JP3763880B2 - Color correction method - Google Patents

Description

[0001]
[Industrial application fields]
  In the medical or beauty field, the present invention is used for recording color images of human skin and the like.CanColor chart for image recordingTheThe present invention relates to the color correction method used.
[0002]
[Prior art]
In the medical and beauty fields, color images of human skin are often recorded in photographs and videos.
[0003]
For example, in order to determine skin lesions in dermatology, color of wrinkles in orthopedic surgery, determination of therapeutic effect, and determination of cosmetic effect in beauty, a face is often photographed or video-shooted.
[0004]
[Problems to be solved by the invention]
Here, photography and video are taken multiple times with the passage of time for the same patient, etc., but the amount of natural light, the type of illumination light source including natural light, and photography each time it is taken If the color of the room, the film manufacturer, the developing company, and the like are different, there is a problem in that the photographed image may be a different color even for the same person.
[0005]
In comparison with other clinical cases, naturally, the skin color of the patient or the like is often different, which makes comparison more difficult.
[0006]
Furthermore, with respect to the size of the image, since it is difficult to make the distance, magnification, and the like exactly the same for each shooting, changes are unavoidable, making accurate comparison and determination difficult. was there.
[0007]
On the other hand, it is conceivable to correct the color and size of the obtained image by computer processing. However, since the reference is unclear, correction is easily performed arbitrarily. There is a problem of lack of accuracy in general comparison.
[0008]
  The present invention has been made in view of the above-described conventional problems, and corrects a recorded image to a color close to a subject and compares a plurality of individually shot images under the same conditions.In the pictureColor chart for image recordingUse the method to correct the color of the recorded imageThe purpose is to provide.
[0011]
[Means for Solving the Invention]
  ThisThe invention comprises a sheet-like base material such as paper, resin film, etc., and has an adhesive layer that can be attached to a subject on the back side, the base material surface is mat-like, and the base material surface has at least A process of sticking an image recording color chart in which three color materials are applied to different sections in a mat shape to the subject by the adhesive layer and photographing the subject together with the subject, and storing the photographed image as digital data A process of displaying digital data captured in the storage device on a display, and a process of reading color values of the color chart for image recording on the display of at least two of the three colors. The correction value for each color is obtained from the digital data of the color value of the read color chart and the target value in the corresponding section in the color chart for image recording. And a step of correcting the digital data captured in the storage device by the calculated correction value and importing it again into the storage device, and the target values of the color values of the three colors are set in advance. A color correction method that sets and reads the color value of each section in the image on the display and calculates a correction value from the digital data of the read color value and the target value, wherein the color material is white, Black, gray and white and black target values O_H, O_LIs set in advance and the RGB value I of the white section of the image displayed on the display is set._H(R), I_H(G), I_H(B) is read and (0,0)-(I) in a two-dimensional graph having the read value and the corresponding target value as coordinate axes._H, O_H)-(255,255)Correction curveBased on the captured RGBValue I _H (R) , I _H (G) , I _H (B)And then the RGB value I of the black section_L(R), I_L(G), I_L(B) is read and (0,0)-(I) in a two-dimensional graph having the read value and the corresponding target value as coordinate axes._L, O_L)-(255,255)Correction curveBased on the aboveIs capturedRGBValue I _L (R) , I _L (G) , I _L (B)And then the RGB value I of the gray section_M(R), I_M(G), I_MRead (B), this readingI _M (R) , I _M (G) , I _M (B)Average value Ave (I_M) And (0,0)-(I) in a two-dimensional graph having the read value and the corresponding target value as coordinate axes._M, Ave (I_M))-Pass through each point of (255, 255)Correction curveBased on the aboveIs capturedRGBValue I _M (R) , I _M (G) , I _M (B)The above-mentioned object is achieved by converting.
