JP2016063369A - Image processing device, image processing method, image formation device, image processing program, and recording medium thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing device, a processing method, a formation device, and a processing program that prevent an object at a peripheral edge part of an image from sticking out of a printing range.SOLUTION: An image formation device comprises a thinning-out processing unit 23 which detects an edge value indicating strength of an edge component of each pixel of image data, and thins out pixels in such a path that a total of edge values is minimum among paths of pixels connecting one end to the other end of an image so as to convert a longitudinal/lateral ratio of the image.EFFECT: The longitudinal/lateral ratio of the image can be converted while an apparent feeling of incompatibility is suppressed by thinning out pixels of a region where the intensity of an edge component is low, thereby preventing an object at a peripheral edge part of the image form sticking out of a printing range.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image processing apparatus and an image processing method for converting the image size of photographic image data in accordance with the size of output paper when an image corresponding to photographic image data is printed on output paper.

  2. Description of the Related Art Conventionally, when printing a photographic image on output paper, a technique is known in which the size of photographic image data is converted according to the size of the output paper and printing is performed.

  For example, in Patent Document 1, the image data of a document acquired by an image scanner is enlarged so that the image of the document is slightly larger than the output paper, and an image corresponding to the enlarged image data is printed on the output paper. A technique for printing a four-edge-free image having no margin areas on the four surrounding sides is disclosed.

International Publication No. WO2003-26277 (published March 27, 2003) JP 7-311833 A (published on November 28, 1995) JP 2012-128521 A (published July 5, 2012) JP 2010-231648 A (released on October 14, 2010)

  However, in the technique disclosed in Patent Document 1, since image data is enlarged and printed larger than the output paper, there is a problem that the peripheral portion of the image data is cut without being printed on the output paper.

  Thus, for example, as shown in FIG. 12A, when the aspect ratio of the image data and the aspect ratio of the output paper are equal, the area to be cut is relatively small, and the problem that the peripheral object is missing is compared. As shown in FIG. 12B, when the aspect ratio of the image data and the aspect ratio of the output paper are different as shown in FIG. The problem of missing objects tends to occur.

  SUMMARY An advantage of some aspects of the invention is that an object included in an image is printed in an image processing apparatus that converts an image size of image data to be printed according to the size of output paper. It is to prevent it from going out of range.

  An image processing apparatus according to an aspect of the present invention is an image processing apparatus that converts an aspect ratio of an image in image data in accordance with an aspect ratio of an output sheet on which the image is printed. By detecting an edge value indicating the strength of the edge component and thinning out pixels on the path where the total value of the edge values is the smallest among the paths of the pixels connecting the one end to the other end of the image. A thinning-out processing unit for converting the aspect ratio of the image is provided.

  According to the above configuration, the aspect ratio of the image can be converted while suppressing a sense of strangeness of appearance by thinning out pixels in a region where the intensity of the edge component is low. Further, it is possible to prevent the object at the peripheral edge of the image from protruding from the printing range.

1 is an explanatory diagram illustrating a schematic configuration of an image forming apparatus according to a first embodiment of the present invention. 3 is a flowchart illustrating a process flow in an aspect ratio conversion unit provided in the image forming apparatus illustrated in FIG. 1. (A) to (c) is an explanatory diagram showing an example of a process for determining whether or not a face area pixel is performed in the aspect ratio conversion unit of FIG. It is explanatory drawing which shows an example of the edge extraction filter used in the aspect ratio conversion part of FIG. (A)-(i) is explanatory drawing which shows the method of the thinning process performed in the aspect ratio conversion part of FIG. 2, and has shown the example when a person's face is not contained in the image. (A)-(i) is explanatory drawing which shows the method of the thinning process performed in the aspect ratio conversion part of FIG. 2, and has shown the example in case a person's face is contained in the image. It is explanatory drawing which shows schematic structure of the image forming apparatus concerning Embodiment 2 of this invention. It is a flowchart which shows the flow of a process in the aspect ratio conversion part with which the image forming apparatus shown in FIG. 7 is equipped. (A) And (b) is explanatory drawing which shows an example of the extraction process of the character area performed by the aspect ratio conversion part of FIG. It is explanatory drawing which shows schematic structure of the image forming apparatus concerning Embodiment 3 of this invention. 11 is a flowchart showing a flow of processing in an aspect ratio conversion unit provided in the image forming apparatus shown in FIG. (A) And (b) is explanatory drawing which shows the process in the case of performing borderless printing in a prior art.

Embodiment 1
An embodiment of the present invention will be described.

(1-1. Overview of Image Forming Apparatus 1)
In the present embodiment, the present invention is applied to the image forming apparatus 1 that is a digital color multifunction peripheral that executes a mode selected from the copier mode, the print mode, the facsimile transmission mode, the facsimile reception mode, and the image transmission mode. An example will be described. However, the application target of the present invention is not limited to this, and any image processing apparatus that converts the size of photographic image data according to the size of the output paper and an apparatus including the same can be applied.

  The copier mode (copy mode) is a mode for reading image data (reading a document to generate image data) and printing an image of the image data on a sheet. The print mode is a mode in which an image of image data sent from a computer connected to the image forming apparatus is printed on paper. The facsimile transmission mode includes a normal facsimile mode in which image data obtained by reading a document is transmitted to an external device via a telephone line, and an Internet facsimile mode in which the image data is attached to a mail and transmitted over the Internet. The facsimile reception mode is a mode in which image data is received from an external device by facsimile and an image of the received image data is printed on a sheet. The image transmission mode includes (1) a mode in which image data generated by reading a document is attached to an e-mail and transmitted to a specified address (scan to e-mail mode), and (2) generated by reading the document. A mode in which image data is transmitted to a folder designated by the user (scan to ftp mode), and (3) a mode in which image data generated by reading a document is transmitted to a USB memory mounted on the image forming apparatus (scan to usb mode).

  In the image forming apparatus 1, when the copier mode / print mode is selected, the user can select either a monochrome mode for outputting a monochrome image or a full color mode for outputting a full color image. Yes.

