JP2015019192A - Image processing apparatus and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing apparatus and program capable of outputting an image having desired frequency characteristics regardless of output resolution, even when the desired frequency characteristics are different between input images.SOLUTION: An image processing apparatus 2 includes: an image receiving unit 20 that receives an image to which resolution and processing conditions of frequency correction processing applied to the image are added; an output resolution acquisition unit 22 that acquires output resolution; a resolution conversion unit 24 that converts the resolution of the received image into the output resolution; a frequency correction processing determination unit 26 that determines the processing conditions of the frequency correction processing to be applied to the image converted by the resolution conversion unit 24, on the basis of the resolution and output resolution of the received image and the received processing conditions; and a frequency correction processing execution unit 28 that executes the frequency correction processing to the image converted by the resolution conversion unit 24 with the determined processing conditions.

Description

  The present invention relates to an image processing apparatus and a program.

  Patent Document 1 discloses a method for performing frequency processing on image data so as to obtain a certain visual effect regardless of the output resolution of the image. An image processing method for obtaining processed image data capable of reproducing an image having a size, wherein the number of pixels of the image represented by the image data so as to achieve the desired output size at a predetermined reference resolution Is converted to obtain reference resolution image data, the reference resolution image data is subjected to reference frequency processing suitable for the reference resolution to obtain processed reference resolution image data, and the desired resolution is obtained at the desired output resolution. The number of pixels of the processed reference resolution image represented by the processed reference resolution image data is converted so that the output size becomes It discloses an image processing method characterized by obtaining the processed image data.

  In Patent Document 2, as a method of performing frequency processing so that a constant visual effect can be obtained regardless of the output resolution of an image, the processed image data is obtained by performing reference frequency processing that matches the reference resolution on the image data. In the obtained image processing method, when obtaining the processed image data from high-resolution image data having an output resolution higher than the reference resolution, the resolution of the high-resolution image data is converted to have an intermediate resolution equal to or higher than the output resolution. Enlarged image data is obtained, and the enlarged image data is subjected to multiresolution conversion so that the minimum resolution becomes the reference resolution to obtain multiresolution image data, and the reference frequency processing is performed on the minimum resolution multiresolution image data. To obtain processed minimum resolution image data, and the processed minimum resolution image data and the other multiple resolutions. Inverse multi-resolution conversion image data is obtained by performing inverse multi-resolution conversion on the image data, and resolution processing is performed on the inverse multi-resolution conversion image data so as to be the output resolution to obtain the processed image data having the output resolution. An image processing method characterized by the above is disclosed.

JP 2003-281532 A JP 2003-283807 A

  An object of the present invention is to provide an image processing apparatus and a program capable of outputting an image having a desired frequency characteristic regardless of the output resolution even when the desired frequency characteristic is different for each input image. is there.

  According to a first aspect of the present invention, there is provided an image receiving means for receiving an image to which a processing condition and resolution of a frequency correction process applied to an image are added, an output resolution acquiring means for acquiring an output resolution, and the image receiving means. Resolution conversion means for converting the resolution of the image received by the output resolution acquisition means to the output resolution acquired by the output resolution acquisition means, the resolution of the image received by the image reception means and the output resolution acquired by the output resolution acquisition means, Based on the processing conditions received by the image receiving means, processing determining means for determining processing conditions for frequency correction processing applied to the image converted by the resolution converting means, and processing conditions determined by the processing determining means The image processing apparatus includes processing execution means for performing frequency correction processing on the image converted by the resolution conversion means.

  According to a second aspect of the present invention, in the processing determining unit, the processing condition in which the image receiving unit accepts the frequency band of the image corrected by the processing by the processing executing unit with respect to the image received by the image receiving unit. The image processing apparatus according to claim 1, wherein the processing condition is determined so as to correspond to a frequency band of an image to be corrected when the frequency correction processing is performed according to the above.

  According to a third aspect of the present invention, in the processing determining means, the degree of correction by the processing by the processing executing means is a frequency correction according to the processing condition received by the image receiving means for the image received by the image receiving means. The image processing apparatus according to claim 1, wherein the processing condition is determined so as to correspond to a degree of correction when the processing is performed.

  According to a fourth aspect of the present invention, there is provided an image receiving step of receiving an image to which a processing condition and resolution of a frequency correction process to be applied to the image are added, an output resolution acquiring step of acquiring an output resolution, Resolution conversion step for converting the resolution to the acquired output resolution, frequency correction processing applied to the image whose resolution has been converted based on the resolution of the received image, the acquired output resolution, and the received processing conditions Is a program that causes a computer to execute a process determining step for determining the processing conditions and a process performing step for performing frequency correction processing on an image whose resolution has been converted under the determined processing conditions.