[0012]
  Claim2The invention comprises a sheet-like base material such as paper, resin film, etc., and has an adhesive layer that can be attached to a subject on the back side, the base material surface is mat-like, and the base material surface has at least A process of sticking an image recording color chart in which three color materials are applied to different sections in a mat shape to the subject by the adhesive layer and photographing the subject together with the subject, and storing the photographed image as digital data A process of displaying digital data captured in the storage device on a display, and a process of reading color values of the color chart for image recording on the display of at least two of the three colors. The correction value for each color is obtained from the digital data of the color value of the read color chart and the target value in the corresponding section in the color chart for image recording. And a step of correcting the digital data captured in the storage device by the calculated correction value and importing it again into the storage device, and the target values of the color values of the three colors are set in advance. A color correction method that sets and reads the color value of each section in the image on the display and calculates a correction value from the digital data of the read color value and the target value, wherein the color material is white, Black, gray, and the target value O of these color values_H, O_L, O_MIs set in advance and the RGB value I of the white section of the image displayed on the display is set._H(R), I_H(G), I_H(B) is read and (0,0)-(I) in a two-dimensional graph having the read value and the corresponding target value as coordinate axes._H, O_H)-(255,255)Correction curveBased on the captured RGBValue I _H (R) , I _H (G) , I _H (B)And then the RGB value I of the black section_L(R), I_L(G), I_L(B) is read and (0,0)-(I) in a two-dimensional graph having the read value and the corresponding target value as coordinate axes._L, O_L)-(255,255)Correction curveBased on the aboveCapturedRGBValue I _L (R) , I _L (G) , I _L (B)And then the RGB value I of the gray section_M(R), I_M(G), I_MRead (B),The target RGB value of gray is O _M (R) , O _M (G) , O _M (B) AsO '_MTo calculate
    O '_M(R) = ΣI_M+ (O_M(R) / ΣO_M)
    O '_M(G) = ΣI_M+ (O_M(G) / ΣO_M)
    O '_M(B) = ΣI_M+ (O_M(B) / ΣO_M)
(However, ΣI_M= I_M(R) + I_M(G) + I_M(B), ΣO_M= O_M(R) + O_M(G) + O_M(B))
  (0,0)-(I) in a two-dimensional graph having the read value and the corresponding target value as coordinate axes._M, O '_M)-(255,255)Correction curveBased on the aboveIs capturedRGBValue I _M (R) , I _M (G) , I _M (B)To achieve the above object.
  Claim3The invention comprises a sheet-like base material such as paper, resin film, etc., and has an adhesive layer that can be attached to a subject on the back side, the base material surface is mat-like, and the base material surface has at least A process of sticking an image recording color chart in which three color materials are applied to different sections in a mat shape to the subject by the adhesive layer and photographing the subject together with the subject, and storing the photographed image as digital data A process of displaying digital data captured in the storage device on a display, and a process of reading color values of the color chart for image recording on the display of at least two of the three colors. The correction value for each color is obtained from the digital data of the color value of the read color chart and the target value in the corresponding section in the color chart for image recording. And a step of correcting the digital data captured in the storage device by the calculated correction value and importing it again into the storage device, and the target values of the color values of the three colors are set in advance. A color correction method that sets and reads the color value of each section in the image on the display and calculates a correction value from the digital data of the read color value and the target value, wherein the color material is white, Black, gray, and the target value O of these color values_H, O_L, O_MIs set in advance, and the white and black sections of the image opened on the display are set to L^*Value I_H(L), I_L(L) and L in gray section^*a^*b^*Value I_M(L), I_M(a), I_M(b) is read, and (0,0)-(I) in a two-dimensional graph having the read value and the corresponding target value as coordinate axes._L(L), O_L(L))-(I_M(L), O_M(L))-(I_H(L), O_H(L))-(100, 100) through each pointCorrection curveBased on the captured L^*Convert data(However, the target for white, black and gray is L ^* Value O _H (L) , O _L (L) , O _M (L) And target a ^* Value, b ^* Value O _M (a) , O _M (b) And)Next, the correction values ΔM (a) and ΔM (b) are calculated by the following equations,
ΔM (a) = O_M(a) -I_M(a)
ΔM (b) = O_M(b) -I_M(b)
The correction values ΔM (a) and ΔM (b) are already taken in a^*And b^*Each is added to the data and the convertedL ^* DataSaveColor correction method characterized byThe above object is achieved.
