JP2005275901A - Image processing method for correcting unnecessary area of image, program, and image processor for performing the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide image processing technique for suppressing unnaturalness in pixel copying. <P>SOLUTION: An unnecessary area is selected from an inputted image, so as to set a plurality of direction lines which are radially extended from the unnecessary area with successively set notice pixels as a center. A temporary correction value for the notice pixels is calculated with the use of the pixel values of reference pixels which are positioned at both the sides of the notice pixels along the respective direction lines. A weight coefficient for each direction line is calculated with the use of the pixel value of the reference pixel which is set along each direction line. The weighting average value of the temporary correction value of the notice pixel is calculated as the final correction value of the notice pixel through the use of the temporary correction value obtained at each direction line and the weight coefficient. Thus, the unnecessary area is corrected through the use of the final correction value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image processing technique for correcting an unnecessary area by replacing unnecessary pixels constituting an unnecessary area of an image with reference pixels adjacent to the outside of the unnecessary area.

  A photographed image often includes unnecessary areas such as utility poles and electric wires in landscape images, spots and dust in human images, and in some cases wrinkles and moles. A so-called pixel copy processing algorithm that replaces unnecessary pixels constituting these unnecessary areas with peripheral (outside unnecessary areas) pixels (this is called a reference pixel) is implemented as an important tool of photo retouching software. Use the mouse to manually replace the specified pixel unit. However, in the case of manual pixel copying, in the case where there are a plurality of unnecessary areas, or in the case where the unnecessary area is wide-ranging, a pixel that has been replaced once is replaced with another unnecessary pixel as a reference pixel. If this happens frequently, the correction area will be an unnatural image.

In the simplest automatic pixel copy, since the positional relationship between the unnecessary pixel to be corrected and the reference pixel to be corrected is maintained constant, the image pattern around the unnecessary area that becomes the reference pixel is corrected. Since the modified image becomes unnatural after mapping to the pixel area, the pixel data of the predetermined copy source pixel candidate area is sequentially selected and copied as the copy source pixel area, and the subsequent copy destination position changes. By sequentially copying the pixel data of the copy source pixel candidate area in the same adjacent order every time, that is, by fixing the position of the plurality of pixel areas given as the copy source regardless of the change of the copy destination position, There is known an automatic pixel copy technique for preventing an image around a copy source pixel area from being directly transferred to a copy destination image (for example, Patent Documents). Reference.). However, with this technique, even if the image around the copy source pixel area is prevented from being transferred to the copy destination image as it is, not only the corrected image becomes unnatural depending on the selection of the copy source pixel area, but also the correction The image is blurred, and the continuity of the contour with the surrounding area is almost lost.
Japanese Unexamined Patent Publication No. 2000-67211 (paragraph numbers 0003, 0031, 0032, FIG. 4)

  In view of the above situation, the problem of the present invention is that when an unnecessary area is corrected by replacing an unnecessary pixel constituting an unnecessary area of an image with a reference pixel adjacent to the outside of the unnecessary area, the replaced pixel is further classified as a reference pixel. It is to provide an image processing technique that can prevent the continuity of the contour of the correction area from being completely lost with the surrounding area by freely selecting the reference pixel and freely selecting the reference pixel. .

  In order to achieve the above object in an image processing method for correcting an unnecessary area by replacing unnecessary pixels constituting an unnecessary area of an image with a reference pixel adjacent to the outside of the unnecessary area, in the method according to the present invention, an input is provided. Selecting the unnecessary area from the selected image; setting a target pixel sequentially from the selected unnecessary area; setting a plurality of direction lines extending radially from the target pixel; Searching for the reference pixels located on both sides of the target pixel along a direction line, and calculating a temporary correction value for the target pixel using a pixel value of the searched reference pixel; Calculating a weighting factor for each direction line using pixel values of reference pixels set along each direction line; and obtaining for each search line. A step of calculating a weighted average value of the temporary correction value of the target pixel as the final correction value of the target pixel using the temporary correction value and the weighting factor, and the unnecessary area using the final correction value. And the step of correcting.

  In this method, as long as an unnecessary area in the image is selected, the correction value based on the pixel value of the reference pixel existing along the direction line in a plurality of directions is automatically automatically set for each unnecessary pixel after that. A temporary correction value is obtained, and further, a weighting factor for each direction line is obtained based on the pixel values of the reference pixels existing along each direction line, and a weighted average value using the weight coefficient is used to calculate unnecessary pixels. Since the correction is performed, it is possible to obtain a final correction value corresponding to the contour of the image existing in each direction line around the unnecessary pixel, and it is possible to perform an appropriate correction process that accurately reflects the contour of the image. . Therefore, it is suppressed that the continuity of the contour between the correction area and the surrounding area is completely lost.