  According to the first aspect of the present invention, there is provided an image processing apparatus capable of outputting an image having a desired frequency characteristic regardless of the output resolution even when the desired frequency characteristic is different for each input image. can do.

  According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, an image processing apparatus capable of performing frequency correction processing so that the frequency band to be corrected becomes a desired frequency band is provided. be able to.

  According to the third aspect of the present invention, in addition to the effect of the present invention according to the first or second aspect, an image processing apparatus capable of performing frequency correction processing so that the degree of correction becomes a desired degree is provided. be able to.

  According to the fourth aspect of the present invention, there is provided a program capable of outputting an image having a desired frequency characteristic regardless of the output resolution even when the desired frequency characteristic is different for each input image. Can do.

It is a schematic diagram which shows the hardware constitutions of the image processing apparatus 2 which concerns on embodiment of this invention. It is a block diagram which shows the function structure of the image processing apparatus 2 implement | achieved by executing a control program. It is a schematic diagram showing the frequency band to be emphasized and the degree of enhancement when the input image is subjected to frequency correction processing suitable for the resolution of the input image and then converted to a resolution different from the resolution of the input image and output. , (A) shows an example when an input image with a resolution of 300 dpi is output at 100 dpi, and (b) shows an example when an input image with a resolution of 300 dpi is output at 600 dpi. . It is the schematic diagram which showed the emphasis frequency characteristic at the time of converting the input image into the image of output resolution, and performing the frequency correction process by which the frequency band emphasized by the frequency correction process determination part 26 was adjusted, (a) Shows an example when an input image with a resolution of 300 dpi is output at 100 dpi, and (b) shows an example when an input image with a resolution of 300 dpi is output at 600 dpi. It is the schematic diagram which showed the emphasis frequency characteristic at the time of converting the input image into the image of output resolution, and performing the frequency correction process by which the degree of emphasis by the frequency correction process determination part 26 was adjusted, (a) An example in which an input image with a resolution of 300 dpi is output at 100 dpi is shown, and (b) shows an example in which an input image with a resolution of 300 dpi is output at 600 dpi. FIG. 5 is a schematic diagram showing an enhanced frequency characteristic when an input image is converted into an image of an output resolution and a frequency correction process in which the frequency band emphasized by the frequency correction process determination unit 26 and the degree of enhancement are performed is performed. (A) shows an example when an input image with a resolution of 300 dpi is output at 100 dpi, and (b) shows an example when an input image with a resolution of 300 dpi is output at 600 dpi. It is a flowchart which shows an example of operation | movement of the image processing apparatus 2 concerning this embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing a hardware configuration of an image processing apparatus 2 according to an embodiment of the present invention. As shown in FIG. 1, the image processing apparatus 2 transmits and receives data to and from a CPU 4, a memory 6, a storage device 8 such as a hard disk drive (HDD), and an external device via a network. It has an interface (IF) 10 and an input / output interface (IF) 12 for inputting and outputting data. These components are connected to each other via a control bus 14.

  The CPU 4 executes processing based on a control program stored in the memory 6 or the storage device 8 and controls the operation of the image processing device 2. In the present embodiment, the CPU 4 has been described as reading and executing a control program stored in the memory 6 or the storage device 8, but the program is stored in a storage medium such as a CD-ROM and stored in the CPU 4. It is also possible to provide the program, and it is also possible to provide the program to the CPU 4 via a network.

  An input device such as a keyboard is connected to the input / output IF 12. An output device is connected to the input / output IF 12. As the output device, a display device such as a display device and an image forming device such as a printer may be connected.

  FIG. 2 is a block diagram showing a functional configuration of the image processing apparatus 2 realized by executing the control program.

  As shown in FIG. 2, the image processing apparatus 2 includes an image reception unit 20, an output resolution acquisition unit 22, a resolution conversion unit 24, a frequency correction processing determination unit 26, and a frequency correction processing execution unit 28. ing.

  The image receiving unit 20 receives an input image. In the present embodiment, information indicating the resolution of the input image and information indicating the processing conditions of frequency correction processing applied to the input image at this resolution are added to the input image received by the image receiving unit 20. Yes. Therefore, the image receiving unit 20 of the present embodiment receives the image data of the input image and information added to the image data.

  Here, the frequency correction process is a process of correcting the spatial frequency of the image. In the present embodiment, the frequency correction process is described as a frequency enhancement process such as unsharp masking, but may be a smoothing process.

