JP2897351B2 - Marker removal device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a marker removing device, and more particularly to a marker removing device configured to remove a marker written on a document.

(Prior Art) Conventionally, an image processing of a copier, a facsimile, or the like, which can designate an arbitrary area on a document, detect the area, and easily perform a predetermined image editing in real time without cutting and pasting the document. A device is needed.

Currently, as an image processing device that responds to such demands,
2. Description of the Related Art An image processing apparatus has been put into practical use in which an arbitrary area on a document is designated by a marker pen having a predetermined density to perform desired image editing. This image processing apparatus corresponds to a binary output printer, and recognizes a marker specified by the marker pen as gray in a predetermined density area.

When the image processing apparatus starts operation, it detects a marker on a document, detects whether the document information is outside the marker, on the marker, or in a closed area by the marker, and performs image editing based on the result, and Output as a value image signal.

This type of image processing apparatus removes a marker by setting a threshold (threshold level) for binarizing an image signal between the upper limit of the gray level of the marker and the black level, thereby removing the marker. Are prevented from appearing in the binary image output signal. When this process is performed, only the marker is removed from the document information portion where the marker is overcoated, and the background image of the document is output as it is, so that a high-quality binary image signal output can be obtained. .

(Problems to be Solved by the Invention) However, in the above-described conventional marker removing apparatus, the threshold value for binarizing the image signal must be set between the upper limit of the gray level of the marker and the black level. In addition, there is a problem that even if there is an optimum level below the upper limit of the gray level, the value cannot be set.

Further, the conventional marker removing apparatus is compatible with a binary output printer, and has a problem that it cannot be used in a printer which has recently been put to practical use and which can output multi-values.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned problems of the conventional apparatus, to set a threshold value for binarizing an image signal to an arbitrary value, and to remove a marker which can be used in a printer capable of multi-value output. It is to provide a device.

(Means and Actions for Solving the Problems) In order to achieve the above object, the present invention provides a method for comparing an area recognition circuit for detecting that a marker is on a marker with an image input signal and an upper limit of a gray level of the marker. The comparator, and, from the outputs of the area recognition circuit and the comparator, remove the image input signal when on the marker and the image input signal is equal to or less than the upper limit, and the image input signal is higher than the upper limit. A feature that does not remove the image input signal when it is large.

According to the present invention, the area recognition circuit detects that the image is on a marker, and the comparator detects the magnitude of the image input signal and the upper limit of the gray level of the marker. Then, when the image is on the marker and the image input signal is equal to or less than the upper limit of the gray level of the marker, the image input signal is removed, and when it is larger, the image input signal is not removed.

As a result, for example, a white image output signal is obtained where a marker is not placed on the character information, and character information is obtained where the marker and the character information overlap.

According to the invention of claim (2), a background color image output signal can be obtained where the character information and the marker do not overlap.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a circuit diagram of one embodiment of the present invention. FIG. 2 is a diagram showing an example of information written on a document and its density.

In FIG. 2, when the density on the dotted line 10 in the main scanning direction on the document information “ABC” is represented by a density diagram, the density on the character “ABC” becomes black and Is gray. The level b in the figure is the upper limit of the gray level of the marker.

In FIG. 1, 1 is an area recognition circuit, 2 is a comparator, 3
Is a NAND gate, and 4 is an AND gate, and these constitute a marker removing device. Reference numeral 5 denotes a comparator, which constitutes a binarizing circuit for converting a multi-level output into a binary output.

The area recognition circuit 1 detects the marker 11 from the image input signal a.
For example, a first comparator having a threshold value larger than the upper limit value b of the gray level, a second comparator having a threshold value smaller than the upper limit value b, ,
And a gate for performing an AND operation on the outputs of the two comparators.

When detecting a marker from the image input signal a, the area recognizing circuit 1 outputs an H (high) level signal while detecting the marker, and outputs an L (low) level signal when the marker detection is completed. I do. Therefore, the area recognizing circuit 1 outputs the H-level marker signal c only above the marker.

The comparator 2 compares the image input signal a input to the A terminal with the upper limit value b of the gray level of the marker input to the B terminal, and outputs an H level signal when b ≧ a.
When the input f at the terminal A is larger than the input g at the terminal B (when A> B), the comparator 5 outputs an H-level signal h.