  In addition, when the unnecessary area is selected a plurality of times, the selected unnecessary areas are integrated and set as one unnecessary area, and the target pixel is sequentially set from the unnecessary area integrated into one, By performing the unnecessary pixel correction process described above, it is possible to prevent a pixel that has been replaced once from being replaced with another unnecessary pixel as a reference pixel.

  In addition, by adjusting the search interval along each direction line when searching for the reference pixel according to the size (number of pixels) of the unnecessary region to be corrected, the direction in which the contour exists according to the size of the unnecessary region It is possible to reduce the amount of calculation processing for the search, and the processing speed can be increased.

  As a preferred embodiment of the present invention, the weighting factor is a value using a pixel value of a reference pixel searched on one side across the target pixel along each direction line and a reference pixel searched on the other side. It is proposed to use the larger value of the pixel value of the pixel value as the denominator and the smaller value as the numerator. According to this, since the weight coefficient can be increased as the pixel value of one or more reference pixels located on both sides of the target pixel along the direction line is closer, the direction in the appropriate interpolation direction The pixel of interest (unnecessary pixel) can be corrected by increasing the weighting coefficient for the line.

  As a preferred embodiment of the present invention, the temporary correction value is a value using a pixel value of a reference pixel searched on one side across the target pixel along the direction line and a reference searched on the other side. It is proposed to be obtained by linear interpolation between values using pixel values of pixels. According to this, attention is paid based on the pixel values of one or more reference pixels located on both sides of the target pixel along each direction line and the distance between the reference pixels located on both sides thereof. Appropriate provisional correction values for pixels (unnecessary pixels) can be calculated.

  In the present invention, a program for causing a computer to execute the above-described image processing method for correcting an unnecessary area and a medium on which the program is recorded are also subject to rights.

In the present invention, an image processing apparatus that performs the above-described image processing method for correcting an unnecessary area is also subject to the right, and such an image processing apparatus does not need to select an unnecessary area from an input image. A region selection unit; a target pixel setting unit that sequentially sets a target pixel from the selected unnecessary region; a calculation direction line setting unit that sets a plurality of direction lines extending radially from the target pixel; A reference pixel search unit that searches for the reference pixels located on both sides of the target pixel along the line, and calculates a temporary correction value for the target pixel using the pixel value of the searched reference pixel Temporary correction value calculation unit, weighting factor calculation unit for calculating a weighting factor for each direction line using pixel values of reference pixels set along each direction line, and each search line Temporary repair A final correction value calculation unit that calculates a weighted average value of the provisional correction values of the target pixel as a final correction value of the target pixel using the value and the weighting factor; and the unnecessary area using the final correction value. And an unnecessary area correction unit to be corrected. Naturally, such an image processing apparatus also includes all the embodiments described in the above-described image processing method, and can obtain the effects thereof.
Other features and advantages of the present invention will become apparent from the following description of embodiments using the drawings.

  A photographic printing apparatus equipped with an image processing unit employing an image processing function for correcting an unnecessary area according to the present invention will be described. FIG. 1 is an external view showing the photographic printing apparatus. This photographic printing apparatus includes a printing station 1B as a photographic printer that performs exposure processing and development processing on photographic paper P, a developed photographic film 2a, and a digital camera. It comprises an operation station 1A that processes a captured image taken from an image input medium such as a camera memory card 2b and generates / transfers print data used in the print station 1B.

    This photo printing apparatus is also called a digital minilab. As can be understood from FIG. 2, the printing station 1B pulls out the roll-shaped printing paper P stored in the two printing paper magazines 11 and prints it with the sheet cutter 12. The back print unit 13 prints print processing information such as color correction information and frame number on the back side of the photographic paper P, and the print exposure unit 14 cuts the print paper P into the size. A photographed image is exposed on the surface of the photographic paper P, and the exposed photographic paper P is sent to a processing tank unit 15 having a plurality of development processing tanks for development processing. After drying, the photographic paper P, that is, the photographic prints P, sent to the sorter 17 from the transverse feed conveyor 16 at the upper part of the apparatus is collected in a plurality of trays of the sorter 17 in a state of being sorted in order units (see FIG. 1). ).

  A photographic paper transport mechanism 18 is laid to transport the photographic paper P at a transport speed in accordance with various processes for the photographic paper P described above. The photographic paper transport mechanism 18 is composed of a plurality of nipping and transporting roller pairs including a chucker type photographic paper transport unit 18a disposed before and after the print exposure unit 14 in the photographic paper transport direction.