Claim4The invention of claim 1 to claim 13In any of the above, the process of storing the correction value, the process of correcting the digital data of the image captured after the next time with the stored correction value, the process of storing the corrected digital data, It is made to have.
[0013]
  Claim5The invention of claim 1 to claim 14In any one of the inventions, the section to which the color material is applied is a grid having the same number as the number of types of the color material, and the substrate surface has the same dimensions surrounding the grid-shaped section. A scale is formed by arranging squares in rows.
[0014]
  Claim6The invention of claim 1 to claim 14In any one of the inventions, the substrate surface is square, a circle substantially inscribed in the square is formed on the substrate surface, and the circle is divided into four at a central angle of 90 °. Color material of any of the three primary colors of the RGB color system, the three primary colors of the CMY color system, and the basic color of the Lab color system in one of the four corners of the square outside the circle and the circle, On the other hand, at least one of white, gray and black color materials is applied.
[0015]
  Claim7The invention of claim6In this invention, the whole area of the square on the surface of the base material is divided into squares so as to overlap the quadrant of the circle.
[0016]
  Claim8The invention of claim6In the invention, at least one quadrant in the circle on the surface of the base material is superposed on the quadrant of the circle and partitioned into squares.
[0017]
  Claim9The invention of claim5Thru8In any one of the inventions, the length of one side of each of the grid-like sections is the same dimension.
[0018]
  Claim 10The invention of claim5Thru9In any one of the inventions, the surface of the base material is made of a material having irregularities and colors substantially equal to the surface of the subject.
[0019]
  Claim 11The invention of claim5Thru9In any one of the inventions, the surface of the base material is made of a material having irregularities and colors substantially equal to human skin.
[0030]
In this invention, the color chart for image recording is composed of a sheet-like base material that can be attached to a subject, for example, the skin of a human body, and the surface of the base material is a mat shape that suppresses reflection of light. At least three color materials are applied in a mat shape to different sections on the surface, so that after the subject is photographed, color correction is accurately performed based on the three colors, and color images of different subjects are recorded. Color image recordings under different conditions can be accurately compared.
[0032]
  In addition, color material is applied to the grid-like sections and around it.SameBy arranging the squares with dimensions in rows, the scale can be configured so that not only the color but also the size, inclination, and distortion of the subject can be accurately known and adjustment can be facilitated.
[0033]
  Also, make the surface of the base material square and its inscribed circleCenter angle 90 °Divide into four equal parts, and apply appropriate color materials to the four corners of the quadrant and the outer square, so that colors are optimally arranged according to conditions such as the type of subject, image output mode, etc., and correction and comparison Can be made easy.
[0034]
Furthermore, the entire surface of the base material is partitioned into squares so as to overlap with the quadrant of the circle, so that dimensions and distortion can be expressed more accurately and correction can be facilitated.
[0035]
  Furthermore, the length of one side of each square-shaped section is set toSameBy making the dimensions, the size of the subject can be understood at a glance.
[0036]
In addition, the surface of the base material is made of a material having substantially the same unevenness and color as that of the subject, for example, human skin, so that the reflection of light on the surface of the subject and the condition of the color tone can be accurately reflected to perform later image processing. Can be done accurately.
[0037]
According to the present invention, the color value on the display and the correspondence in the color chart of at least two of the basic three colors (three colors in the case of RGB and CMY) in the image display color chart captured as an image By comparing the color values of the color materials in the sections to be calculated and calculating the correction value for each color, the values in the sections of each color in the image can be easily corrected so as to be optimal for the entire image.
[0038]
Also, since the color of the section of the image to be read is white, black and gray and these color values are corrected simultaneously, the result of the previous correction is not affected by the subsequent correction, and the color value Can be optimized. In addition, it is possible to easily correct a color tone defect caused by overexposure or underexposure when photographing a subject.
[0039]
In addition, the color of the section to be read is set to white, black, gray, and in this order, and the color value is corrected each time reading is performed, which is caused by overexposure and color cast when photographing the subject. It is possible to easily correct poor color tone. When reading and correcting in order of white, black, and gray, the best correction result was obtained.