Next, the operation of the circuit of FIG. 1 will be described with reference to the waveform diagram of FIG.

Now, multi-valued (6 bits) as shown in FIG.
Is input to the area recognizing circuit 1, the area recognizing circuit 1 outputs an on-marker signal c. The signal c on the marker enters one input terminal of the NAND gate 3.

The image input signal a is input to the A terminal of the comparator 2, and the upper limit value b of the gray level of the marker is input to the B terminal.
Is applied, the comparator 2 outputs a signal d which becomes H level when the image input signal a is smaller than the upper limit value b.

When the signals c and d are input to the NAND gate 3, NA
From the ND gate 3, an L-level signal e is output only on the marker. This signal is input to one terminal of the AND gate 4.

On the other hand, since the image input signal a is input to the other terminal of the AND gate 4, the image signal f from which the marker has been removed is output from the AND gate 4.

This image signal f is input to one terminal A of the comparator 5. Since a threshold value g for binarizing the image signal is applied to the other terminal B of the comparator 5,
Can obtain an image signal h obtained by binarizing the multilevel signal.

As described above, according to the present embodiment, the marker can be removed from the image input signal a. Further, the threshold value g for binarization can be freely set without being limited to the size between the upper limit value of the gray level of the marker and the black level unlike the conventional device. Therefore, the image input signal a
Can be used, and a good quality binarized image signal can be obtained.

An L level image output signal is obtained where the marker is provided on a white background, and an H level signal is obtained where the marker overlaps the document information.

Next, a second embodiment of the present invention will be described with reference to FIG.

This embodiment is different from the first embodiment only in that the AND gate 4 of the first embodiment is replaced by a multiplexer 7 having a terminal i to which a background level signal i is applied, and other configurations are the same. Note that the same reference numerals in FIG. 4 as those in FIG. 1 indicate the same or equivalent.

The multiplexer 7 selects the A terminal when an L level signal is input to the selection terminal S, and selects the B terminal when an H level signal is input.

Therefore, according to the present embodiment, after the marker is removed from the image input signal a, the signal i of the predetermined background level is replaced. For this reason, even in a document whose background is light gray or the like, it is possible to replace the background color such as light gray instead of white after removing the marker,
A natural image output signal without a sense of discomfort can be obtained.

(Effects of the Invention) As described above, according to the present invention, there is an effect that a marker can be removed from a multi-valued image input signal.

Further, the threshold value for binarizing the multi-valued image signal from which the marker has been removed is not limited to the magnitude between the upper limit of the gray level of the marker and the black level as in the conventional apparatus, and can be freely set. Since it can be set, a high-quality binary image output signal can be obtained.

Further, when the marker removing device of the present invention is connected to a multi-value printer, a multi-value image from which the marker has been removed can be printed out.

Further, when the background density is replaced after the removed marker, a natural image output signal can be obtained even for original information having a background.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention, FIG. 2 is a diagram showing a concentration level of a marker, FIG. 3 is a waveform diagram of signals of main parts of FIG. 1, and FIG. FIG. 9 is a circuit diagram of a second embodiment. 1 ... Area recognition circuit, 2,5 ... Comparator, 3 ... NAND gate, 4
... AND gate, 7 ... Multiplexer

Claims (2)

(57) [Claims] 1. A marker removing device for removing a marker from a multi-valued image input signal, comprising: an area recognition circuit for detecting that the image is on a marker; and an upper limit of the gray level of the image input signal and the marker. A comparator for comparing a value with an output of the area recognition circuit and the comparator, when the image input signal is on a marker and the image input signal is equal to or less than the upper limit, the image input signal is removed, and the image input signal is Means for not removing the image input signal when the value is larger than the upper limit value. 2. A marker removing apparatus for removing a marker from a multi-valued image input signal, comprising: an area recognizing circuit for detecting that the image is on a marker; and an upper limit of the gray level of the image input signal and the marker. A comparator for comparing a value with an output of the area recognition circuit and the comparator, and outputting a background signal instead of the image input signal when the image input signal is on the marker and the image input signal is equal to or less than the upper limit value. Means for not removing the image input signal when the image input signal is larger than the upper limit value.