  The print exposure unit 14 applies R (red), G (green), and B (blue) to the printing paper P conveyed in the sub-scanning direction based on print data from the operation station 1A along the main scanning direction. A line exposure head for irradiating laser beams of the three primary colors (1) is provided. The processing tank unit 15 includes a color developing tank 15a for storing a color developing processing liquid, a bleach-fixing tank 15b for storing a bleach-fixing processing liquid, and a stabilizing tank 15c for storing a stable processing liquid.

  At the upper position of the desk-like console of the operation station 1A, there is a film scanner 20 capable of acquiring photographed image data (hereinafter simply referred to as image data) from a photographed image frame of the photographic film 2a with a resolution exceeding 2000 dpi. A media reader 21 that is arranged and obtains image data from various semiconductor memories, CD-Rs, etc., used as a photographic image recording medium 2b mounted on a digital camera or the like functions as the controller 3 of this photographic printing apparatus. Built into a general-purpose personal computer. The general-purpose personal computer is also connected with a monitor 23 for displaying various information, and a keyboard 24 and a mouse 25 as operation input devices used as an operation input unit used for various settings and adjustments.

  The controller 3 of this photographic printing apparatus uses a CPU as a core member and constructs a functional unit for performing various operations of the photographic printing apparatus by hardware and / or software, as shown in FIG. As described above, the functional unit particularly related to the present invention includes an image input unit 31 that takes in image data read by the film scanner 20 and the media reader 21 and performs preprocessing necessary for the next processing, Graphic user interface (hereinafter abbreviated as GUI) that generates a control command from creation of a graphic operation screen including a window, various operation buttons, and the like, and user operation input through such a graphic operation screen (using the keyboard 24, mouse 25, etc.) Sent from the GUI unit 33 and the GUI unit 33 A print management unit 32 that performs image processing on the image data transferred from the image input unit 31 to the memory 30 in order to generate desired print data based on a control command or an operation command directly input from the keyboard 24 or the like. Video control for generating a video signal for causing the monitor 23 to display graphic data sent from the GUI source 33, a simulated image as a print source image, an expected finished print image, and a pre-judge print operation such as color correction A print data generation unit 36 for generating print data suitable for the print exposure unit 14 installed in the print station 1B based on the processed image data for which image processing has been completed, Image data or processed image data that has been processed Etc. etc. formatter 37 that formats the format for writing to CD-R can be mentioned a.

  When the photographic image recording medium is the film 2a, the image input unit 31 separately sends the scan data for the pre-scan mode and the main scan mode to the memory 30, and performs preprocessing according to each purpose. Further, when the captured image recording medium is the memory card 2b, when the captured image data includes thumbnail image data (low resolution data), the actual data of the captured image is used for the purpose of displaying a list on the monitor 23. Separately from (high resolution data), it is sent to the memory 30, but if thumbnail image data is not included, a reduced image is created from this data and sent to the memory 30 as thumbnail image data.

  The print management unit 32 includes a print order processing unit 60 that manages the print size, the number of prints, and the like, and an image processing unit 70 that performs various image processes on the image data developed in the memory 30.

  The above-described image processing unit 70 includes unnecessary area correction processing means 80 adopting the technique according to the present invention and means for realizing a photo retouch function such as density correction and resolution conversion. The unnecessary area correction processing means 80 is substantially implemented in the image processing unit 70 as a program. However, as shown in FIG. 4, the input photographed image displayed in the monitor 23 while being expanded in the memory 30. An unnecessary area and a reference area (normal area) are partitioned from the position information of the area selected using the keyboard 24 and the mouse 25, with the utility poles and electric wires in the landscape image while looking at the eyes, and moles and wrinkles in the person image as unnecessary areas. An unnecessary area selection unit 81 that creates a prescribed processing map, a target pixel setting unit 82 that sequentially sets a target pixel from the selected unnecessary area, and a plurality of direction lines that extend radially around the set target pixel A calculation direction line setting unit 83 for setting the reference pixel and searching for the reference pixels located on both sides of the target pixel along each set direction line A reference pixel search unit 84, a temporary correction value calculation unit 85 that calculates a temporary correction value for the pixel of interest using the pixel value of the searched reference pixel, and a pixel of the reference pixel set along each direction line A weighting coefficient calculation unit 86 for calculating a weighting coefficient for each direction line using the value, and a weighted average value of the temporary correction value of the target pixel using the temporary correction value and the weighting coefficient obtained for each direction line As a final correction value for the target pixel, and an unnecessary area correction unit 88 for correcting the unnecessary area using the final correction values obtained for all unnecessary pixels. . Furthermore, in this embodiment, the search interval adjusting unit 89a that adjusts the search pixel interval when searching for the reference pixel according to the size (number of pixels) of the unnecessary region to be corrected, and the unnecessary region to be corrected There is also provided a search angle adjustment unit 89b that adjusts the angle interval (that is, the number of set direction lines) of each direction line set for the target pixel in accordance with the size (number of pixels).