(1-2. Overall Configuration of Image Forming Apparatus 1)
FIG. 1 is an explanatory diagram illustrating a schematic configuration of an image forming apparatus 1 according to the present embodiment. As shown in this figure, the image forming apparatus 1 includes an image input device 2, an image processing device 3, a RIP (Raster Image Processor) 4, an image output device 5, a receiving device 6, a transmitting device 7, a storage device 8, and a control. Part 9 is provided.

  The image input device 2 is an image reading unit that reads a document and generates image data in the copier mode, the facsimile transmission mode, and the image transmission mode. More specifically, the image input device has a scanner unit equipped with a CCD (Charge Coupled Device), and converts the light reflected from the original into an electrical signal (analog image signal) that is color-separated into RGB. The electric signal is converted and output to the image processing apparatus 3.

  Note that the image input apparatus 2 reads a document image in full color regardless of whether the full color mode or the monochrome mode is selected.

  The image processing apparatus 3 is an integrated circuit that performs image processing on image data (image signal), and includes an ASIC (Application Specific Integrated Circuit).

  As shown in FIG. 1, the image processing apparatus 3 includes an A / D (analog / digital) conversion unit 11, a shading correction unit 12, an input processing unit 13, a document type determination unit 14, a compression unit 15, and a region separation processing unit. 16, region separation signal compression unit 17, region separation signal decoding unit 18, decoding unit 19, aspect ratio comparison unit 20, face detection unit 21, group photograph determination unit 22, thinning processing unit 23, image quality adjustment unit 24, color correction / Each block includes a black generation unit 25, a filter processing unit 26, and a halftone generation unit 27. The processing contents of these blocks will be described later.

  The image processing device 3 performs image processing on the image data sent from the image input device 2 in the copier mode, facsimile transmission mode, and image transmission mode, and performs image processing on the image data sent from the RIP 4 in the print mode. In the facsimile reception mode, the receiving device 6 performs image processing on the image data received from the external device.

  The image processing apparatus 3 transmits image data subjected to image processing to the image output apparatus 5 in the copier mode, print mode, and facsimile reception mode, and transmits the image data subjected to image processing to the transmission apparatus 7 in the facsimile transmission mode. Send.

  The image processing apparatus 3 transmits image data subjected to image processing to a mail processing unit (not shown) in the scan to e-mail mode of the image transmission mode, and image data subjected to image processing in the scan to ftp mode. Is transmitted to a predetermined folder, and image data subjected to image processing is transmitted to a predetermined USB memory in the scan to usb mode.

  The RIP 4 interprets PDL (Page Description Language) data sent from a printer driver (not shown) according to the PDL language specification, converts the data into continuous tone bitmap image data composed of RGB signals, and generates RGB signals. Is transmitted to the aspect ratio comparison unit 20.

  The image output device 5 prints (forms) an image of the image data sent from the image processing device 3 on a recording medium (for example, paper). As the image output device 5, for example, an electrophotographic or inkjet color printer, a sublimation printer, or the like can be used. Note that “printing” in the present embodiment means any one of printing in the print mode, printing in the copier mode, and printing in the facsimile reception mode.

  The receiving device 6 is connected to a telephone line or the Internet, and receives image data from an external device.

  The transmission device 7 is connected to a telephone line or the Internet, and transmits image data acquired by the image input device 2 and processed by the image processing device 3 to an external device.

  The storage device 8 is storage means for temporarily storing image data handled by the image processing device 3. The configuration of the storage device 8 is not particularly limited, and for example, a hard disk can be used.

  The control unit 9 is a computer including a processor such as a CPU (Central Processing Unit) or a DSP (Digital Signal Processor), and controls the operation of each hardware provided in the image forming apparatus 1. The control unit 9 also has a function of controlling data transfer between the respective hardware provided in the image forming apparatus 1.

(1-3. Configuration of Image Processing Device 3)
As described above, the image processing apparatus 3 includes the A / D (analog / digital) conversion unit 11, the shading correction unit 12, the input processing unit 13, the document type determination unit 14, the compression unit 15, the region separation processing unit 16, and the region. Each block of the separated signal compression unit 17, the region separated signal decoding unit 18, the decoding unit 19, the aspect ratio adjustment unit 28a, the image quality adjustment unit 24, the color correction / black generation unit 25, the filter processing unit 26, and the halftone generation unit 27 It has. The aspect ratio adjustment unit 28 a includes an aspect ratio comparison unit 20, a face detection unit 21, a group photo determination unit 22, and a thinning processing unit 23.

  The A / D converter 11 converts the color image signal (RGB analog signal) sent from the image input device 2 into digital image data (RGB digital signal).

  The shading correction unit 12 performs processing for removing various distortions generated in the illumination system, the imaging system, and the imaging system of the image input device 2 on the image data sent from the A / D conversion unit 11.

  The input processing unit 13 performs gradation conversion processing such as γ correction processing on each of the RGB image data sent from the shading correction unit 12.

  The document type determination unit 14 determines the type of the document read by the image input device 2 based on the RGB image data (RGB density signal) that has been subjected to processing such as γ correction by the input processing unit 13. . Here, as the type of document to be determined, there are a character document, a printed photograph document, a character printed photograph document in which characters and a printed photograph are mixed, and the like. In addition, the document type determination unit 14 determines whether the read document is a color document or a monochrome document based on the image data, and whether it is a blank document or an automatic color determination process (ACS: Auto Color Selection). Whether or not it is a plain document is also determined.

  The compression unit 15 encodes the image data (RGB signal) sent from the document type determination unit 14 and stores it in the storage device 8. Note that the encoding is performed based on, for example, a JPEG (Joint Photographic Experts Group) system.

  Based on the RGB image data sent from the document type determination unit 14, the region separation processing unit 16 determines for each pixel of the input image what image region the pixel is classified into. A region separation signal indicating the discrimination result is generated. Here, the image regions discriminated by the region separation processing unit 16 include a black character region, a color character region, and a halftone dot region. Note that the region separation processing may be in a form in which the image region is determined for each block including a plurality of pixels, instead of determining the image region for each pixel.

  The region separation signal compression unit 17 performs a compression process on the region separation signal generated for each pixel to generate a region separation signal code, and stores it in the storage device 8 in association with each pixel of the image data. Note that the compression processing in the region separation signal compression unit 17 is performed based on, for example, the MMR (Modified Modified Reed) method or the MR (Modified Reed) method, which is a lossless compression method.

