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JP-7855971-B2 - Image processing device, printing system, and image processing method

JP7855971B2JP 7855971 B2JP7855971 B2JP 7855971B2JP-7855971-B2

Inventors

  • 奥村 嘉夫
  • 萱原 直樹
  • 中塚 翼
  • 天狗石 悠斗

Assignees

  • セイコーエプソン株式会社

Dates

Publication Date
20260511
Application Date
20220829

Claims (10)

  1. An image processing apparatus capable of performing image processing to obtain a converted image whose resolution has been converted based on an input image having a plurality of pixels arranged in a first direction and a second direction intersecting the first direction, A blurring processing unit capable of generating a blurred image by applying a two-dimensional Gaussian filter, which has a first filter size in the first direction and a second filter size in the second direction, to the input image, The system comprises a resolution conversion unit capable of generating a converted image from the blurred image, wherein the resolution has been converted by a first conversion ratio, which is the resolution conversion ratio in the first direction, and a second conversion ratio, which is the resolution conversion ratio in the second direction. If the blurring processing unit makes the first filter size larger than the second filter size, the second conversion magnification is larger than the first conversion magnification. If the blurring processing unit makes the second filter size larger than the first filter size, the first conversion magnification is larger than the second conversion magnification. Let the standard deviation σ of the Gaussian filter in the first direction be denoted as standard deviation σ1. Let the standard deviation σ of the Gaussian filter in the second direction be taken as the standard deviation σ2. The blurring processing unit applies the Gaussian filter to the input image, wherein the second filter size is different from the first filter size, and the filter coefficients have such that the standard deviation σ2 matches the standard deviation σ1.
  2. The blurring processing unit generates the blurred image when at least one of the first conversion magnification and the second conversion magnification is less than 1. The image processing apparatus according to claim 1, wherein the resolution conversion unit generates a converted image from the input image in which the resolution has been converted by the first conversion ratio in the first direction and the second conversion ratio in the second direction, when the first conversion ratio and the second conversion ratio are 1 or more.
  3. The image processing apparatus according to claim 1, wherein the blurring processing unit sets the first filter size of the Gaussian filter to an odd number greater than the reciprocal of the first conversion ratio when the first conversion ratio is less than 1, and sets the second filter size of the Gaussian filter to an odd number greater than the reciprocal of the second conversion ratio when the second conversion ratio is less than 1.
  4. An image processing apparatus according to any one of claims 1 to 3, A print head having multiple nozzles capable of dispensing liquid onto a medium, A printing system comprising: a control unit that controls the discharge of the liquid from the print head so that a printed image based on the converted image is formed on the medium.
  5. In printing conditions where the resolution of the converted image can be set to one of several different output resolutions, the system further includes a resolution receiving unit that accepts the setting of the resolution of the converted image from among the multiple output resolutions. The output resolution includes a first output resolution and a second output resolution different from the first output resolution. The printing system according to claim 4, wherein the blurring processing unit matches the standard deviations σ1 and σ2 of the Gaussian filter applied to the input image when the second output resolution is received by the resolution receiving unit to the standard deviations σ1 and σ2 of the Gaussian filter applied to the input image when the first output resolution is received by the resolution receiving unit.
  6. The system further includes a print condition receiving unit that accepts the setting of the aforementioned print conditions from among multiple candidates. The printing system according to claim 5, wherein the blurring processing unit can apply the Gaussian filter to the input image using the standard deviations linked to the printing conditions from among the standard deviations σi linked to each of the plurality of candidates as the standard deviations σ1 and σ2.
  7. The aforementioned medium comprises a first medium and a second medium through which the liquid is less likely to seep than through the first medium. The plurality of candidates that can be the printing conditions include a first medium candidate for forming the print image on the first medium, and a second medium candidate for forming the print image on the second medium. The printing system according to claim 6, wherein the blurring processing unit makes the standard deviations σ1 and σ2 of the Gaussian filter applied to the input image when the second media candidate is accepted as a printing condition greater than the standard deviations σ1 and σ2 of the Gaussian filter applied to the input image when the first media candidate is accepted as a printing condition.
  8. The plurality of candidates that can be the printing conditions include a first image candidate that prioritizes the sharpness of the line drawings included in the input image, and a second image candidate that prioritizes the gradation of the input image. The printing system according to claim 6, wherein the blurring processing unit makes the standard deviations σ1 and σ2 of the Gaussian filter applied to the input image when the second image candidate is accepted as a printing condition greater than the standard deviations σ1 and σ2 of the Gaussian filter applied to the input image when the first image candidate is accepted as a printing condition.
  9. The printing system according to claim 4, wherein the blurring processing unit receives an operation on the user interface screen to set the standard deviation σ of the Gaussian filter to be applied to the input image, and applies the Gaussian filter having the filter coefficients with the received standard deviation σ as the standard deviations σ1 and σ2 to the input image.
  10. An image processing method for obtaining a converted image whose resolution has been converted based on an input image having a plurality of pixels arranged in a first direction and a second direction intersecting the first direction, A blurring process that generates a blurred image by applying a two-dimensional Gaussian filter, which has a first filter size in the first direction and a second filter size in the second direction, to the input image; The process includes a resolution conversion step of generating a converted image from the blurred image, in which the resolution has been converted by a first conversion ratio, which is the resolution conversion ratio in the first direction, and a second conversion ratio, which is the resolution conversion ratio in the second direction. In the blurring process described above, if the first filter size is made larger than the second filter size, the second conversion magnification is made larger than the first conversion magnification. In the blurring process described above, if the second filter size is made larger than the first filter size, the first conversion magnification is made larger than the second conversion magnification. Let the standard deviation σ of the Gaussian filter in the first direction be denoted as standard deviation σ1. Let the standard deviation σ of the Gaussian filter in the second direction be taken as the standard deviation σ2. An image processing method comprising: in the blurring step, applying the Gaussian filter to the input image, wherein, when the second filter size is different from the first filter size, the Gaussian filter has filter coefficients such that the standard deviation σ2 matches the standard deviation σ1.

