IMAGE PROCESSING FOR BINARIZATION OF IMAGE DATA
In order to carry out an image processing with high precision by using a simple structure, an image processing apparatus is provided with an input unit, a storage unit, a binarization unit, and a determination unit. The input unit inputs image data of an image. The storage unit stores a first condition on absolute positions of pixels in the image and a second condition on positions of pixels relative to a target pixel. The binarization unit binarizes the target pixel based upon a color data of the target pixel and that of at least one related pixel to the target pixel to generate a binarized value. The at least one related pixel in the image satisfies the first and second conditions. The determination unit determines whether or not the image has a specified pattern, based upon the binarized values.
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This application is a divisional of application Ser. No. 09/845,349, filed on May 1, 2001, which is based on and claims priority under 35 U.S.C. §119 with respect to Japanese Application Nos. 2000-132465 and 2000-132466 each filed on May 1, 2000. The entire contents of the prior applications is incorporated herein by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to image processing for binarizing image data upon detection of a specified pattern.
2. Description of the Related Art
In recent years, with the developments of functions and performances of color copiers, it becomes possible to obtain a color copy with high quality even by using a commercial scanner, a computer, a color printer and the like. Therefore, it is necessary to provide an effective method for preventing the subsequent counterfeiting acts for paper money, and the like. One of the counterfeiting prevention methods is a technique for inhibiting the generation of an image resembling closely a paper money and the like, upon detection of a specified pattern at the time of copying.
However, an input image is a color image having a great amount of data, and it takes a long time to carry out the corresponding process on the image. From the practical point of view, the process needs to be performed at a high speed, with the result that the processing circuit becomes bulky, complex, and expensive. Moreover, since color hues of the image tend to change depending on scanning conditions, detection of a specified pattern using color discrimination requires a high-performance processing circuit, that is, an expensive circuit.
SUMMARY OF THE INVENTIONAn object of the present invention is to provide an image processing operation with high precision by a simpler construction.
According to the present invention, based upon a color data of a target pixel contained in an image and a color data of at least one related pixel to the target pixel in the image, the target pixel is binarized to generate binarized value. Here, the related pixel satisfies a first condition on absolute positions of pixels and a second condition on positions of pixels relative to the target pixel.
Moreover, in accordance with another aspect of the present invention, a plurality of threshold values are held, and based upon a threshold value selected from these, the target pixel of the image is binarized.
It is an advantage of the present invention that by generating the binarized value in this manner, it is possible to obtain a binarized image that is more properly made by taking into account color information of the peripheral images than that simply binarized by using a single threshold value.
It is another advantage of the present invention that it is possible to obtain a binarized image that is more properly made than that simply binarized by using a single threshold value.
It is a further advantage of the present invention that by using the binarized image obtained through the process of the present invention, it becomes possible to positively determine whether or not a specified image exists in the original image more easily.
These and other object and features of the present invention will become clear from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, in which:
Preferred embodiments of the present invention will be described hereinafter by referring to the accompanying drawings.
Embodiment 1The following description will discuss the computer system 1 that includes a computer serving as an image processing apparatus 100. Not limited to a so-called personal computer, such as a desk-top computer and a lap-top computer, a computer installed in a color copier may be included. The computer system 1 is provided with the image processing apparatus 100, a monitor 2 for displaying an output from the image processing apparatus 100, a keyboard 3 and a mouse 4 used for inputting information to the image processing apparatus 100, a printer 7 for printing images, a scanner 8 for inputting image data to the image processing device 100, a floppy disk drive 5b and a CD (or DVD) drive 9b. Besides these, the means for inputting image data also includes a network interface for receiving image data from another computer 6 and the like, through a network, an interface for inputting image data from a digital camera and the like, for example, an IEEE1394 interface and the like (none of them are shown). Here, in the present embodiment, an explanation will exemplify a computer system. However, this is also applied to a color copier having a built-in image processing apparatus 100.
Next, explanations will be given of the respective components of the above-mentioned image processing apparatus 100. The image input unit 10 is used for inputting image data to the image processing apparatus 100. The image data is composed of a plurality of pixels, each of which has a color data represented by a pixel value. Here, the greater the number of the pixels and the greater the number of colors represented by the color data, the higher the resolution in the corresponding image, while the smaller the number of the pixels, that is, the smaller the number of colors represented by the color data, the lower the resolution therein. The inputted image has a resolution of, for example, 600 dots per inch (dpi), or 300 dpi.
The storage unit 20 is a memory, a hard disk and the like, for storing the inputted image data. The storage unit 20 stores one or more threshold values that are used in association with a binarizing operation in the image processing unit 30 which will be described later, an absolute positional condition for defining absolute positions of pixels in the input image and a relative positional condition for defining a positions of pixels relative to the target pixel, which are used for selecting a relative pixel. Moreover, the storage unit 20 also stores a pixel specifying condition for directly specifying a position from the target pixel. A binarizing operation utilizing the absolute positional condition, the relative positional condition and the pixel specifying condition will be described later in detail.
