JPH0367873B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Description of the field to which the invention pertains The present invention relates to a method for recording characters and gradation images in an image recording apparatus capable of recording densities of three or more levels.

(2) Explanation of conventional technology Conventionally, there was no method for recording characters and gradation images separately, so when using a recording method that allows gradation expression, even if images can be recorded well, characters are It has the disadvantage that the resolution decreases and blurring occurs, and conversely, when using the binary density recording method, although characters can be recorded clearly, the image deteriorates considerably.

In addition, the area gradation method, which is one of the typical methods of gradation recording, can obtain stable output because it records in binary, but it requires a large matrix to express multiple gradations. shall be. Therefore, when a pattern containing many high-frequency components such as characters is recorded, the quality of the pattern deteriorates significantly.

In addition, the density gradation method, which is another typical gradation recording method, can obtain a resolution equal to that of the recording head, but it is difficult to stably obtain multi-gradation expression depending on the recording medium and environmental conditions. It was extremely difficult.

(3) Purpose of the Invention In order to eliminate these drawbacks, the present invention records the character area in binary density with one dot corresponding to one pixel, and the gradation image area records multiple dots in each pixel of the input image. The gradation is expressed by a dot matrix pattern of 3-level density (white, gray, black) or higher density by associating them with each other.The drawings will be explained in detail below.

(4) Explanation of the structure and operation of the invention Figure 1 is a schematic diagram of the device structure of the present invention.
is a memory for input document images, 2 is a switching circuit for character recording and gradation image recording, 3 is a control circuit,
4 is a character recording pattern generation circuit, 5 is a gradation recording pattern generation circuit, and 6 is an output buffer memory.

In the operation of this apparatus, first, an image of a document to be recorded is input into the memory 1. In order to output this document image, it is necessary to switch the respective recording modes in the character area and the gradation image area. For this purpose, the switching circuit 2 generates this switching information and provides it to the control circuit 3. The control circuit 3 uses this switching information to allocate each pixel of the image memory 1 to the character recording pattern generation circuit 4 or the gradation recording pattern generation circuit 5. Circuit 4 generates a binary (black, white) pattern for character recording corresponding to one pixel, and circuit 5 generates a 3-value pattern corresponding to the density of the pixel.
A dot matrix pattern consisting of value densities (black, gray, white) is generated, stored in the output line buffer 6, and recorded for each appropriate line.

FIG. 2 shows an embodiment of the present invention, and reference numbers 1 to 6 in the figure are the same as those in FIG. 7 is a document image input device, 8 is a character area/gradation image area segmentation circuit, 9 is a character area coordinate storage memory, and 10 is an address for reading pixels from memory 1.
11 is a buffer memory for the density information of the pixel read out from memory 1; 12 is a circuit for determining whether the pixel to be read belongs to a character area or a gradation image area; 13 is a comparator; and 14 is black. 15 is a white density storage memory, 16 is a dot matrix pattern generation management circuit, 17 is a dot matrix pattern generation circuit, and 18 is a recording line head.

In the operation of the present apparatus, first, a document image is stored in the memory 1 using the input device 7. For this document image,
The cutting circuit 8 separates the character area and the gradation image area, and stores the coordinate information in the memory 9. Here, the memory 9 stores two-dimensional coordinates of character areas as shown in FIG.

To record an input document image, address register 10 reads each pixel from memory 1 in turn into buffer 11 . A determination circuit 12 determines whether or not the read pixel belongs to a character area using information in the memory 9. If the pixel belongs to the character area, the comparator 13 is activated and the density of the pixel read into the buffer 11 is compared with the threshold value. Depending on the result, the contents of either the memory 14 storing the black value or the memory 15 storing the white value are read,
Stored in line buffer 6.

When the determination circuit 12 determines that the pixel read out to the buffer 11 belongs to the gradation image area, the determination circuit 12 activates the dot matrix pattern generation management circuit 16. The circuit 16 controls the timing of generation of dot patterns for tone recording. That is, the pattern generation circuit 17 generates the dot matrix pattern shown in FIG. 4 in accordance with the density information of the pixel read out to the buffer 11. ,black)
, and has a size of 2×2, 4×4, etc., so the resolution is 1/2, 1/4, etc., and it is necessary to determine pixels with corresponding densities. When the pixel read by the address register 10 is determined by the circuit 6 to be a pixel to which a dot pattern is to be associated, the pattern generating circuit 17 generates a dot pattern shown in FIG. 4 according to the density, Store in buffer 6. When the circuit 16 determines that the pixel does not need to be associated with a dot pattern, the address register 10 is incremented by one and the next pixel in the memory 1 is read out.

After the pattern has been stored in the buffer 6 in the manner described above, the buffer information is sent to the recording line head 18 for recording. After recording is completed, the first pixel of the next line that has not yet been recorded is read out from the memory 1, and the same processing is performed.

In the embodiments described above, recording is performed using 3-level densities, but it is obvious that the same effect can be achieved by using a dot matrix pattern with 3-level or higher densities.

(5) Explanation of Effects As explained above, the present invention applies binary values (white, white,
The device has a device configuration that generates dots (black) in accordance with the density, and for gradation image areas, a dot matrix pattern consisting of three or more gradation values for each pixel density. The character area has the advantage of being able to record finely, and the gradation image area having the advantage of being able to stably record multiple densities.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the configuration of the apparatus of the present invention, Fig. 2 is a configuration diagram of the apparatus according to the embodiment of the invention, Fig. 3 is an explanatory diagram showing an example of region segmentation of a document image, and Fig. 4 is a diagram from ternary density. FIG. 3 is a diagram of a dot pattern for gradation recording. In the figure, 1 is a document image memory for input, 2 is a switching circuit for character recording and gradation image recording, 3 is a control circuit, 4 is a pattern generation circuit for character recording,
Reference numeral 5 indicates a pattern generation circuit for tone recording, and reference numeral 6 indicates an output buffer memory.

Claims (1)

[Claims] 1. In a character and gradation image recording device that forms characters and images using dots and is capable of recording densities of three or more values, a switching circuit that switches the method for recording characters and images according to input information, and an input If the information is a character, one pixel corresponds to one dot, and if the input information is an image, one pixel corresponds to a plurality of dots; A character and gradation image recording apparatus comprising: a gradation recording pattern generation circuit that generates a dot matrix pattern with densities of three or more values to express gradations.