Description

This invention relates to a technique for converting the resolution of an image. To transform the resolution of an image containing multiple pixels arranged in two mutually orthogonal directions, interpolation calculations such as the bicubic interpolation method are used to change the number of pixels in the image. Transforming an image to increase its resolution increases the number of pixels, while transforming it to decrease its resolution decreases it. Here, the two mutually orthogonal directions are the X and Y directions. In particular, when the image resolution is reduced, some pixels within the image will not be used in the resolution transformation, or will have small weights during the interpolation calculation. Therefore, a blurring process, such as applying a Gaussian filter to the image before the resolution transformation, is performed. The print inspection apparatus disclosed in Patent Document 1 applies a Gaussian filter to the RIP (Raster Image Processor) image before resolution conversion for smoothing. The Gaussian filter used has the same size in both the X and Y directions, such as 3x3. The smoothing coefficient σ, or standard deviation, of the Gaussian filter increases as the line screen resolution of the printed material decreases. Japanese Patent Publication No. 2015-53561 A schematic block diagram showing an example configuration of a printing system including an image processing device.This diagram schematically illustrates an example of generating a transformed image where a horizontal Gaussian filter is used for blurring, and then the vertical transformation ratio is greater than the horizontal transformation ratio.This diagram schematically illustrates an example of generating a transformed image where a vertical Gaussian filter is used for blurring, and then the horizontal transformation ratio is greater than the vertical transformation ratio.A schematic diagram illustrating an example of the relationship between the resolution conversion ratio and the filter size of a Gaussian filter.This diagram schematically shows examples of images when a blurring process using a horizontal Gaussian filter is performed, and then a transformed image is generated in which the vertical transformation ratio is greater than the horizontal transformation ratio.A schematic diagram showing an example of diagonal lines after resolution conversion.This diagram schematically shows an example of a converted image obtained from an input image containing vertical thin lines by changing the resolution in the Y direction.A schematic diagram showing examples of standard deviations σi associated with each printing condition.A flowchart schematically illustrating an example of print control processing.A schematic diagram illustrating an example of a user interface screen.A flowchart schematically illustrating an example of the blurring image generation process.A schematic diagram showing an example of filter coefficients for a Gaussian filter.This diagram schematically shows comparative examples of converted images obtained from input images containing vertical thin lines by changing the resolution in the Y direction. The following describes embodiments of the present invention. Of course, the following embodiments are merely illustrative of the present invention, and not all of the features shown in the embodiments are necessarily essential to the solution of the invention. (1) Overview of the technology included in the present invention: First, an overview of the technology included in the present invention will be described with reference to the examples shown in Figures 1 to 13. Note that the figures in this application are schematic examples, and the magnification in each direction shown in these figures may differ, and the figures may not be consistent. Of course, the elements of this technology are not limited to the specific examples indicated by the reference numerals. In the "Overview of the Technology Included in the Present Invention," the text in parentheses indicates supplementary explanation of the preceding word. [Aspect 1] An image processing apparatus U0 according to one aspect of this technology is an image processing apparatus U0 capable of performing image processing to acquire a converted image IM2 whose resolution has been converted based on an input image IM1 having a plurality of pixels PX1 arranged in a first direction D1 and a second direction D2 intersecting the first direction D1, as illustrated in Figures 2 and 3. The image processing apparatus U0 comprises a blurring processing unit U1 and a resolution conversion unit U2. The blurring processing unit U1 can generate a blurred image IM11 by applying a two-dimensional Gaussian filter F0 having a first filter size S1 in the first direction D1 and a second filter size S2 in the second direction D2 to the input image IM1. The resolution conversion unit U2 can generate the converted image IM2 from the blurred image IM11, in which the