The image processing unit 30 carries out an image processing on image data containing color data. In other words, the image processing unit 30 carries out processes described in step 302 to 308 in
The printer interface 40 is used in the case when image data is outputted to the printer 7 (
The video interface 50 is used in the case when image data is outputted to the monitor 2 (
With respect to the image processing apparatus 100 (
Referring to
Any of processes (steps 404 to 410) successively carried out by the image processing unit 30 (
According to the present invention, the image processing unit 30 (
The following description will discuss the binarizing operation. First, the image processing section 30 (
Next, among pixels that satisfy an absolute positional condition, a pixel that satisfies a relative positional condition to the target pixel is selected as a relative pixel (step 406). Here, the absolute positional condition is explained as follows. The absolute positional condition is defined as “the condition which, with respect to a predetermined direction within the image, specifies positions of pixels corresponding to every N-th pixel from the pixel on the edge of the image”. More specifically, supposing that the image has a rectangular shape with the longitudinal direction and the lateral direction, “the absolute positional condition” specifies the position of pixels from the pixel on the edge of the image, for example, in the lateral direction of the image (for example, the 3N-numbered pixel from the edge (N: natural number).
The “relative positional condition” is, on the other hand, defined as “a condition that specifies relative positions of pixels to the target pixel”. More specifically, the “relative positional condition” includes the following conditions:
*Condition (1): pixels that include the target pixel and are located on a straight line extending in a predetermined direction defined by the absolute positional condition.
*Condition (2): pixels located within a predetermined range from the target pixel.
The condition (1) is set so as to increase the speed of the process and to reduce the amount of information. In other words, when, upon selecting a relative pixel, both of the pixels in the longitudinal direction and the lateral direction in the image are collated, the amount of information to be held increases, thereby lengthening the processing time. Therefore, this condition is set by taking this point into consideration. In this example, the pixels in the row direction (lateral direction) including the target pixel correspond to this condition, that is, only the pixels on the row b in
Here, a “pixel specifying condition” similar to the “relative positional condition” may be set. The “pixel specifying condition” is used for directly specifying the position from the target pixel in a predetermined direction, and this is set so as to directly select pixels that are likely to be closely related to the target pixel. For example, those pixels corresponding to 3-, 6-, 7- and 9-numbered pixels from the target pixel in the left to right direction, or those pixels corresponding to 1- and 3-numbered pixels from the target pixel, are specified as such. The pixel specifying condition may be set at random.
Next, the image processing unit 30 (
Next, based upon the color data for binarization of the target pixel and the threshold value, the target pixel is binarized (step 410). The color data for binarization of the target pixel is obtained at step 408. The image data of the target pixel is binarized based on whether or not the color data for binarization of the target pixel is located within the range of the threshold value. The above-mentioned processes of steps 404 to 410 are repeatedly executed while the target pixel is successively changed so that the binarizing operation is carried out with respect to all the pixels in the image.
Among the pixels satisfying the absolute positional condition, those pixels satisfying the relative positional condition are selected as the related pixels, and based on the color data thereof, the target pixel is binarized so that it is possible to obtain a binarized image in which a target area is more suitably extracted as compared with a case in which the binarizing operation is carried out by utilizing a single threshold value as a whole. For example, in an attempt to prevent counterfeiting acts of paper money, the specified pattern needs to be detected at the time of printing the paper money in both of the cases of new paper money or discolored paper money after long-time use. Therefore, even in the case when there are discolored portions and non-discolored portions in paper money, since color data of the peripheral pixels serving as the related pixels are utilized, it is possible to carry out a uniform binarizing operation as a whole.
Moreover, since the related pixels are selected by using the pixel specifying condition, it is possible to utilize those pixels that are more likely to relate to the target pixel so as to carry out the binarizing operation.
Embodiment 2In Embodiment 2, an explanation will be given another method for carrying out a binarizing operation. A plurality of threshold values are preliminarily prepared in an image processing apparatus in accordance with the present embodiment. The image processing apparatus selects one of the threshold values based upon a predetermined reference, and applies to the binarizing process. Thus, it is possible to obtain a binarized image in which a specified pattern in the target area is more suitably extracted as compared with a case in which the binarizing operation is carried out by utilizing a single threshold value as a whole.
Here, the image processing apparatus of the present embodiment has the same constituent elements as those explained in the image processing apparatus 100 (
First, an explanation will be given of an image processing apparatus 100 (
The storage unit 20 is a memory, a hard disk and the like, for storing the input image data. The storage unit 20 stores a plurality of threshold values that are used in a binarizing operation in the image processing unit 30.