  The information indicating the processing conditions of the frequency correction processing is information for designating the frequency band to be emphasized and the degree of enhancement. For example, in the filtering processing applied to the input image when outputting at the resolution indicated in the input image. Processing conditions such as filter size and coefficient may be used.

  The output resolution acquisition unit 22 acquires the resolution of the output device when outputting the image on which the frequency correction processing has been performed. The output resolution acquisition unit 22 may acquire from the output device connected to the input / output IF 12, or may store the resolution of each output device in the storage device 8 in advance and read out the output destination resolution. The resolution may be acquired by input by the user.

  The resolution conversion unit 24 converts the resolution of the image received by the image reception unit 20 into the output resolution acquired by the output resolution acquisition unit 22. The resolution converting unit 24 converts the resolution by enlarging or reducing the image received by the image receiving unit 20 so that the resolution becomes the resolution acquired by the output resolution acquiring unit 22. Note that the resolution conversion unit 24 may convert the resolution by a known resolution conversion method.

  The frequency correction processing determination unit 26 determines processing conditions for frequency correction processing to be applied to the image whose resolution is converted by the resolution conversion unit 24. In the present embodiment, the frequency correction process determination unit 26 determines the resolution of the image received by the image reception unit 20 and the output resolution acquired by the output resolution acquisition unit 22 and the processing conditions added to the image received by the image reception unit 20. The processing conditions of the frequency correction processing when outputting with the output resolution acquired by the output resolution acquisition unit 22 are determined based on the information indicating the frequency. Details of the frequency correction process determined by the frequency correction process determination unit 26 will be described later.

  Thus, in the present embodiment, the frequency correction process is performed based on the processing conditions added to the input image. Therefore, even if the desired frequency characteristic differs for each input image, an image having the desired frequency characteristic is generated for each input image with reference to the information added to the input image.

  The frequency correction processing execution unit 28 performs frequency correction processing on the image whose resolution is converted by the resolution conversion unit 24 under the processing conditions determined by the frequency correction processing determination unit 26. In the present embodiment, the frequency enhancement process is performed under the filtering process conditions determined by the frequency correction process determination unit 26. The image that has been subjected to the frequency correction processing by the frequency correction processing execution unit 28 is output to the output device as an output image.

  Next, the frequency correction process determined by the frequency correction process determination unit 26 will be described. First, a comparative example with respect to the present embodiment will be described, and then an example in which the frequency correction processing determined by the frequency correction processing determination unit 26 is performed will be described.

  FIG. 3 shows the frequency band to be emphasized and the degree of enhancement when the input image is subjected to frequency correction processing suitable for the resolution of the input image and then converted into a resolution different from the resolution of the input image and output. FIG. 4A is a schematic diagram illustrating an example of an input image with a resolution of 300 dpi output at 100 dpi, and FIG. 5B is an example of an input image with a resolution of 300 dpi output at 600 dpi. Is shown.

  3 (a) and 3 (b), the graphs in the figure are graphs showing visually recognized enhanced frequency characteristics, and the frequency band emphasized by the frequency enhancement process and the degree of enhancement are shown. It represents a certain gain (enhancement intensity). Further, in the figure, the left graph is a graph showing a desired enhanced frequency characteristic obtained by performing frequency enhancement processing suitable for the resolution of the input image, and the right graph is a graph at the time of output in the output device. It is a graph which shows an emphasis frequency characteristic. In the right graph, a broken line indicates a desired emphasized frequency characteristic represented in the left graph.

  As shown in FIG. 3A, when the output resolution is low compared to the resolution of the input image, the emphasized frequency band at the output is higher than the desired emphasized frequency characteristic. Move to low range. Further, in the frequency characteristics at the time of output, the degree of enhancement is larger than the desired degree of enhancement. This is because the resolution is smaller than the resolution of the input image, so the pixel size is larger, and the visual enhancement is recognized more greatly than when the resolution is low (in the case of the resolution of the input image). It is thought to be for

  In FIG. 3A, the enhancement frequency characteristic at the time of output changes linearly as compared with the enhancement frequency characteristic at the resolution of the input image. This is the number of pixels constituting the image compared to the input image. This is thought to be due to a lack of information due to a decrease in

  Further, as shown in FIG. 3B, when the output resolution is higher than the resolution of the input image, the emphasized frequency characteristic at the output is emphasized as compared with the desired emphasized frequency characteristic. The belt moves to the high range. Further, in the frequency characteristics at the time of output, contrary to the case of FIG. 3A, the degree of enhancement is smaller than the desired degree of enhancement.

  As described above, when frequency enhancement processing suitable for the resolution of the input image is performed on the input image, the desired frequency characteristic cannot be obtained by converting the resolution at the time of output.