  The region separation signal decoding unit 18 performs a decoding process on the region separation signal code generated by the region separation signal compression unit 17. The decoded region separation signal is delivered to the color correction / black generation unit 25, the filter processing unit 26, and the halftone generation unit 27. As a result, the color correction / black generation unit 25, the filter processing unit 26, and the halftone generation unit 27 switch the image processing content according to the type of the image area.

  The decoding unit 19 decompresses the encoded code into RGB image data by performing a decoding process on the encoded code encoded by the compressing unit 15.

  The aspect ratio adjustment unit 28a performs thinning processing to match the aspect ratio of the image of the image data to be printed with the aspect ratio of the output paper when the user selects borderless printing and selects the thinning processing mode.

  In other words, in the present embodiment, when a photo print process is performed using the image forming apparatus 1, the user can select borderless printing or bordered printing via an operation panel (not shown). Yes. When performing borderless printing, the user can select either (i) the thinning-out processing mode or (ii) the scaling processing mode via an operation panel (not shown). The scaling processing mode is a processing mode used in borderless printing according to the prior art, and a scaling processing unit (not shown) provided in the image processing apparatus 3 makes an image slightly larger than the output paper. The image is scaled and printed so that the peripheral edge of the image protrudes from the printing range, thereby performing borderless printing. Alternatively, in the scaling process mode, the image may be printed after being scaled so that one of the long side or the short side of the image coincides with both ends of the output sheet and the other end fits within the output sheet.

  In addition, the selection of the processing mode may be performed, for example, by displaying an image such as an icon indicating both processing modes on the operation panel and the user selecting a desired mode. Alternatively, preview images for printing in both processing modes may be displayed on the operation panel, respectively, and the user may select a desired mode.

  When the thinning processing mode is selected, the aspect ratio comparison unit 20 compares the aspect ratio of the image with the aspect ratio of the output paper based on the input image data, and the thinning processing unit 23 according to the comparison result. It is determined whether or not to perform the thinning process, and a signal indicating the determination result (decimation necessity determination signal) is transmitted to the thinning processing unit 23.

  When the thinning processing mode is selected, the face detection unit 21 determines whether or not a human face included in the image is included based on the image data input from the aspect ratio comparison unit 20. If it is determined that each pixel is a pixel corresponding to the face (face area pixel) or a pixel other than the face, a signal (face area determination signal) indicating these determination results is generated and thinned out. The data is transmitted to the processing unit 23.

  When the thinning processing mode is selected, the group photo determination unit 22 determines whether the image is a group photo based on the image data input from the face detection unit 21, and a signal indicating the determination result (group) A photo determination signal) is transmitted to the thinning processing unit 23.

  When the thinning processing mode is selected, the thinning processing unit 23 performs thinning processing based on the thinning necessity determination signal input from the aspect ratio comparison unit 20 and the group photo determination signal input from the group photo determination unit 22. It is determined whether or not to perform.

  In addition, when performing the thinning process, the thinning processing unit 23 extracts pixels that are less uncomfortable in appearance even if they are removed from the image based on the image data input from the group photograph determination unit 22, and performs the above processing on the image data. The extracted pixels are thinned out to be converted into an image size corresponding to the aspect ratio of the output paper and output to the image quality adjustment unit 24. At this time, the thinning processing unit 23 excludes pixels determined as face area pixels by the face detection unit 21 from the thinning processing targets.

  Further, the thinning processing unit 23 outputs the RGB image data input from the group photograph determination unit 22 to the image quality adjustment unit 24 as it is when the thinning processing is not performed. When the thinning process is not performed, the marginless printing may not be performed, or the marginless printing in the above-described scaling process mode may be performed. Details of processing in the aspect ratio conversion unit 28a will be described later.

  The image quality adjustment unit 24 detects the background of the RGB image data sent from the thinning processing unit 23 and performs background removal correction. The image quality adjustment unit 24 also adjusts the RGB balance (color adjustment, overall color adjustment such as reddish blue), brightness, and vividness based on setting information input by the user via an operation panel (not shown). Make adjustments.

  The color correction / black generation unit 25 performs color correction processing and black generation processing when the full color mode is selected. The color correction process is a process for converting RGB image data into CMY image data and performing a process for improving color reproducibility on the image data. The color correction process is realized by creating an LUT (lookup table) in which input values (RGB) and output values (CMY) are associated with each other, and looking up the output values from the created LUT. Different LUTs may be used depending on the region separation signal. The black generation process performs black generation for generating black (K) image data from CMY image data, while subtracting the black (K) image data from the original CMY image data to obtain new CMY image data. It is a process to generate. The amount of black (K) to be generated may be a different value depending on the region separation signal. Through the above processing, as shown in FIG. 1, the RGB image data is converted into CMYK four-color image data by the color correction / black generation unit 25.

  The filter processing unit 26 performs spatial filter processing (enhancement processing, smoothing processing, etc.) using a digital filter for each plane on the CMYK image data. In the spatial filter processing, different filter coefficients may be used depending on the region separation signal.

  The halftone generation unit 27 executes tone reproduction processing (halftone generation processing) necessary for printing an image in the image output apparatus 5 using an error diffusion method or a dither method.

(1-4. Aspect ratio conversion process)
Next, the aspect ratio conversion process performed in the aspect ratio conversion unit 28a (the aspect ratio comparison unit 20, the face detection unit 21, the group photograph determination unit 22, and the thinning processing unit 23) will be described.

  FIG. 2 is a flowchart showing the flow of processing in the aspect ratio conversion unit 28a.

  The aspect ratio comparison unit 20 calculates a difference (aspect ratio difference) A between the aspect ratio of the image and the aspect ratio of the output paper in the input RGB image data (S1), and the calculated difference A is within a predetermined range. It is determined whether or not (S2).

  For example, the aspect ratio comparison unit 20 has Y1 pixels in the vertical direction and X1 pixels in the horizontal direction of the input image, and the vertical size of the output paper is Y2 cm and the horizontal size is X2 cm. In this case, the aspect ratio difference A is calculated based on the following equation (1).