The image processing unit 30 carries out an image processing on image data. Processes carried out by the image processing unit 30 are described in step 302 to 308 in
The printer interface 40 used in the case when image data is outputted to the printer 7 (
The video interface 50 is used in the case when image data is outputted to the monitor 2 (
Referring to
Any of processes (steps 704 to 710) successively carried out by the image processing unit 30 (
First, the image processing section 30 (
Next, the image processing unit 30 (
Next, the image processing unit 30 (
When the threshold value has been selected, the image processing unit 30 (
As described above, from a plurality of threshold values, one of them is selected based upon a color data of the reference pixel, and the target pixel is binarized; thus, it is possible to obtain a binarized image from which a target area is easily extracted. For example, in an attempt to prevent counterfeiting acts of paper money, the specified pattern needs to be detected at the time of printing the paper money in both of the cases of new paper money or discolored paper money after long-time use. Therefore, even in the case of a stained paper money as a whole that causes a thicker image in density as compared with that of new paper money, since the binarizing operation of the present invention determines a threshold value based upon a parameter such as a density value and the like, it is possible to obtain a binarized image in which a target area is more suitably extracted as compared with a case in which the binarizing operation is carried out by utilizing a single threshold value as a whole. In the case when the reference color of a specified pattern to be detected has a higher density as compared with the peripheral portions, even if the density on the paper face of paper money and the like, is relatively high, the binarizing operation is carried out in a manner so as to positively detect the specified pattern. It is possible to carry out a binarizing operation in a manner so as to easily discriminate a desired area to be extracted.
The foregoing descriptions have discussed Embodiments 1 and 2 of the present invention. In these examples, in accordance with a computer program stored in a ROM (not shown) of the image processing unit 30 (
Moreover, one portion or all the portions of the computer program stored in the ROM (not shown) in the image processing unit 30 (
It will be appreciated by those of ordinary skill in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof.
The presently disclosed embodiment is therefore considered in all respects to be illustrated and not restrictive.
Claims
1. An image processing apparatus comprising:
- an input unit for inputting image data of an image composed of a plurality of pixels, each having a color data;
- a storage unit for storing a plurality of threshold values;
- a binarization unit for selecting one of the threshold values stored in the storage unit, and for binarizing the target pixel of the image based upon the selected threshold value; and
- a determination unit for determining whether or not the image has a specified pattern, based upon the binarized values obtained by said binarization unit.
2. The image processing apparatus according to claim 1, wherein the binarization unit selects one of the plurality of threshold values based upon the color data of at least one related pixel related to the target pixel among the plurality of pixels.
3. The image processing apparatus according to claim 2, wherein a plurality of pixels within a partial area of the image including the target pixel are at least one related pixels.
4. The image processing apparatus according to claim 3, wherein the binarization unit selects one of the plurality of threshold values based upon the greatest color data among color data possessed by the plurality of related pixels within the partial area.
5. The image processing apparatus according to claim 1, wherein the determination unit determines whether or not an image element having a shape similar to the specified pattern exists, based upon the binarized value, and when the image element is determined to exist, finely examines the shape of the image element to determine whether or not the specified pattern exists.
6. A nontransitory recording medium for recording an image processing computer program comprising the steps of:
- inputting image data of an image composed of a plurality of pixels, each having a color data;
- storing a plurality of threshold values;
- selecting one of the threshold values stored, and binarizing the target pixel of the image based upon the selected threshold value; and
- determining whether or not the image has a specified pattern based upon the binarized values obtained.
7. The nontransitory recording medium for recording an image processing computer program according to claim 6, wherein the binarizing step selects one of the plurality of threshold values based upon color data of at least one related pixel related to the target pixel among the plurality of pixels.
8. The nontransitory recording medium for recording an image processing computer program according to claim 7, wherein:
- the related pixel corresponds to a plurality of pixels within a partial area of the image including the target pixel and wherein, in the step of binarizing, one of the plurality of threshold values is selected based upon the greatest color data among color data possessed by a plurality of related pixels within the partial area.
9. An image processing method comprising the steps of;
- inputting image data of an image composed of a plurality of pixels, each having a color data;
- storing a plurality of threshold values;
- selecting one of the threshold values stored, and binarizing the target pixel of the image based upon the selected threshold value; and
- determining whether or not the image has a specified pattern, based upon the binarized values obtained.
Type: Application
Filed: Aug 24, 2010
Publication Date: Dec 23, 2010
Applicant: Minolta Co., Ltd. (Osaka-shi)
Inventor: Hirotomo ISHII (Toyonaka-shi)
Application Number: 12/862,326
International Classification: G06K 9/68 (20060101);