[0040]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0041]
  As shown in FIG. 1, an image recording color chart 10 according to the present invention comprises a sheet-like base material 12 such as paper or a resin film, has a square surface shape, and a square cell having nine squares in the center. Colored section 14 formed in an eye shape, and smaller than color section 14 around itSameA scale 16 is provided in which squares of dimensions are arranged in rows.
[0042]
The nine color sections 14 are R, G, B, which are three primary colors of light, and black, gray, white, and Y, which are three primary colors of coloring materials, from the upper left to the lower right in FIG. , M, and C.
[0043]
The surface of the sheet-like substrate 12 is mat-like (matte), and the finish of the color material to be applied (printed) is mat-like so that reflected light is scattered.
[0044]
Further, as shown in an enlarged view in FIG. 2, the back side of the sheet-like substrate 12 is an adhesive layer 18 that can be attached to a subject such as human skin, for example, and is attached to a mount 19 made of release paper, for example. It is attached so that it can be peeled off from the mount 19 for use.
[0045]
For example, as shown in FIG. 3, the color chart 10 for image recording is attached to the face of the patient 20 with an adhesive layer 18, and a photograph or video is taken with the adhesive layer 18 attached.
[0046]
The color of an image recorded (photographed) on a film or a magnetic recording device naturally varies depending on conditions such as illumination light, film, camera, etc., but the color of the image recording color chart 10 is included in the recorded image. Therefore, if the image processing device (computer) corrects each color of the color section 14 so as to restore the original color, the skin color of the patient 20 is accurately corrected.
[0047]
Furthermore, since the three primary colors RGB of light, the three primary colors CMY of color materials, and white, gray and black for color balance adjustment are applied to the color section 14, it is possible to correct accurately according to the output form of the color image. it can.
[0048]
Further, since the scale 16 is also captured in the recorded color image, the size of the color image recorded under a plurality of different conditions can be adjusted equally based on the scale 16. Further, since both the color section 14 and the scale 16 are square grids, it is possible to accurately know the inclination and distortion state of the subject.
[0049]
A specific procedure for obtaining a digital signal for image processing is as follows.
[0050]
First, when shooting with a still camera, the image of the film or photographic paper is disassembled with a color scanner and converted into digital data. When the image is taken with a digital camera, the signal is processed as it is. Furthermore, when the image is taken with a video camera, the still image is A / D converted into a digital signal, which is processed by an image processing apparatus to be corrected (details will be described later).
[0051]
The image recording color chart 10 is prepared, for example, in a plurality of types such as 5 cm, 2 cm, 1 cm, and 5 mm in length of one side, and is used according to the size of the subject. For example, when imaging a patient's face as shown in FIG. 3, a square image recording color chart 10 having a side of 1 cm or 2 cm is used.
[0052]
In this case, the area of the color chart 10 for image recording is not excessive with respect to the total area of the obtained color image, and is not excessively small so that sufficient color information can be obtained during image processing, for example, a color image Of 1/50 to 1/100 of the area.
[0053]
Note that, in the color chart for image recording having a side of 5 mm, the grids of the scale 16 are crushed in the color image, so that they are the same as the grids of the color section 14 as shown in FIG. 4, for example. .
[0054]
In the example of FIG. 1 described above, the surface of the sheet-like base material 12 is divided into grids to form color sections 14, and a scale 16 is formed on the outside thereof. However, the present invention is not limited to this. The color material is not limited to RGB and CMY colors, and the basic color of the Lab color system may be used as long as at least three color materials are applied to different sections on the surface of the sheet-like substrate. (Hereinafter, referred to as basic colors including the three primary colors of RGB and CMY) may be used. Therefore, the following various embodiments may be used.
[0055]
  The color chart 22 for image recording according to the second example of the embodiment of the present invention shown in FIG. 5 has a square surface, and the inscribed circle 24 and the four corners of the square outside the square. In addition, a color section 26 for displaying three or four basic colors of RGB, CMY, or Lab is provided, and an inner side of the inscribed circle 24 is provided.Center angle 90 °It is divided into four equal parts, and square squares 28 are formed so as to overlap the quadrant line 24A, and two opposing quadrant circles 25 are black.