  Also, the aspect ratio comparison unit 20 determines that the thinning process is performed when the aspect ratio difference A calculated by the above equation (1) satisfies the condition of T1 ≦ A ≦ T2, and if not, the thinning process is performed. It is determined not to be performed. Note that T1 and T2 are preset threshold values, for example, T1 = 1.01 and T2 = 1.1.

  When it is determined in S2 that the difference A is not within the predetermined range, the aspect ratio comparison unit 20 generates a decimation necessity determination signal indicating “no decimation process” and outputs it to the decimation processing unit 23 (S3). ), The process proceeds to S12 described later.

  On the other hand, if it is determined in S2 that the difference A is within the predetermined range, the aspect ratio comparison unit 20 generates a thinning necessity determination signal indicating that “thinning processing is present” and outputs the signal to the thinning processing unit 23. (S4).

  After the process of S4, the face detection unit 21 determines whether or not a face is included in the image based on the RGB image data input from the aspect ratio comparison unit 20 (S5).

  When it is determined in S5 that the face is not included in the image, the face detection unit 21 proceeds to the process of S7 described later.

  On the other hand, when it is determined in S5 that the image includes a face, the face detection unit 21 determines whether each pixel of the image data is a pixel corresponding to the face (face area pixel) or a pixel other than the face. Determination is made and face area pixels are detected (S6). Thereafter, the face detection unit 21 generates a face area determination signal including identification information for identifying a face area pixel and a pixel other than the face area, and outputs the face area determination signal to the thinning processing unit 23 (S7).

As a method for determining whether or not a face is included in an image, for example, a method disclosed in Patent Document 2 can be used. In this method, it is determined whether or not a face is included in the image by the following processes (1) to (6).
(1) First-order differentiation is performed on the input image signal in the direction from top to bottom on the image, and the first-order differential signal is binarized. In addition, second derivative is performed on the input image signal, and the second derivative signal is binarized.
(2) The logical sum of the binarized primary differential signal and the secondary differential signal is obtained and used as the eye / mouth first candidate signal.
(3) In the first eye / mouth first candidate signal, the area, the center of gravity position, the vertical / horizontal length of the area, and the average / dispersion of the luminance in each area for each area constituting the connected area Let it be a feature signal.
(4) Based on the region feature value signal, the eye-like region and the mouth-like region are determined, and the second eye candidate signal and the second mouth candidate signal are output, respectively.
(5) Select two eye candidate regions from the second eye candidate signal, one mouth candidate region from the second mouth candidate signal, and select all the regions so that they do not overlap. The candidate combinations arranged are examined for all combinations, and face candidate signals are generated.
(6) Based on the position of the center of gravity of the candidate regions for the left and right eyes in the face candidate signal, the region where the face exists is cut out using affine transformation to obtain a face candidate image signal. The face candidate image signal is compared with the face standard pattern to determine whether or not it is a face.

  In addition, as a method for determining whether each pixel is a pixel corresponding to a face (face area pixel) or a pixel other than a face, a human eye extracted in a determination process for determining whether or not a face is included in an image. And a pixel included in a region within a predetermined range including the mouth (for example, a rectangular region obtained by enlarging the circumscribed rectangle of the region including the eyes and the mouth 1.5 times vertically and horizontally) is determined as a face region pixel and is not included in the region A method of determining a pixel as a pixel other than a face is used.

  FIG. 3 is an explanatory diagram showing an example of a process for determining whether or not a face area pixel. First, the face detection unit 21 determines whether or not a person is included in the image by the processes (1) to (6) described above with respect to the input image shown in FIG. When it is determined that a human face is included, the face detection unit 21 detects a circumscribed rectangle of the region including the eyes and the mouth, and a rectangular region obtained by multiplying the detected circumscribed rectangle by 1.5 in length and width (See the broken line part in FIG. 3B). Then, as shown in FIG. 3C, the face detection unit 21 determines the face area using the pixels included in the rectangular area as face area pixels and the pixels outside the rectangular area as pixels other than the face area. Generate a signal.

  Note that the method for determining whether or not a face is included in the image and the method for determining whether or not each pixel is a face pixel are not limited to the methods described above, and other methods may be used.

  After the process of S7, the group photo determination unit 22 determines whether the image is a group photo (S8).

A method for determining whether or not a group photo is used is not particularly limited. For example, a method disclosed in Patent Document 3 can be used. In this method, it is determined whether or not the image is a group photograph by the following processes (a) to (d).
(A) Whether the number of face images present in the image detected by the determination process of whether or not a human face included in the image in the face detection unit 21 is greater than or equal to a predetermined threshold (for example, three people) A subject number determination process is performed to determine whether or not.
(B) If the number of face images is equal to or greater than the threshold value, a line-of-sight determination process is performed to determine the proportion of faces in which the line of sight was detected. If the rate at which the line of sight can be detected is equal to or greater than a threshold (for example, 90%), camera line of sight determination processing is performed to determine whether the line of sight of each face image is facing the camera.

  The detection of the line of sight uses the brightness distribution in the eye part (candidate area of the eye detected by the determination process of whether or not the human face included in the image in the face detection unit 21 is included), and has a predetermined width. The peak brighter than the surroundings is defined as the white eye portion of the subject person. When a white eye part is detected from the eye part, it is determined that the line of sight has been detected.

  Further, the direction of the line of sight of the subject person is detected based on the degree of bias of the black eye part. When the subject person is facing the front, there are two brightness peaks due to the white eye portion, and there is a dark portion due to the black eye portion so as to be sandwiched between the two peaks. When the above feature is extracted, it is determined that the subject person is looking at the camera.

Note that gaze detection and gaze direction detection may be performed simultaneously. When the line-of-sight detection result is less than the threshold value, face area determination processing and face interval determination processing are performed to determine whether the photo is a group photo.
(C) When the ratio of faces facing the camera is a certain value (for example, 70% of the detected line of sight) or when the line-of-sight detection result is less than the threshold, the area of each face image is equal to the area of the face image. A face area determination process is performed to determine whether the ratio is within a certain ratio (for example, ± 30%) as compared with the average value.
(D) If the area of the face image is within a certain ratio, obtain the centroid of each face image, and whether the interval between the centroids is within a certain ratio (for example, ± 30%) compared to the average value. A face interval determination process is performed to determine whether or not. If it is within a certain ratio, it is determined that the input image is a group photo. The processes (c) and (d) use the fact that in the case of a group photo, the size of the extracted face images is almost the same size and at almost the same interval.