Next, the frequency correction process determined by the frequency correction process determination unit 26 will be described.
For example, the frequency correction processing determination unit 26 sets the frequency band of the image to be corrected by the processing by the frequency correction processing execution unit 28 to the input image received by the image receiving unit 20 under the processing conditions added to the input image. The frequency correction process is determined so as to correspond to the frequency band of the image to be corrected when the frequency correction process is performed.

  FIG. 4 is a schematic diagram showing enhanced frequency characteristics when an input image is converted into an image of output resolution and frequency correction processing in which the frequency band emphasized by the frequency correction processing determination unit 26 is adjusted is performed. , (A) shows an example when an input image with a resolution of 300 dpi is output at 100 dpi, and (b) shows an example when an input image with a resolution of 300 dpi is output at 600 dpi. .

  In the example illustrated in FIG. 4, the frequency correction processing determination unit 26 adjusts the frequency band to be emphasized for the processing conditions of the frequency correction processing indicated in the information added to the input image, and the adjusted frequency correction processing is frequency corrected. This is determined as a processing condition for the frequency correction processing performed by the processing execution unit 28.

  As for the adjustment amount, for example, a shift amount of the emphasized frequency band caused by the difference between the resolution of the input image and the output resolution is investigated in advance, and the adjustment amount is determined in advance based on the investigation result.

  When the output resolution is lower than the resolution of the input image, as shown in FIG. 3A, if the frequency correction process is performed under the processing conditions indicated in the information added to the input image, the frequency to be emphasized The band moves to a lower frequency side than the desired frequency band. Therefore, when the output resolution is lower than the resolution of the input image, the frequency correction processing determination unit 26 moves the emphasized frequency band to the high frequency side for the processing conditions indicated in the information added to the input image. Adjust as follows.

  For example, when the processing conditions shown in the information added to the input image include a filter size and a coefficient of enhancement degree, the frequency correction processing determination unit 26, when the output resolution is lower than the resolution of the input image, The processing conditions are determined so as to use a filter having a size smaller than the size of the filter indicated by the added information. For example, when the resolution of the input image is 300 dpi and the output resolution is 100 dpi, it is determined that the processing is performed with the size of the filter indicated by the added information being 1/3.

  On the other hand, when the output resolution is higher than the resolution of the input image, as shown in FIG. 3B, if the frequency correction process is performed under the processing conditions indicated in the information added to the input image, it is emphasized. Frequency band moves to a higher frequency side than the desired frequency band. Therefore, when the output resolution is higher than the resolution of the input image, the frequency correction processing determination unit 26 moves the emphasized frequency band to the low frequency side for the processing conditions indicated in the information added to the input image. Adjust as follows.

  For example, when the processing conditions indicated in the information added to the input image include a filter size and a coefficient of enhancement degree, the frequency correction processing determination unit 26, when the output resolution is higher than the resolution of the input image, The processing condition is determined so as to use a filter having a size larger than the size of the filter indicated by the added information. For example, when the resolution of the input image is 300 dpi and the output resolution is 600 dpi, it is determined to process the filter indicated by the added information by doubling the size.

  In addition, the frequency correction processing determination unit 26 performs the frequency correction processing on the input image received by the image receiving unit 20 with the processing condition added to the input image to the degree of correction by the processing by the frequency correction processing execution unit 28. The frequency correction processing may be determined so as to correspond to the degree of correction when the above is performed.

  FIG. 5 is a schematic diagram showing enhanced frequency characteristics when an input image is converted into an image with an output resolution and frequency correction processing in which the degree of enhancement by the frequency correction processing determination unit 26 is adjusted is performed. (A) shows an example when an input image with a resolution of 300 dpi is output at 100 dpi, and (b) shows an example when an input image with a resolution of 300 dpi is output at 600 dpi.

  In the example illustrated in FIG. 5, the frequency correction processing determination unit 26 adjusts the degree of emphasis on the processing conditions of the frequency correction processing indicated in the information added to the input image, and the adjusted frequency correction processing is performed as the frequency correction processing. This is determined as a processing condition for the frequency correction processing performed by the execution unit 28.

  As for the adjustment amount, for example, a shift amount of the emphasis degree caused by a difference between the resolution of the input image and the output resolution is investigated in advance, and the adjustment amount is determined in advance based on the investigation result.

  When the output resolution is lower than the resolution of the input image, as shown in FIG. 3A, if the frequency correction process is performed under the processing conditions indicated in the information added to the input image, the enhancement degree is It becomes larger than the desired degree of emphasis. Therefore, when the output resolution is lower than the resolution of the input image, the frequency correction processing determination unit 26 adjusts the processing conditions indicated in the information added to the input image so as to weaken the degree of enhancement.

