 is output to the actual output position 61, the image is enlarged. The image density at the virtual reading position 62 is interpolated from the density value of the image signal input at the actual reading position 63 based on the following equation O2 = {R1 · y + R2 · (x−y)} / x In the case of sub-scanning, this algorithm may be applied to each scanning line.

FIG. 7 is a diagram showing a state in which resolution conversion is carried out by the scaling circuit described above. If the virtual read position 62 in FIG. 6 is used as it is as the actual output position 71, the resolution conversion has been performed. As shown in FIG. 7, if the pixel at the virtual read position is interpolated so as to be enlarged, the resolution is converted to a higher resolution. Further, if the pixel at the virtual read position is interpolated so as to be reduced, the resolution will be converted to a lower resolution.

The operation of the copying machine of the first embodiment will be described based on the above description. Normally, the content of an image described in the page description language is targeted for the resolution corresponding to a dedicated page printer. As an example, the printer unit 33 of the image forming apparatus according to the present exemplary embodiment uses 400 dots (4 dots) per inch.
00 dpi) pixels are output, and data according to a page description language corresponding to a page printer that outputs 240 dots (240 dpi) pixels per inch is sent to the binary image generation / storage device 34. Suppose In this case, first, the CPU 50 stores 2 in the image memory 52.
Image data is developed at a resolution of 40 dpi. And
When transferring the expanded data to the printer unit 33 of the copying machine, the data is set in the enlarging / reducing circuit 57 so as to be expanded at a magnification of (400/240) × 100 = 166.6%. As described above, the image data is converted into multi-valued data by the binary multi-valued converter. Thereafter, the enlarging / reducing circuit executes pixel interpolation at the set magnification, and the pixel is transferred to the printer unit 33. The printer unit 33 prints the transferred image data 400d.
Output with pi. In this way, image data input at 240 dpi can be output at 400 dpi.

As described above, according to the first embodiment, 2
By converting the value image into a multi-valued image and further converting the resolution by the scaling function, it is possible to suppress the deterioration of the image and easily convert the resolution of the image data to a desired value. Therefore, image data of various resolutions can be recorded. In the first embodiment, the printer unit of the digital copying machine can be used by converting the resolution, and the image forming apparatus has both the functions of the copying machine and the page printer. The effect of being provided occurs.

<Embodiment 2> In Embodiment 2, a case will be described in which the page description language described above handles data independent of resolution, for example, vector format data.
The configuration of the device is similar to that of the first embodiment. Resolution-independent means that the binary image generation / storage device 34 corresponds to the specified resolution and expands according to a resolution-dependent constant when the page description language data sent is vector format data. By doing so, it is possible to support any resolution.

However, in the configuration in which the CPU 50 expands the image memory 52 as in the present embodiment, the higher the resolution, the longer the time required to expand the data. However, the binary / multivalue conversion unit 56 and the enlargement / reduction circuit 57
Since it can be processed in real time, if you expand it to a lower resolution within the range that does not affect the image quality, it is possible to considerably reduce the time until the actual image data is output from the copying machine. Becomes Comparing the development time of the image data by the number of pixels in the same area, there is a nearly triple difference between (400) ² / (240) ² = 25/9 at 400 dpi and 240 dpi, so the effect is great. FIG. 8 shows an example of a flowchart when image data from an external computer connected to the interface 53 is developed at a low resolution.

In step S1, reception from the external computer is started. In step S2, the development resolution instruction data is received. This development resolution is set to a value lower than the resolution output to the image signal control circuit. In step S3, the page description language data is received, and based on this data, binary image data is expanded on the image memory 52 in step S4. (The image data is developed at a resolution lower than that of the printer unit 33.) Next, in step S5, a scaling factor corresponding to the designated resolution is set in the enlarging / reducing circuit 57. For example, 240 dpi
Image data is expanded with the resolution of 400d
When outputting with a resolution of pi, the scaling factor to be set is (400/240) × 100 = 166.6%. Then, in step S6, the image signal control circuit 32 is passed through the enlargement / reduction circuit 57 set to the above-mentioned scaling ratio.
The image signal is sent to.