  If it is determined in S8 that the photo is a group photo, the group photo determination unit 22 generates a group photo determination signal indicating “no thinning process” and outputs the group photo determination signal to the thinning processing unit 23 (S9). Move on to processing.

  On the other hand, if it is determined in S8 that the photo is not a group photo, the group photo determination unit 22 generates a group photo determination signal indicating that “there is a thinning process” and outputs the group photo determination signal to the thinning processing unit 23 (S10). Move on to processing.

  In S <b> 11, the thinning processing unit 23 determines whether or not to perform the thinning process based on the thinning necessity determination signal input from the aspect ratio comparison unit 20 and the group photo determination signal input from the group photo determination unit 22. (S11). Specifically, when at least one of the thinning necessity determination signal and the group photograph determination signal is a signal indicating “no thinning processing”, the thinning processing unit 23 does not perform the thinning process, When both of the group photograph determination signals are signals indicating “with thinning process”, it is determined that the thinning process is performed.

  If it is determined in S11 that the thinning process is to be performed, the thinning processing unit 23 performs the thinning process on the image data (S12), outputs the processed image data to the image quality adjustment unit 24, and ends the aspect ratio conversion process. Details of the thinning process will be described later.

  When it is determined in S11 that the thinning process is not performed, the thinning processing unit 23 outputs the image data transmitted from the group photograph determination unit 22 to the image quality adjustment unit 24 without performing the thinning process on the image data. The aspect ratio conversion process ends. When the thinning process is not performed, the marginless printing may not be performed, or the marginless printing in the above-described scaling process mode may be performed.

(1-5. Thinning process)
Next, the thinning process (the process of S12 described above) performed in the thinning processing unit 23 will be described in more detail.

  The thinning processing unit 23 excludes face area pixels in the image from the thinning target, and performs thinning processing by detecting pixels having a small edge component among pixels other than the face area. By reducing the size of the image to the vertical or horizontal direction and reducing the image size in the vertical or horizontal direction while reducing the uncomfortable appearance by converting the thinning target to pixels with a small edge component, conversion is performed to match the aspect ratio of the output paper. Can do.

Specifically, the thinning processing unit 23 performs the following processes (A) to (D).
(A) First, the thinning processing unit 23 converts the input image input from the group photograph determination unit 22 into a luminance component image. The conversion to the luminance component image is performed based on “Y = 0.2990 × R + 0.5870 × G + 0.1140 × B”. R, G, and B in the above formula are RGB values (tone values of each color of R, G, and B) of the input image.
(B) Next, the thinning processing unit 23 performs edge extraction processing on the luminance component image to generate an edge image. The edge extraction process is performed by a convolution operation between the pixel value of the luminance component image and the edge extraction filter. FIG. 4 is an explanatory diagram illustrating an example of an edge extraction filter. FIG. 5A shows an example of an edge image generated by this process. 5A shows an example of an edge image derived from the input image when the input image has a size of 5 × 5 pixels. However, the thinning process is input from the group photograph determination unit 22. This is performed collectively for the entire input image. In FIG. 5A, the larger the numerical value (edge component) shown for each pixel in the edge image, the larger the edge component.
(C) Next, the thinning processing unit 23 determines how many lines the horizontal size (or vertical size) of the input image is reduced based on the aspect ratio of the input image and the aspect ratio of the output paper. To do.
(D) When reducing the size in the horizontal direction, the thinning-out processing unit 23 calculates the total value of the edge components in the pixel column that connects the uppermost row and the lowermost row in the edge image in eight neighborhoods (eight connected). The smallest pixel column is obtained, and the pixels constituting the pixel column are thinned out. Then, this process is repeated until the horizontal size of the image reaches a desired size, thereby matching the aspect ratio of the image with that of the output paper. When the size in the vertical direction is reduced, the thinning-out processing unit 23 has the highest total value of the edge components among the pixel columns connecting the leftmost row and the rightmost row in the edge image in the vicinity of 8 (8 connected). A small pixel column is obtained, and pixels constituting the pixel column are thinned out. This process is repeated until the vertical size of the image reaches the desired size.

Next, the process (D) will be described in more detail by taking as an example the case of reducing the size in the horizontal direction based on the edge image shown in FIG. In the following description, an example in which the horizontal size of the image is reduced will be described. However, in the case of reducing the vertical size, the leftmost column and the rightmost column of the image are arranged in 8 neighborhoods. A similar process may be performed on the pixel columns to be connected.
(D1) First, as shown in (a) and (b) of FIG. 5, the thinning processing unit 23 uses the leftmost pixel in the second row of the edge image as a target pixel, and among the eight neighboring pixels with respect to the target pixel, An addition process is performed in which the minimum value is obtained from the upper three pixels and added to the value of the target pixel.
(D2) Similarly, as shown in FIG. 5C, for all the pixels in the second row of the edge image, the minimum value of the upper three pixels among the eight neighboring pixels for each pixel is obtained and added to the target pixel. Addition processing is performed. When the processing for the pixels in the second row is completed, the same processing is performed for the pixels in the third and subsequent rows. FIG. 5D shows a state where the above addition processing has been completed up to the rightmost pixel in the fifth row.
(D3) Next, as shown in FIG. 5E, the thinning-out processing unit 23 obtains the minimum value calculated by the above addition processing for the lowermost row.
(D4) Next, the thinning-out processing unit 23 performs a search process for searching for a pixel having the minimum value among the upper three pixels among the eight neighboring pixels with respect to the pixel having the minimum value. When a pixel having the minimum value is found, that pixel is set as the target pixel, and search processing for searching for the pixel having the minimum value among the upper three pixels among the eight neighboring pixels is similarly performed for the target pixel. This process is repeated until the uppermost line is reached. FIG. 5F shows the result of repeating the search process up to the top line. Pixels colored in gray in (f) of FIG. 5 indicate pixels having the minimum value obtained in each row.
(D4) Further, the thinning processing unit 23 stores the coordinates of the pixels having the minimum value of each row obtained in the search processing, and the original image (group photo determination unit 22 before luminance conversion in (A) above). The pixels corresponding to the stored coordinates are thinned out from the input image input from (1). (G) in FIG. 5 shows an example of the original image corresponding to (a) in FIG. 5, and (h) in FIG. 5 shows each row obtained by the search process in the original image in (g) in FIG. 5 shows an example in which the coordinates of the minimum value are applied, and (i) in FIG. 5 shows the result of thinning out the pixels corresponding to the coordinates of the minimum value with respect to the original image in (g) of FIG. .
(D5) Thereafter, the thinning processing unit 23 determines whether or not the horizontal size of the image has reached a desired size (whether or not the desired aspect ratio has been obtained) by the above-described thinning processing, and has the desired size. If not, the processes (D1) to (D4) are repeated until the desired size is reached.