  An image processing procedure for unnecessary area correction by the unnecessary area correction processing unit 80 configured as described above will be described below. The flow of this image processing is shown in FIG. 5. First, a photographed image, specifically, digital image data of the photographed image is captured through the film scanner 20 and the media reader 21 and developed in the memory 30. In general, the image frames for one film and one memory card are sequentially displayed in a captured image display frame 41 of an operation input screen 40 called a pre-judge screen for image check. In FIG. 6, a six-frame display screen is selected. A color density correction setting area 42 and a print number setting area 43 are arranged below each captured image display frame 41. The color density correction setting area 42 is provided with setting frames of “yellow”, “magenta”, “cyan”, and “density”, and the correction amount “N” represents neutral and means no correction. The print number setting area 43 is provided with a print number input frame, and “pass” means that printing is not performed. A print condition display field 44 is arranged below the pre-judge screen 40. The print channel name applied to the photo print output, the print size included in the print channel, the necessity of index print, The necessity of media output is shown. The print size indicates the size of the finished photo print P. In this embodiment, the print size is determined by the photographic paper width and the feed length. When various correction settings and print number settings for each photographed frame image are completed on the pre-judge screen 40, the corresponding photographed image data is sent to the print data generation unit 36 and converted into print data.

  A correction main screen 50 as shown in FIG. 7 is displayed by selecting and double-clicking a frame that requires unnecessary area correction from among many frames displayed on the monitor 23. An enlarged image display area 51 is arranged in the center of the corrected main screen 50, and a display confirmation area 52 that shows a portion of the captured frame image that is displayed in the enlarged image display area 51 with a frame line at the right end. Various correction buttons such as an unnecessary area correction button 53 are arranged. The portion displayed in the enlarged image display area 51 can be changed by moving the frame line of the display confirmation area 52 using the mouse 25, and the enlarged image display area can be changed by changing the enlargement ratio of the display size area 52a. The image displayed on 51 can be enlarged or reduced. An unnecessary area is selected on the correction main screen 50 using the mouse 25. In that case, it is also possible to select a plurality of areas. Note that this area selection can be performed by a completely manual method in which the operator drags the outlines of all the density-impaired areas with a mouse or the like, or when the operator only points to one point in the density-impaired area by a predetermined algorithm. Either a semi-automatic method for selecting an area or a fully automatic method for automatically performing all of the areas may be used (# 01).

  When the selection of the unnecessary area on the monitor screen is completed, all the selected unnecessary areas are integrated to form a single unnecessary area. A processing map as shown in FIG. 8 is created from this unnecessary area on the screen and other reference areas (# 02). Further, the search interval adjustment unit 89a determines a search interval along the direction line L when searching for the reference pixel P according to the number of pixels included in the unnecessary region (# 03), and the search angle adjustment unit 89b Then, according to the number of pixels included in the unnecessary area, the angular interval between the adjacent direction lines L when searching for the reference pixel is determined (# 04). In other words, according to the number of pixels included in the unnecessary area to be processed, it is preferable to determine that the search interval is increased as the number of pixels is increased and the search interval is decreased as the number of pixels is decreased. For example, when the number of pixels is small, the search interval is set to “0”, the reference pixel P is searched for all the pixels along the direction line L, and when the number of pixels is intermediate, the search interval is set to “1”. The reference pixel P is searched for every other pixel along the direction line L, the search interval is set to “2” for those having a large number of pixels, and the reference pixel P is searched every two pixels along the direction line L. be able to. It is also possible to express the number of pixels of the unnecessary area to be processed and the search interval by a fixed relational expression, and calculate and determine the search interval each time correction processing is performed. In addition, the angular interval between adjacent direction lines L when searching for a reference pixel is also reduced as the number of pixels increases according to the number of pixels included in the unnecessary area to be processed. It is preferable that the smaller the number, the larger the angular interval. For example, as in the case of the search interval described above, an angle interval between adjacent direction lines L is set to “10 °” when the number of pixels is large, and an angle interval between adjacent direction lines L when the number of pixels is intermediate. Can be set to “20 °” and the angle interval between adjacent direction lines L can be set to “30 °” when the number of pixels is small. Also, without using such a table, the number of pixels in the unnecessary area to be processed and the angle interval between the direction lines L can be expressed by a fixed relational expression, and the angle interval can be calculated and determined each time correction processing is performed. Is possible.