As described above, the binary image data expanded at 240 dpi is converted into 400 dpi multi-valued image data, and the printer 33 executes printing.

As described above, according to the second embodiment, since the image data is developed at a resolution lower than the resolution of the printer 33, the processing time of the image data is shortened and the resolution conversion by the multivalued image is performed. Therefore, there is an effect that the deterioration of the output image is reduced.

<Third Embodiment> In a third embodiment, a case will be described in which a known facsimile function is applied to a means for generating binary image data.

As shown in FIG. 9, the normal facsimile function is such that the data received via the public line 37 is transferred by the facsimile image receiving / expanding unit 36 to a memory (not shown) included in the facsimile image receiving / expanding unit 36. Expand the image to. When the resolution of the developed image data is converted and output by the method as described in the first embodiment, the information of the image size and the resolution is required. However, if the facsimile communication function is used, It is possible to know the size of the received image and the resolution of the image. Therefore, it is possible to obtain an appropriate enlargement / reduction ratio from these values and output it as an image of multi-valued data.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device.

[0034]

As described above, according to the present invention, it is possible to generate and output image data of a desired resolution from image data, and to suppress the deterioration of the image quality with a simple structure and reduce the resolution. It is possible to provide an image forming apparatus that executes conversion. In addition, for image data with variable resolution, it is possible to expand the image at a desired resolution and then convert it to a resolution that matches the output device, expand the image at a lower resolution than the output device, and expand the image. It has the effect of shortening the time.

[Brief description of drawings]

FIG. 1 is an overall view of an image forming apparatus according to first and second embodiments.

FIG. 2 is a machine block configuration diagram inside the image forming apparatus.

FIG. 3 is an exposure control signal generation circuit diagram.

FIG. 4 is a signal waveform relationship diagram when an exposure control signal is generated.

FIG. 5 is a block diagram of a binary image generation / storage unit.

FIG. 6 is an explanatory diagram of a scaling algorithm.

FIG. 7 is an explanatory diagram of a resolution conversion algorithm.

FIG. 8 is a flowchart diagram when handling data that does not depend on resolution.

FIG. 9 is a block diagram of an image forming apparatus according to a third embodiment.

[Explanation of symbols]

 30 CPU 31 Image Reader 32 Image Signal Control Circuit 33 Printer Section 34 Binary Image Generation / Storage Section 35 Operation Section 50 CPU 51 Memory Controller 52 Image Memory 53 Input / Output Interface 54 Communication Line 55 Image Data Bus 56 Binary Multi-Value Converter Unit 57 Enlarging / Reducing Circuit

Claims (5)

[Claims] 1. A resolution ratio setting means for setting a ratio between the resolution of input image data and the resolution of multi-valued image data to be output, and the ratio set by the resolution ratio setting means and the input image data. Pixel interpolation means for interpolating and determining the value of each pixel of the output multi-valued image data based on the above, and image data output means for outputting the output multi-valued image data generated by the pixel interpolation means. A characteristic image forming apparatus. 2. A binary multi-value conversion means for converting input binary image data into multi-valued image data, and a resolution of the input binary image data and a resolution of the multi-valued image data to be output. A resolution ratio setting means for setting a ratio, and a value of each pixel of the output multi-valued image data based on the ratio set by the resolution ratio setting means and the multi-valued image data generated by the binary multi-valued conversion means. And an image data output unit for outputting the output multi-valued image data generated by the pixel interpolation unit. 3. A data expansion means for expanding the input image data as binary image data on an image memory, wherein the binary multi-value conversion means converts the binary image data generated by the expansion means. The image forming apparatus according to claim 2, wherein the image forming apparatus converts into multivalued image data. 4. A recording device capable of recording one pixel with multi-valued density, wherein the resolution ratio setting device sets a ratio between input binary image data and a resolution of the recording device, The image forming apparatus according to claim 2, wherein the image data output by the data output unit is recorded by the recording unit. 5. The data expanding means expands binary image data of a specified resolution when the input image data is an image data of a resolution changeable format. The image forming apparatus according to item 4.