  In the example shown in FIG. 5, the case where the input image does not include a face image has been described. However, as described above, when the input image includes a face image, the face area pixels are subject to thinning. Exclude from Processing in this case will be described with reference to (a) to (i) of FIG.

  FIG. 6A shows an example of an edge image generated by the process (B) when a face is included in the input image. In FIG. 6, the hatched pixels are face area pixels.

  As shown in (c) of FIG. 6, for face area pixels, the pixel value (edge component) is not calculated by the edge extraction filter process in the process (B). Further, as shown in FIG. 6D, when all the upper three pixels of the eight neighboring pixels of the target pixel are face region pixels, the target pixel is also converted into a face region pixel and the processing is continued. Other processing methods are the same as those described in FIG. Thereby, the thinning process is performed on the pixels other than the face area.

  As described above, in the present embodiment, the thinning processing unit 23 performs thinning processing on pixels with weak edge components, thereby converting the aspect ratio of the image to match the aspect ratio of the output paper. That is, the thinning-out processing unit 23 detects an edge value indicating the intensity of the edge component of each pixel in the image data, and the total value of the edge values among the paths of the pixels connecting from one end to the other end of the image is The aspect ratio of the image is converted by thinning out pixels on the path that is minimized.

  Thereby, it is possible to convert the aspect ratio of the image while suppressing the uncomfortable appearance. Further, it is possible to prevent the object at the peripheral edge of the image from protruding from the printing range.

  In the present embodiment, the face detection unit 21 detects a face region that is an area including a human face image, and the thinning processing unit 23 excludes pixels belonging to the face region from the thinning processing targets.

  Thereby, it is possible to prevent an image having a sense of incongruity due to, for example, the balance of the face of the person or the balance of the expression being lost.

  In this embodiment, the group photo determination unit 22 determines whether the image is a group photo. If the group photo is a group photo, the thinning processing unit 23 does not perform the thinning process.

  As a result, it is possible to prevent an uncomfortable image due to, for example, the balance of each person's face and the balance of expressions included in the group photo being lost.

  Further, in the present embodiment, the aspect ratio comparison unit 20 that detects whether or not the difference between the aspect ratio of the image and the aspect ratio of the output paper is within a predetermined range is provided, and the thinning processing unit 23 determines that the difference is predetermined. If it is not within the range, the thinning process is not performed.

  Thereby, it can be prevented that the number of pixels to be thinned out by the thinning-out process becomes too large and the image becomes uncomfortable.

[Embodiment 2]
Another embodiment of the present invention will be described. For convenience of explanation, members having the same functions as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the first embodiment, the configuration has been described in which the human face area included in the image is excluded from the thinning target. In contrast, in the present embodiment, the area corresponding to the character is excluded from the thinning process target.

  FIG. 7 is an explanatory diagram showing a schematic configuration of the image forming apparatus 1 according to the present embodiment. As shown in this figure, the image forming apparatus 1 according to the present embodiment includes an aspect ratio converting unit 28b instead of the aspect ratio converting unit 28a in the image forming apparatus 1 of the first embodiment. Other configurations are the same as those of the first embodiment.

  As shown in FIG. 7, the aspect ratio conversion unit 28 b includes an aspect ratio comparison unit 20, a character range extraction unit 29, and a thinning processing unit 23.

  FIG. 8 is a flowchart showing the flow of processing in the aspect ratio converter 28b.

  The aspect ratio comparison unit 20 calculates a difference (aspect ratio difference) A between the aspect ratio of the image and the aspect ratio of the output paper in the input RGB image data (S21), and the calculated difference A is within a predetermined range. It is determined whether or not (S22).

  When it is determined in S22 that the difference A is not within the predetermined range, the aspect ratio comparison unit 20 generates a decimation necessity determination signal indicating “no decimation process” and outputs it to the decimation processing unit 23 (S23). ), The process proceeds to S27 described later.

  On the other hand, when it is determined in S22 that the difference A is within the predetermined range, the aspect ratio comparison unit 20 generates a thinning necessity determination signal indicating that “thinning processing is present” and outputs the signal to the thinning processing unit 23. (S24).

  Next, the character range extraction unit 29 detects characters in the image based on the image data input from the aspect ratio comparison unit 20, and sets the pixels in the character rectangular area corresponding to the circumscribed rectangle of the detected characters as character range pixels. (S25). Further, the character range extraction unit 29 generates a character range signal indicating whether each pixel is a character range pixel or a pixel other than the character range pixel, and outputs the character range signal to the thinning processing unit 23 (S26).

  As a character detection method in the character range extraction unit 29, for example, OCR (optical character recognition) processing can be used. Moreover, the method of OCR processing is not specifically limited, A conventionally well-known method can be used. For example, the method disclosed in Patent Document 4 can be used.

  In the method of Patent Document 4, first, the input image is reduced in resolution (for example, 75 dpi) and then converted into binary image data. Then, based on the converted binary image data, as shown in FIG. 9A, adjacent black pixels are extracted, and a rectangle (circumscribed rectangle) surrounding the extracted black pixels is calculated, whereby each character is calculated. Extract regions. Further, a feature amount is extracted from the extracted circumscribed rectangle, and the extracted result is compared with the character feature amount included in the dictionary data prepared in advance to perform character recognition to detect similar characters. At this time, the position of the circumscribed rectangle detected as the character is set as the character position. As a result, the character range extraction unit 29 creates a character range signal in which the pixel corresponding to the circumscribed rectangle detected as the character is a character range pixel, as shown in FIG. Send.