  Next, in the pixel-of-interest setting unit 82, one pixel of interest O (a pixel indicated by a diagonal line having a large central interval width in FIG. 9) is set from the pixels regarded as unnecessary pixels in the unnecessary region selection unit 81. (# 05). The target pixel O is set from pixels that are registered as unnecessary pixels in the processing map and have not yet been selected as the target pixel O. At this time, it is possible to set an arbitrary pixel from unnecessary pixels that have not yet been selected as the target pixel O, but eventually all unnecessary pixels included in the unnecessary area are set as the target pixel O. To be.

Next, the calculation direction line setting unit 83 sets direction lines L in a plurality of directions passing through the target pixel O (# 06).
Thereafter, the reference pixel search unit 84 searches for the reference pixels P on both sides of the target pixel O along the set direction line L (# 07). FIG. 9 shows an example when searching for the reference pixel P along a plurality of direction lines L passing through the target pixel O. In this figure, the search interval determined in the process of # 03 is “2”, and the angle interval between the direction lines L determined in the process of # 04 is “15 °”. Here, the direction line L is a line in which two opposite directions existing on a straight line across the target pixel O among a plurality of radial directions centered on the target pixel are one.

  When searching for the reference pixel P along the direction line L, if the angular interval between adjacent direction lines L is other than 90 ° or 45 °, the direction line L may not pass through the center of all the pixels. In this case, the pixel having the closest center position to the position through which the direction line L passes is regarded as a pixel on the direction line L. When searching for the reference pixel P, the search is performed at the predetermined search interval for pixels on the direction line L including the pixels regarded as such. In FIG. 9, since the search interval is “2”, it is determined whether the pixel is an unnecessary pixel or a reference pixel every other pixel from the target pixel O along the direction line L outward. Are searched for as reference pixels P located on both sides of the target pixel O along the direction line L. In the present embodiment, one reference pixel P is searched for on both sides of the target pixel O along the direction line L, and the value of the reference pixel P is used to determine the subsequent target pixel O. The provisional correction value H and the weighting factor W are calculated as interpolation values. However, two or more reference pixels P are searched for on both sides of the target pixel O, and the two or more reference pixels P are searched. It is also possible to employ a configuration in which the temporary correction value H and the weighting factor W of the target pixel O later are calculated using the average value of The search for the reference pixel P is not limited to the direction line L as described above, and the reference pixel P including the reference pixel P located in the vicinity of the direction line L may be searched.

  Then, as a result of searching for the reference pixel P along the one direction line L, it is determined whether or not the reference pixel P exists within a predetermined distance on both sides of the target pixel O (# 08). This is because the value of the reference pixel P at a position far from the target pixel O is not suitable for use in correcting the target pixel O. Therefore, when there is no reference pixel within a predetermined distance set in advance, This is because the value of the reference pixel P for the direction line L in that direction is not used for the calculation of the temporary correction value H and the weighting factor W of the target pixel O. Accordingly, when there is no reference pixel within a predetermined distance on either one of the both sides across the target pixel O (# 08: NO), the process returns to # 06, and the next one direction line A process of searching for the reference pixel P along L is performed. Here, for example, the predetermined distance may be a constant value represented simply by a distance (number of pixels) such as “25” pixels, or may be processed as “25 × (search interval)” pixels. The value may be changed according to the number of pixels included in the target image data.

On the other hand, if the reference pixel P exists within a predetermined distance on both sides of the target pixel O (# 08: YES), then the temporary correction value calculation unit 85 finds it at # 08. Using the pixel value of the reference pixel P, a temporary correction value H of the target pixel O for the direction line L searched for the reference pixel P is calculated (# 09). As a method of calculating the temporary correction value H of the target pixel O, for example, linear interpolation can be applied. Specifically, reference pixels located on both sides of the target pixel O along one direction line L1 shown in FIG. 9 are denoted as P1 and P2, respectively, and attention is paid using the pixel values of these reference pixels P1 and P2. When calculating the temporary correction value H1 of the pixel O, for each of the R, G, and B components, as shown in FIG. 10, the pixel value of the reference pixel P1 and the pixel value of the reference pixel P2 are linearly represented. Finally, the values on the straight line corresponding to the ratio of the distance from the target pixel O to the reference pixel P1 or P2 are calculated by linear interpolation, and set as temporary correction values H1r, H1g, and H1b of the target pixel O. Here, the vertical axis of the graph of FIG. 10 represents the pixel value of each pixel, and the horizontal axis represents the positional relationship of each pixel located along the direction line L1. An arithmetic expression of the provisional correction value H of the target pixel O according to the present embodiment is specifically shown by the following expression (1) by taking R of the R, G, and B components as an example.