[0056]
When three basic colors of RGB are applied to the color section 26, the remaining corner may be gray. Further, the lines of the cells 28 in the pair of quadrants 25 made black are uncolored.
[0057]
The quadrant in the inscribed circle 24 may not be applied to black as in the image recording color chart 30 of the third embodiment of FIG.
[0058]
Further, FIG. 7 shows an image recording color chart according to a fourth example of the embodiment of the present invention.
[0059]
This color chart 32 for image recording partitions the entire area of the square surface by a grid 34, forms an inscribed circle 36 inscribed in the square, and further superimposes the inscribed circle 36 on the square 34. A color material obtained by dividing an equal line 36A into four equal parts and adding one color to the three basic colors of the RGB color system, the CMY color system, and the Lab color system in the quadrant 37. The four corners between the inscribed circle 36 and the square are appropriately colored in white, gray, and black.
[0060]
The color chart 40 for image recording of the fifth embodiment of the present invention shown in FIG. 8 is used when the image processing apparatus performs color correction on one 25A of the quadrant 25 in the embodiment shown in FIG. A particularly important color material is applied. In this case, as shown in FIG. 8 (A), the squares in the quadrant 25 may be removed, and as shown in FIG. 28 may be provided.
[0061]
FIG. 9 shows an image recording color chart 42 according to a sixth example of the embodiment of the present invention.
[0062]
This color chart 42 for image recording is the same as the scale 16 in FIG. 9, but in the right vertical column in FIG. 9, unfilled white cells 44A to 44E every other square from the upper end and each white cell. It is composed of information display cells 46A to 46D which are filled or not painted according to the version number which is one of the color chart management information between the cells 44A to 44E.
[0063]
Further, in FIG. 9, the lower horizontal row in the scale 16 includes white squares 45 </ b> A to 45 </ b> E that are not filled and every other square from the right end, and between these white squares 45 </ b> A to 45 </ b> E. The information display cells 47A to 47D are filled or not filled corresponding to the lot number which is one of the color chart management information.
[0064]
The two squares at the center of the upper horizontal row in FIG. 9 of the scale 16 are each half-filled to form an upward arrow-shaped sticking direction indication mark 48.
[0065]
The information display cells 46A to 46D and 47A to 47D display a version number and a lot number in binary.
[0066]
For example, as shown in FIG. 9, when only the first information display cell 46A from the top in the vertical direction column is filled, the version number. 1 and when the first and second information display cells 46A and 46B are filled as shown in FIG. 3 and when the first, third and fourth information display cells 46A, 46C and 46D are filled as shown in FIG. 13 is displayed.
[0067]
In the lower horizontal row, for example, as shown in FIG. 9, when only the first information display grid 47A is filled, the lot No. 1 and when only the second information display grid 47B is filled as shown in FIG. 2 and when the first, second and third information display cells 47A, 47B and 47C are respectively filled as shown in FIG. 7 is displayed.
[0068]
The color value of each color in the color section 14 in the image recording color chart 42 is measured in advance for each version number and lot number, and is recorded as a table in a computer memory or paper. The color value can be set and / or displayed by reading or specifying. Alternatively, a table (table) describing each color value for the lot number may be prepared in advance, and the color value of the table may be manually input to the computer.
[0069]
In the above embodiment, the surface of a sheet-like base material such as paper or resin film is formed in a mat shape, and color materials such as three basic colors are applied in a mat shape here. Reflection by light is to prevent the generation of an unclear image such as a color flicker, and ideally, the surface should have a property that matches the irregularities and colors of the surface of the subject.
[0070]
Therefore, for example, when the image recording color chart according to the present invention is applied to the human skin, the surface of the base material of the image recording color chart is substantially the same as the unevenness and color of the human skin. It is good.
[0071]
The unevenness of the human skin is appropriately selected according to, for example, infants, children, adults, elderly people, men, women, oily skin, and dry skin. Furthermore, colors shall be arranged according to white race, yellow race, black race or mixed race of these.
[0072]
Next, an example of a method for actually correcting the color of an image using the image recording color chart as described above will be described.