  Thereafter, the thinning processing unit 23 determines whether or not to perform the thinning processing based on the thinning necessity determination signal input from the aspect ratio comparison unit 20 (S27).

  If it is determined in S27 that the thinning process is performed, the thinning processing unit 23 performs the thinning process on the image data (S28), outputs the processed image data to the image quality adjusting unit 24, and ends the aspect ratio conversion process. Note that the thinning processing unit 23 identifies character range pixels based on the character range signal input from the character range extraction unit 29, and performs the thinning process by excluding the character range pixels from the thinning target. As the thinning-out method, the same method as in the first embodiment can be used.

  When it is determined in S27 that the thinning process is not performed, the thinning processing unit 23 outputs the image data transmitted from the character range extraction unit 29 to the image quality adjustment unit 24 without performing the thinning process on the image data. The aspect ratio conversion process ends.

  As described above, in this embodiment, the character range detection unit 29 detects a character region that is a region including a character image, and the thinning processing unit 23 excludes pixels belonging to the character region from the thinning processing targets.

  As a result, it is possible to prevent an unnatural image from being lost due to the imbalance of characters.

[Embodiment 3]
Another embodiment of the present invention will be described. For convenience of explanation, members having the same functions as those of the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the first embodiment, the configuration has been described in which the human face area included in the image is excluded from the thinning target. In the second embodiment, the configuration in which the area corresponding to the character is excluded from the thinning process target has been described. On the other hand, in the present embodiment, the area of the person's face and the area corresponding to the character are excluded from the thinning process targets.

  FIG. 10 is an explanatory diagram showing a schematic configuration of the image forming apparatus 1 according to the present embodiment. As shown in this figure, the image forming apparatus 1 according to the present embodiment includes an aspect ratio converting unit 28c instead of the aspect ratio converting unit 28a in the image forming apparatus 1 of the first embodiment. Other configurations are the same as those of the first embodiment.

  As shown in FIG. 10, the aspect ratio conversion unit 28 c includes an aspect ratio comparison unit 20, a face detection unit 21, a group photograph determination unit 22, a character range extraction unit 29, and a thinning processing unit 23.

  FIG. 11 is a flowchart showing the flow of processing in the aspect ratio converter 28c.

  The process of S1-S10 is the same as that of Embodiment 1 (S1-S10 of FIG. 2).

  After the process of S10, the character range extraction unit 29 detects a character in the image based on the image data input from the aspect ratio comparison unit 20, and determines a pixel of the character rectangular area corresponding to the circumscribed rectangle of the detected character. Extracted as character range pixels (S25). Further, the character range extraction unit 29 generates a character range signal indicating whether each pixel is a character range pixel or a pixel other than the character range pixel, and outputs the character range signal to the thinning processing unit 23 (S26). As a method for extracting a character range pixel, the same method as in the second embodiment can be used.

  Thereafter, the thinning processing unit 23 determines whether or not to perform the thinning process based on the thinning necessity determination signal input from the aspect ratio comparison unit 20 and the group photo determination signal input from the group photo determination unit 22. (S11).

  If it is determined in S11 that the thinning process is to be performed, the thinning processing unit 23 performs the thinning process on the image data (S12), outputs the processed image data to the image quality adjustment unit 24, and ends the aspect ratio conversion process. Details of the thinning process will be described later. When it is determined in S11 that the thinning process is not performed, the thinning processing unit 23 outputs the image data transmitted from the group photograph determination unit 22 to the image quality adjustment unit 24 without performing the thinning process on the image data. The aspect ratio conversion process ends.

  As described above, in the present embodiment, the face detection unit 21 detects a face region that is a region including a human face image, and the character range detection unit 29 detects a character region that is a region including a character image. The thinning processing unit 23 excludes pixels belonging to the face area and pixels belonging to the character area from the thinning process targets.

  As a result, it is possible to prevent the image from having a sense of incongruity due to the loss of the balance of the face of the person or the balance of the characters.

[Embodiment 4]
The control blocks (particularly the image processing device 3, the control unit 9, and the RIP 4) of the image forming apparatus 1 may be realized by a logic circuit (hardware) formed on an integrated circuit (IC chip) or the like, or a CPU ( It may be realized by software using a Central Processing Unit.

  In the latter case, the image processing apparatus 3, the control unit 9, and the RIP 4 have a CPU that executes instructions of a program that is software realizing each function, and the program and various data are recorded so as to be readable by a computer (or CPU). In addition, a ROM (Read Only Memory) or a storage device (these are referred to as “recording media”), a RAM (Random Access Memory) for expanding the program, and the like are provided. And the objective of this invention is achieved when a computer (or CPU) reads the said program from the said recording medium and runs it.

  As the recording medium, a “non-temporary tangible medium” such as a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. The program may be supplied to the computer via an arbitrary transmission medium (such as a communication network or a broadcast wave) that can transmit the program. The present invention can also be realized in the form of a data signal embedded in a carrier wave in which the program is embodied by electronic transmission.

[Summary]
An image processing apparatus 3 according to an aspect 1 of the present invention is an image processing apparatus 3 that converts an aspect ratio of an image in image data in accordance with an aspect ratio of an output sheet on which the image is printed. An edge value indicating the intensity of the edge component of the pixel is detected, and pixels on the path where the total value of the edge values is the minimum among the paths of the pixels connecting the one end to the other end of the image are thinned out. Accordingly, a thinning processing unit 23 for converting the aspect ratio of the image is provided.

  According to the above configuration, the aspect ratio of the image can be converted while suppressing a sense of strangeness of appearance by thinning out pixels in a region where the intensity of the edge component is low. Further, it is possible to prevent the object at the peripheral edge of the image from protruding from the printing range.

  The image processing device 3 according to aspect 2 of the present invention includes the face detection unit 21 that detects a face area that is an area including an image of a person's face based on the image data in the aspect 1, and includes the thinning processing unit. 23 may be configured to exclude pixels belonging to the face area from the thinning target.