  Here, Rdat1 is a value obtained by logarithmically converting the R component pixel value of one reference pixel P1 located across the target pixel O, Rdat2 is a value obtained by logarithmically converting the R component pixel value of the other reference pixel P2, and rad1 Is the absolute value of the distance from the target pixel O to the reference pixel P1, rad2 is the absolute value of the distance from the target pixel O to the reference pixel P2, (m, n) is the coordinates of the target pixel O, and agl passes through the target pixel O. A value for each angle interval between the direction lines L, which is an angle of the plurality of direction lines L and determined in the process of # 05, is taken. Hragl, m, n is a provisional correction value of the R component of the target pixel O with respect to the direction line L. Although the base of the logarithm when logarithmically converting the pixel values of the R components of the reference pixels P1 and P2 is “e” here, a natural logarithm is used, but a common logarithm may be used. Note that here, values obtained by logarithmically converting the pixel values of the reference pixels P1 and P2 are used, but it is also possible to perform subsequent calculations using these pixel values as they are.

  For the G component and the B component, the temporary correction values H1g and H1b can be calculated by the same method. Note that the method of calculating the temporary correction value H of the pixel of interest O is not limited to linear interpolation, and other interpolation methods can be used.

  Next, the weighting factor calculation unit 86 calculates the weighting factor W for the direction line L searched for the reference pixel P using the pixel value of the reference pixel P searched for in # 07 (# 10). The weighting factor W1 for one direction line L1 is calculated for the direction line L in the other direction as will be described later with the temporary correction value H1 of the target pixel O calculated for one direction line L1 in the process of # 09. In relation to the temporary correction value H of the target pixel O, what ratio (weight) is used for the final correction value (weighted average value A), that is, the temporary correction of the target pixel O for each direction line L This is a coefficient that determines the reliability of how much the correction value H is an appropriate value.

  In general, when the pixel value of the reference pixel P1 and the pixel value of the reference pixel P2 located on both sides of the target pixel O along one certain direction line L are separated from each other, the reference pixel P1 There is a high possibility that there is a boundary between the images, that is, a color transition in the image, and the pixel value of the reference pixel P2 is close to the pixel value of the reference pixel P2. There is a high possibility that no image boundary exists between the reference pixel P1 and the reference pixel P2. In such a case, the temporary correction value H of the unnecessary pixel interpolated in the direction along the image boundary may be more appropriate than the temporary correction value H of the unnecessary pixel interpolated in the direction across the image boundary. It is considered that the nature is high. This is because it is difficult to properly estimate the pixel value of the target pixel O (unnecessary pixel) existing between the reference pixels along the direction in which the change in the pixel value is large, by linear interpolation or the like. This is because an appropriate temporary correction value of the target pixel O can be easily estimated by interpolation along a direction in which a change in value is small.

Therefore, in the present embodiment, the ratio of the R, G, and B components using the larger value of the pixel value of the reference pixel P1 and the pixel value of the reference pixel P2 as the denominator and the smaller value as the numerator. Are calculated as weighting factors Wr, Wg, and Wb. As a result, the weighting coefficient W is calculated as a coefficient that increases the weight as the pixel value of the reference pixel P1 and the pixel value of the reference pixel P2 are closer. An equation for calculating the weighting factor W according to the present embodiment is specifically shown by the following equation (2) by taking R of R, G, and B components as an example.

  Here, max (Rdat1, Rdat2) is the larger value of Rdat1 or Rdat2, min (Rdat1, Rdat2) is the smaller value of Rdat1 or Rdat2, and Wragl, m, n is the direction line L. Is a weighting factor for. Note that when both values of Rdat1 and Rdat2 are “0”, Wragl, m, n is set to “1” in order to avoid calculation being impossible. For the G component and the B component, the weighting factors Wg and Wb can be calculated by the same method.

The calculation method of the weighting factor W for the direction line L is not limited to the above method, and the absolute value of the difference between the pixel value of the reference pixel P1 and the pixel value of the reference pixel P2 with respect to the predetermined value α. A value obtained by dividing the complement by a predetermined value α may be calculated for each of the R, G, and B components to obtain weighting factors Wr, Wg, and Wb. The equation for calculating the weighting factor W is specifically shown as the following equation (3) by taking R of the R, G, and B components as an example.

  Here, the predetermined value α is preferably set to the maximum value that can be taken by the absolute value of the difference between the pixel value of the reference pixel P1 and the pixel value of the reference pixel P2. Thereby, the weight coefficient W can be increased as the pixel value of the reference pixel P1 and the pixel value of the reference pixel P2 are closer. Note that the value of the predetermined value α is not limited to this, and can be set to a value equal to or less than the maximum value that the absolute value of the difference between the pixel value of the reference pixel P1 and the pixel value of the reference pixel P2 can take. It is. However, in this case, the complement may be a negative value. Therefore, when the complement is “0” or less, a condition such as setting the weighting factor W to “0” is necessary. . Here, the complement is divided by the predetermined value α in order to make the weighting factor W be a value between “0” and “1”, but the complement is divided by the predetermined value α. Alternatively, the weight coefficient W can be used.