  For example, when the processing conditions shown in the information added to the input image include a filter size and a coefficient of enhancement degree, the frequency correction processing determination unit 26, when the output resolution is lower than the resolution of the input image, The processing condition is determined so as to use a coefficient of enhancement degree smaller than the coefficient of enhancement degree indicated by the added information.

  On the other hand, when the output resolution is higher than the resolution of the input image, as shown in FIG. 3B, if the frequency correction processing is performed under the processing conditions indicated in the information added to the input image, the degree of enhancement However, it becomes smaller than a desired emphasis degree. Therefore, when the output resolution is higher than the resolution of the input image, the frequency correction processing determination unit 26 adjusts the processing conditions indicated in the information added to the input image so as to increase the degree of enhancement.

  For example, when the processing conditions indicated in the information added to the input image include a filter size and a coefficient of enhancement degree, the frequency correction processing determination unit 26, when the output resolution is higher than the resolution of the input image, The processing condition is determined so as to use a coefficient of enhancement degree smaller than the coefficient of enhancement degree indicated by the added information.

  Further, the frequency correction processing determination unit 26 may adjust both the emphasized frequency band and the enhancement degree.

  FIG. 6 is a schematic diagram illustrating an enhanced frequency characteristic when an input image is converted into an image having an output resolution and a frequency correction process in which the frequency band emphasized by the frequency correction process determination unit 26 and the enhancement degree are adjusted is performed. (A) shows an example when an input image with a resolution of 300 dpi is output at 100 dpi, and (b) shows an example when an input image with a resolution of 300 dpi is output at 600 dpi. Show.

Next, the operation of the image processing apparatus 2 will be described.
FIG. 7 is a flowchart showing an example of the operation of the image processing apparatus 2 according to the present embodiment.

  In step 100 (S100), the image receiving unit 20 receives an image to which information about processing conditions for frequency correction processing is added.

  In step 102 (S102), the output resolution acquisition unit 22 acquires the output resolution.

  In step 104 (S104), the resolution conversion unit 24 converts the resolution of the image received in step 100 into the output resolution acquired in step 102.

  In step 106 (S106), the frequency correction processing determination unit 26 determines the processing conditions for the frequency correction processing to be applied to the image whose resolution has been converted in step 104.

  In step 108 (S108), the frequency correction processing execution unit 28 performs the frequency correction processing of the processing conditions determined in step 106 on the image whose resolution is converted in step 104.

  In step 110 (S110), the image subjected to the frequency correction process in step 108 is output. Note that the image may be output via the communication IF 10.

2 Image processing device 20 Image reception unit 22 Output resolution acquisition unit 24 Resolution conversion unit 26 Frequency correction processing determination unit 28 Frequency correction processing execution unit

Claims (4)

Image receiving means for receiving an image to which processing conditions and resolution of frequency correction processing to be applied to the image are added;
Output resolution acquisition means for acquiring output resolution;
Resolution conversion means for converting the resolution of the image received by the image reception means into the output resolution acquired by the output resolution acquisition means;
Applied to the image converted by the resolution converting unit based on the resolution of the image received by the image receiving unit, the output resolution acquired by the output resolution acquiring unit, and the processing conditions received by the image receiving unit Processing determining means for determining processing conditions for frequency correction processing to be performed;
An image processing apparatus comprising: a process execution unit that performs a frequency correction process on the image converted by the resolution conversion unit under the processing condition determined by the process determination unit. The process determining unit is configured to perform a frequency correction process on a frequency band of an image corrected by the process performed by the process executing unit according to a processing condition received by the image receiving unit with respect to an image received by the image receiving unit. The image processing apparatus according to claim 1, wherein processing conditions are determined so as to correspond to a frequency band of an image to be corrected. The degree of correction by the processing by the processing execution unit is corrected when the frequency correction processing is performed on the image received by the image receiving unit according to the processing condition received by the image receiving unit. The image processing apparatus according to claim 1, wherein the processing condition is determined so as to correspond to the degree. An image receiving step for receiving an image to which processing conditions and resolution of frequency correction processing to be applied to the image are added;
An output resolution acquisition step for acquiring an output resolution;
A resolution conversion step of converting the received image resolution into the acquired output resolution;
A process determining step for determining a processing condition of a frequency correction process to be applied to an image whose resolution has been converted based on the resolution of the received image and the acquired output resolution and the received processing condition;
A program that causes a computer to execute a processing execution step of performing frequency correction processing on an image whose resolution is converted under the determined processing conditions.

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