  If pixels corresponding to a person's face are thinned out, the balance of the face or the balance of expression may be lost, and the image may appear unnatural. On the other hand, according to the above configuration, the pixels belonging to the face area are excluded from the thinning target, so that an unnatural image can be prevented.

  The image processing device 3 according to the aspect 3 of the present invention includes the character range detection unit 29 that detects a character area that is an area including a character image based on the image data in the aspect 1 or 2, and the thinning process described above. The unit 23 is configured to exclude pixels belonging to the character area from the thinning target.

  If pixels corresponding to a character are thinned out, the balance of the character may be lost, resulting in an unnatural image. On the other hand, according to the above configuration, pixels belonging to the character region are excluded from the thinning target, so that an unnatural image can be prevented.

  The image processing device 3 according to the aspect 4 of the present invention is the assembly according to any one of the above aspects 1 to 3, wherein the image data image is a group photo that includes a predetermined number of human face images. A photo determination unit 22 is provided, and the thinning processing unit 23 is configured not to perform the thinning process when the group photo determination unit 22 determines that the photo is a group photo.

  In the case of a group photo, there are many face areas in the entire image. For this reason, when the thinning process is performed, the pixels in the face area are thinned out, the balance of facial expressions may be lost, and the image may appear unnatural. On the other hand, according to the above configuration, when it is determined that the photo is a group photo, the thinning process is not performed, so that an unnatural image can be prevented.

  The image processing apparatus 3 according to the fifth aspect of the present invention detects whether or not the difference between the aspect ratio of the image and the aspect ratio of the output paper is within a predetermined range in any one of the first to fourth aspects. An aspect ratio comparison unit 20 is provided, and the thinning processing unit 23 is configured not to perform the thinning processing when the difference is not within the predetermined range.

  If the aspect ratio of the image data and the aspect ratio of the output paper are significantly different, the number of pixels to be thinned out will increase, so the image after thinning will be significantly different from the original image, resulting in an unnatural image. May end up. On the other hand, according to the above configuration, since the thinning process is not performed when the difference between the aspect ratio of the image and the aspect ratio of the output paper is not within the predetermined range, an unnatural image is prevented. it can.

  An image forming apparatus 1 according to an aspect 6 of the present invention includes the image processing apparatus 3 according to any one of the above aspects 1 to 5, and an image forming unit 5 that prints an image corresponding to the image data on output paper. It is characterized by that.

  According to the above configuration, it is possible to convert the aspect ratio of the image while suppressing the uncomfortable appearance. Further, it is possible to prevent the object at the peripheral edge of the image from protruding from the printing range.

  An image processing method according to an aspect 7 of the present invention is an image processing method for converting an aspect ratio of an image in image data according to an aspect ratio of an output sheet on which the image is printed, and for each pixel in the image data. Among the steps of detecting the edge value indicating the strength of the edge component and the path of the pixels connecting the one end to the other end of the image, the pixels on the path where the total value of the edge values is minimized are thinned out. And a thinning process step for converting the aspect ratio of the image.

  According to the above method, the aspect ratio of the image can be converted while suppressing a sense of strangeness of appearance by thinning out pixels in a region where the intensity of the edge component is low. In addition, it is possible to prevent the problem that the object at the peripheral portion of the image protrudes from the print range, which is a problem of the configuration in which the conventional image is enlarged and printed to a size larger than the output paper.

  The image processing apparatus 3 according to each aspect of the present invention may be realized by a computer. In this case, an image processing program that causes the image processing apparatus to be realized by a computer by causing the computer to operate as the thinning processing unit. , And a computer-readable recording medium on which it is recorded are also included in the scope of the present invention.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and the embodiments can be obtained by appropriately combining technical means disclosed in different embodiments. The form is also included in the technical scope of the present invention.

  The present invention can be applied to an image processing apparatus and an image processing method for converting the image size of photographic image data according to the size of the output paper when an image corresponding to the photographic image data is printed on the output paper.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image input apparatus 3 Image processing apparatus 4 RIP
DESCRIPTION OF SYMBOLS 5 Image output device 9 Control part 20 Aspect ratio comparison part 21 Face detection part 22 Group photo determination part 23 Thinning process part 28a-28c Aspect ratio adjustment part 29 Character range extraction part

Claims (9)

An image processing apparatus that converts an aspect ratio of an image in image data according to an aspect ratio of an output sheet on which the image is printed,
An edge value indicating the intensity of the edge component of each pixel in the image data is detected, and a path of pixels connecting the one end part to the other end part of the image is on a path where the total value of the edge values is minimized. An image processing apparatus comprising: a thinning processing unit that converts the aspect ratio of the image by thinning pixels. A face detection unit for detecting a face area that is an area including an image of a person's face based on the image data;
The image processing apparatus according to claim 1, wherein the thinning processing unit excludes pixels belonging to the face area from the thinning processing target. A character range detection unit that detects a character region that is a region including a character image based on the image data;
The image processing apparatus according to claim 1, wherein the thinning processing unit excludes pixels belonging to the character area from the thinning processing target. A group photo determination unit for determining whether the image of the image data is a group photo including a predetermined number of human face images;
The image processing apparatus according to claim 1, wherein the thinning processing unit does not perform the thinning processing when the group photo determination unit determines that the group photo is a group photo. . An aspect ratio comparison unit that detects whether or not the difference between the aspect ratio of the image and the aspect ratio of the output paper is within a predetermined range;
5. The image processing apparatus according to claim 1, wherein the thinning processing unit does not perform the thinning processing when the difference is not within the predetermined range. An image processing apparatus according to any one of claims 1 to 5,
An image forming apparatus comprising: an image forming unit that prints an image corresponding to the image data on an output sheet. An image processing method for converting an aspect ratio of an image in image data according to an aspect ratio of an output sheet on which the image is printed,
Detecting an edge value indicating an intensity of an edge component of each pixel in the image data;
A thinning process step of converting the aspect ratio of the image by thinning out pixels on a path where the total value of the edge values is the smallest among the paths of pixels connecting the one end part to the other end part of the image. An image processing method comprising:   An image processing program for causing a computer to function as the image processing apparatus according to claim 1, wherein the computer functions as the thinning processing unit.   A computer-readable recording medium on which the image processing program according to claim 8 is recorded.

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