  Next, whether or not the processes of # 07 to # 10 have been completed for all the direction lines L in a plurality of directions passing through the target pixel O set according to the angular interval between the direction lines L determined in the process of # 04. (# 11). If the processes of # 06 to # 09 for all of the direction lines L in the plurality of directions are not completed (# 11: NO), the process returns to # 06, and the process has already been completed. A direction line L other than the line L is selected, and the processes of # 07 to # 10 are performed again.

On the other hand, when the processing of # 07 to # 10 is completed for all of the direction lines L in the plurality of directions (# 11: YES), the final correction value calculation unit 87 selects the 1 selected in the processing of # 05. A weighted average value A for the target pixel O is calculated (# 12). That is, using the temporary correction value H and the weighting factor W of the target pixel O for each direction line L calculated in the processes of # 05 to # 10, the temporary correction value H of the selected one target pixel O is weighted. An average value A (final correction value) is calculated. Specifically, for each of the R, G, and B components, a multiplication value obtained by multiplying the provisional correction value H for each direction line L by the nth power of the weighting factor W for the direction line L is used as the target pixel. This is performed by summing all of the plurality of direction lines L passing through O, and dividing this sum by the sum of the nth powers of all the weighting factors W used for the calculation of the multiplication value. The calculation formula of the weighted average value A is specifically shown by the following formula (4) by taking R of the R, G, and B components as an example.

  In the present embodiment, 12 direction lines L passing through the target pixel O are set at 15 ° intervals, and for each of the R, G, and B components, temporary correction values Hr, Hg, and Hb are set. Since the weighting factors Wr, Wg, and Wb are calculated, the weighted average value A is the sum of the twelve provisional correction values H and the multiplication value of the weighting factor W raised to the nth power, and the twelve weighting factors W It is calculated by dividing by the sum of the nth power.

  Here, since the weighting coefficient W is a value between “0” and “1”, the value of the weighting coefficient W can be emphasized by raising the weighting coefficient W to the nth power. As a result, the influence of the temporary correction value H of the target pixel O calculated along the direction in which the boundary of the image around the target pixel O exists on the weighted average value A can be increased, and the image boundary can be increased. Thus, it is possible to correct an unnecessary pixel that reflects the direction of. Here, the value of n is appropriately determined depending on the state of the image to be corrected. Therefore, it is preferable that the value is experimentally obtained from statistics of various images. If the value of n is too small, the corrected image has a blurred image boundary. If the value of n is too large, the corrected image has a too sharp image boundary. . Specifically, in the case of a normal photograph, the value of n is often about 10 to 30, and moreover, as the value of n such that the boundary between skin color and black is appropriately corrected About 20 is often suitable.

Next, the unnecessary area correction unit 88 corrects the target pixel O using the weighted average value A of the target pixel O calculated by the process of # 12 (# 13). Specifically, the weighted average values Ar, Ag, and Ab of the target pixel O calculated for each of the R, G, and B components are subjected to inverse logarithm conversion, and the values are converted into final correction values of the target pixel O. Fr, Fg, and Fb are used, and these are replaced with the pixel values of the R, G, and B components of the target pixel O. When the arithmetic expression of the final correction value F is specifically shown by taking R of the R, G, and B components as an example, the following expression (5) is obtained.

  As described above, when the final correction value F is calculated, the weighted average value A of the target pixel O is subjected to inverse logarithm conversion when the temporary correction value H of the target pixel O is calculated in the process of # 08. This is because the R component pixel values of the pixels P1 and P2 are logarithmically converted. Therefore, here, the inverse logarithmic transformation is performed by the base “e” of the natural logarithm. In the above equation (1), when the pixel values of the reference pixels P1 and P2 are used without being subjected to logarithmic conversion, the inverse logarithmic conversion process is not performed, and thus the weighted average value of the pixel of interest O Ar, Ag, and Ab are the final correction values as they are.

  Next, it is determined whether all unnecessary pixels registered as unnecessary pixels in the processing map in the process of # 02 are selected as the target pixel O and the processes of # 05 to # 13 have already been completed (# 14). If all unnecessary pixels have not been selected as the target pixel O (# 14: NO), the process returns to # 05, and a target pixel O other than the target pixel O that has already been processed is selected. , # 05 to # 13 are repeated. When all unnecessary pixels are selected as the target pixel O and the processes of # 05 to # 13 have already been completed (# 14: YES), the unnecessary area correction process is ended.

