JPS6030268A - Facsimile equipment - Google Patents

Abstract

PURPOSE:To reduce a part where the density variation of a recording image does not appear and obtain the clear recording image with articulate contrast by varying gradation intervals according to a density distribution when half-tone representation in N gradations is performed. CONSTITUTION:An original such as a document is read by a readout digital conversion part 2 and converted into a digital signal. This digital picture signal is stored temporarily in a picture signal storage part 3 and also applied to a density distribution decision part 4, which decides roughly on the density distribution of the original on the basis of the digital image signal of one page of the original to generate a density decision signal. This density decision signal is supplied to the picture signal storage part 3 and stored together with the digital picture signal. Those signals are transmitted to a reception part 6 through a band-compression modulation and transmission part 5; and the reception part 6 designates gradations closely where the density distribution is one-sided or roughly at other parts according to the density decision signal, and a recording part 8 performs recording.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a facsimile system having an image signal storage section and capable of performing halftone gradation correction.

Conventionally, in a facsimile receiver, in order to express halftones of N gradations, a reception signal linear with respect to the signal density of one image is applied to a recording element to perform one gradation recording. For this reason,
When image information with a biased density distribution is received and recorded, there is a problem in that the recorded image has a recorded portion in which almost no change in density appears, and the contrast of the recorded image is not clear.

An object of the present invention is to set the gradation densely in areas where the density is uneven when performing N gradation halftone expression.

In other words, by changing the gradation interval according to the density distribution, the facsimile machine can reduce the areas where density changes do not appear in the recorded image as described above, and make it possible to produce clear recorded images with clear contrast. It is about providing.

According to the present invention, there is provided a digital conversion means for digitally converting an analog image signal obtained by reading an original according to its gradation, a storage means for storing the digital image signal f output from the digital conversion means, and a digital image signal f for one page of the original. density distribution discrimination means for inputting all digital image signals and outputting a density distribution discrimination signal according to the density distribution of the document; transmission means for transmitting all the density distribution signals together with the image signals stored in the storage means; When a signal transmitted from the means is received, and the density distribution of the document is skewed according to the density distribution signal, both sides are simultaneously ! :9 gradation difference? A facsimile device is provided which includes means for adjusting the energy applied to the recording head so as to maintain the recording head.

Next, embodiments of the present invention will be described with reference to all drawings.

FIG. 1 is a block diagram of a facsimile machine according to the present invention. In the figure, the transmitting section includes a reading digital conversion section 2 that reads an original image and digitizes the image signal, and an image signal comprising a disk or the like. Further, the receiving section 6 includes a demodulation band expansion section 7 and a thermal recording section 8 using a thermal head. First, an original such as a document is read by a reading digital conversion section 2, and the generated image signal is converted into a digital image signal. In this embodiment, it is assumed that the digital converter 2 sets the number of quantization gradations to 16 gradations, converts the image signal into a 5-bit digital image signal, and records 81@sea bream on the receiving side. The digital image signal is stored in the image signal storage section 3. On the other hand, the density distribution determination section 4 roughly determines the density distribution of the original based on the digital image signal for one page of the original, and generates a density determination signal. FIG. 2 is a circuit diagram showing details of the concentration distribution determining section 4. As shown in FIG. In the figure, the comparator 10a detects a 0 degree amber image signal from the 5-bit digital image signal (output signal of the digital converter 2) from the input bus 20, and connects the comparator 10J- to the 5-bit digital image signal from the input bus 20. Detects an image signal with low density among the image signals. That is, the reference level generators 10a and 10b have a high concentration reference level and a low f/l! level, respectively. A standard level of 8 degrees is set, and the comparators 10a, 1
Detection is rejected and a bell is given to 0b. The NOR gate terminal 11 detects all image signals having a relatively small deviation in density distribution, which does not correspond to either high density or low density. counter 1
2al12bl12C are the comparators 10a, respectively.
, NOR gate terminal 11. The number of pixels of the image signal divided for each density distribution detected by the comparator 10b is counted for one page. Input terminal 19a A clock generated for each KU pixel.

A clock generated for each page of the original is input to the input terminal 19b, and the counters 12a to 12G output the comparator 10a, the NOR gate output, and the comparator 10b in synchronization with the clock from the input terminal 19a.
The counting operation is performed completely, and the count is terminated by the tarock from the input terminal 19b, and the contents thereof are output. Comparator 13a is connected to counter 12a and counter 1.
The output of the counter 2b is compared, and when the count output of the counter 12a is large, the output is set as ffHigh. Comparator 1
3b compares the outputs of the counter 12b and the counter 12c, and sets the output to H when the count output of the counter 12b is large.
Let it be igh. The comparator 13C compares the counter 12C and the counter 12af, and when the count output of the counter 12c is large, it is set as II i gh. This is the comparator 13a, 13b.

13C2 and flip 7o7p 18a, 18b.

In L8c, when the concentration distribution is concentrated in a relatively high portion, the AND gate 14a is turned on, the flip-flop 18a'i is set, and the output terminal 15 becomes ``high''. AN when the concentration distribution is relatively unbalanced
D gate 14b is selected.

7 lip 70 tsugu 18b? output terminal 16)
(It becomes ``high.'' Furthermore, when the % concentration distribution is concentrated in a relatively low part, the % AND game) 14G is selected and the flip is 70 to 18C? set, and output terminal 17 is High.
h.

As described above, density determination signals representing the density distribution of the original are output from the output terminals 15, 16, and 17 and supplied to the image signal storage section 3 in FIG. The image signal storage section 3 stores all the density determination signals together with the digital image signal. The image signal band compression modulation transmission section 5 compresses the image information output from the one-image signal storage section 3, modulates it, and sends it to the signal communication line 9.

In the receiving section 6, first, the signal demodulating band expanding section 7 demodulates the modulated signal transmitted from the transmitting section 1, and then expands the band.
All bit digital image signals and density determination signals are reproduced. Recording section lit: Performs 8-gradation recording based on the reproduced 5-pit digital image signal and density determination signal. There is a D/D converter (not shown) inside the recording unit 8, which converts the input image signal from 5 bits to 3 bits, that is, 16 bits.
Convert from gradation to 8 gradation. Concentration distribution determination section 4 in Fig. 2
When the output terminal 15 of the IJ-F/F 18a of the Perform 5/3 bit conversion to make it coarser.

In this case, the relationship between the σ & degree Vk key and the quantization level is expressed as
As shown in the figure. Also, the output terminal 16 of the D-F/F 18b is Hi.
gh, that is, the concentration distribution is relatively loose. J: [5/3 bit conversion is performed so that the density scale yAI becomes linear when the density is small. The relationship between density gradation and quantization level in this case is shown in FIG. Furthermore, when the output terminal 17 of the D F/F 18c is High, that is, when the density distribution is concentrated in a relatively low area, one gradation is specified so that the high density area becomes coarse and the low density area becomes dense. 5/3 bit conversion. FIG. 5 shows the relationship between density gradation and quantization level in this case. As mentioned above, the D/D converter performs 5/3 bit conversion in accordance with the designation from the image signal density distribution judgment unit 4 on the transmitting side, thereby converting the data into the data shown in FIGS. 3, 4, and 5, respectively. Set the application time of the thermal head so that the gradation characteristics as shown are obtained. That is, in each diagram, the application time is set in proportion to the concentration corresponding to the quantization level in accordance with the specification of the concentration distribution. Recording section 8
In addition to the D/D converter, the power application time system circuit (not shown) is built in, and the application time of the recording voltage to the thermal head is set in accordance with the output signal of the D/Df converter.

Note that in the above embodiment, the reading and digital conversion section 2
The output digital image signal was stored as is in the storage section 3, and the output was band-compressed.

The band may be compressed before being stored in the storage unit 3.

Inventiveness 1 As explained above, a facsimile system includes an image signal storage section and a recording section capable of expressing halftones,
By storing digitalized image signals, editing and communication methods are speeded up, and the density distribution of the original is judged using the -manryo signal, and the density gradation is specified for each page of the original according to the judgment result. By setting the uneven distribution densely and the other portions coarsely, the contrast of the recorded area is made clear and the effect of making the recorded area clear is provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a detailed block diagram of a concentration distribution measurement circuit, and FIG. 3 shows the relationship between concentration and quantization level when there is a distribution on the higher concentration side. Figure 4 is a diagram showing the relationship between density and quantization level when the density distribution is less skewed, and Figure 5 is a diagram showing the relationship between density and quantization level when the density distribution is skewed towards the lower side. be. 1... Transmission unit, 2... Reading, digital conversion unit, 3... Image signal storage, 4...
Concentration distribution determination section, ... Image signal band compression modulation transmission section, 6... Receiving section, 7. Demodulation band expansion section,
8... Recording department. Agent Patent Attorney Susumu Uchihara

Claims (1)

[Claims] digital conversion means for digitally converting an analog image signal read from a document according to its gradation; a storage means for storing digital image signal information output from the digital conversion means; and a digital image signal for one page of the document. Input the rlk degree distribution discrimination signal according to the density distribution of the original? density distribution determining means for outputting; transmission means for transmitting the density distribution signal together with the image signal information stored in the storage means; receiving the signal transmitted from the transmission means; and means for adjusting energy applied to the recording head so that when the density distribution of the reproduced image is uneven, a gradation difference is created depending on the density of the reproduced image.