1 is an external view of a photographic printing apparatus equipped with an image processing unit that employs an unnecessary area correction image processing technique according to the present invention. Schematic diagram schematically showing the configuration of the print station of the photo printing device Functional block diagram explaining the functional elements built in the controller of the photo printing device Functional block diagram showing the functional configuration of the unnecessary area correction processing means Flowchart showing image processing procedure for correcting unnecessary area Screen image of pre-judge screen Screen view of the main correction screen Illustration of processing map Explanatory drawing which shows an example of the process which searches a reference pixel along the search line of the multiple directions which pass through one target pixel in the correction process of an unnecessary pixel. The graph which shows an example of the calculation method of the temporary correction value of the object pixel in the correction process of an unnecessary pixel

Explanation of symbols

80 Unnecessary region correction processing means 81 Unnecessary region selection unit 82 Target pixel selection unit 83 Calculation direction line setting unit 84 Reference pixel search unit 85 Temporary correction value calculation unit 86 Weight coefficient calculation unit 87 Final correction value calculation unit (weighted average value calculation) Part)
88 Unnecessary region correction unit 89a Search interval adjustment unit 89b Search angle adjustment unit O Target pixel P Reference pixel L Direction line H Target pixel temporary correction value W Weight coefficient A Weighted average value (final correction value)
F Last modified value

Claims (7)

In the image processing method for correcting the unnecessary area by replacing unnecessary pixels constituting the unnecessary area of the image with a reference pixel adjacent outside the unnecessary area,
Selecting the unnecessary area from the input image;
Sequentially setting a target pixel from the selected unnecessary area;
Setting a plurality of direction lines extending radially around the pixel of interest;
Searching for the reference pixels located on both sides of the target pixel along each direction line;
Calculating a temporary correction value for the pixel of interest using a pixel value of the searched reference pixel;
Calculating a weighting factor for each direction line using pixel values of reference pixels set along each direction line;
Calculating a weighted average value of the temporary correction value of the target pixel as the final correction value of the target pixel using the temporary correction value and the weighting coefficient obtained for each search line;
Correcting the unnecessary area using the final correction value;
An image processing method comprising:   2. The image processing method according to claim 1, wherein when the unnecessary area is selected a plurality of times, the selected unnecessary areas are integrated and set as one unnecessary area.   The image processing method according to claim 1, wherein a search interval in the step of searching for the reference pixel is adjusted according to a size of the unnecessary area to be corrected.   The weighting factor is a value using a pixel value of a reference pixel searched on one side across the target pixel along each direction line and a value using a pixel value of a reference pixel searched on the other side. The image processing apparatus according to claim 1, wherein the ratio is a ratio in which a larger value is used as a denominator and a smaller value is used as a numerator.   The temporary correction value is a value using a pixel value of a reference pixel searched on one side across the target pixel along the direction line, and a value using a pixel value of a reference pixel searched on the other side. The image processing apparatus according to claim 1, wherein the image processing apparatus is obtained by linear interpolation. In order to correct the unnecessary area by replacing unnecessary pixels constituting the unnecessary area of the image with reference pixels adjacent outside the unnecessary area,
A function for sequentially setting a pixel of interest from an unnecessary area selected from an input image;
A function of setting a plurality of direction lines extending radially around the target pixel;
A function of searching for the reference pixels located on both sides of the target pixel along each direction line;
A function of calculating a temporary correction value for the target pixel using a pixel value of the searched reference pixel;
A function of calculating a weighting factor for each direction line using a pixel value of a reference pixel set along each direction line;
A function of calculating a weighted average value of the temporary correction value of the target pixel as the final correction value of the target pixel using the temporary correction value and the weighting coefficient obtained for each search line;
A function of correcting the unnecessary area using the final correction value;
An image processing program for realizing a computer. In the image processing apparatus for correcting the unnecessary area by replacing unnecessary pixels constituting the unnecessary area of the image with reference pixels adjacent to the outside of the unnecessary area,
An unnecessary area selection unit for selecting the unnecessary area from the input image;
A pixel-of-interest setting unit that sequentially sets pixels of interest from the selected unnecessary area;
A calculation direction line setting unit that sets a plurality of direction lines extending radially from the target pixel;
A reference pixel search unit that searches for the reference pixels located on both sides of the target pixel along the direction lines;
A temporary correction value calculation unit that calculates a temporary correction value for the target pixel using a pixel value of the searched reference pixel;
A weighting factor calculation unit that calculates a weighting factor for each direction line using a pixel value of a reference pixel set along each direction line;
A final correction value calculation unit that calculates a weighted average value of the temporary correction value of the target pixel as the final correction value of the target pixel using the temporary correction value and the weighting coefficient obtained for each search line;
An unnecessary area correction unit that corrects the unnecessary area using the final correction value;
An image processing apparatus comprising:

Images