[0073]
In this method, as shown in FIG. 12, the color chart for image recording as described above is attached to the patient 20 as the subject by the adhesive layer 18, and is photographed together with the patient 20. The process of capturing an image as digital data into the storage device 51 of the computer 50 shown in FIG. 13, the process of displaying the digital data captured in the storage device 51 on the display 52, and at least two of the three colors The process of instructing the color value of the color chart on the display 52 by, for example, the pointing device 54 and taking it into the chart value reading unit 55, the digital data of the color value of the read color chart and the correspondence in the color chart for image recording By comparing the target value (set in advance) or the set value in the section For example, the correction value for each color is calculated in the correction curve creation unit 56, and the digital data captured in the storage device 51 is corrected by, for example, the image data conversion unit 58 based on the calculated correction value. The image color correction method using the color chart is configured by the process of taking in the storage device 51. Reference numeral 60 denotes the entire image correction unit, and 62 denotes a target value setting unit. The target value or set value is a target value setting unit based on a table input in advance by reading or inputting the same version number and lot number as in the color chart for image recording shown in FIGS. In 62, it is set automatically. As described above, the target values shown in the table may be manually input to the target value setting unit 62 and set.
[0074]
Specifically, as shown in FIG. 12, an image recording color chart is attached to the patient 20 as a subject in step 101, the subject is photographed together with the color chart in step 102, and the photographed image is digitized in step 103. The image stored in step 104 is displayed on the display 52. In step 105, the color values of the white, black, and gray sections in the color chart image on the display 52 are read by the scanner 54.
[0075]
Next, as shown in FIG. 14, the correction curve creation unit 56 uses the read digital data and digital data of preset target values of white, black, and gray in the color chart for image recording as shown in FIG. 14. Then, a correction curve is formed in a two-dimensional graph with the correction value as the vertical axis and the read value as the horizontal axis (see step 106), and the captured digital data is corrected based on the correction curve (see step 107). The digital data corrected in step 108 is stored.
[0076]
More specifically, as shown in FIG. 13, the target value setting unit 62 causes the correction curve creation unit 56 to preliminarily set the target values O, W, G, and G._H, O_L, O_MAfter the image is opened on the display 52, the RGB values I of the white, black, and gray sections in the image are set._H(R), I_H(G), I_H(B), I_L(R), I_L(G), I_L(B), I_M(R), I_M(G), I_M(B) is read, and the point (0,0) − (I_L, O_L)-(I_M, O_M)-(I_H, O_H)-(255, 255) is formed, RGB digital data that has already been captured is converted based on the correction curve, and the digital data is stored in the storage device 51.
[0077]
For example, the RGB value (input value) of the color chart for image recording is
White: I_H(R) = 208, I_H(G) = 188, I_H(B) = 217
Black: I_H(R) = 29, I_H(G) = 16, I_H(B) = 19
Gray: I_H(R) = 126, I_H(G) = 90, I_H(B) = 138
The target RGB value (target value) is
White: O_H(R) = O_H(G) = O_H(B) = 228
Black: O_L(R) = O_L(G) = O_L(B) = 35
Gray: O_M(R) = O_M(G) = O_M(B) = 114
in the case of,
The correction curve is
R data: (0,0) − (29,35) − (126,114) − (208,228) − (255,255)
G data: (0,0)-(16,35)-(90,114)-(188,228)-(255,255)
B data: (0,0)-(19,35)-(138,114)-(217,228)-(255,255)
(See FIG. 14).
[0078]
Assuming that the correction algorithm 1 in the flowchart 1 shown in FIG. 12 is the correction algorithm 1, the correction algorithm 1 simultaneously corrects and converts the read digital data of each of the white, black, and goo color sections. This is ideal because there is no drawback that the result of the correction performed earlier is influenced by the row correction later, as in the case of correcting sequentially for each gray.
[0079]
However, if it is difficult to take the correction method of algorithm 1 due to the computer configuration or software specifications, the following correction methods such as correction algorithms 2 to 4 may be used.
[0080]
These algorithms 2, 3 and 4 correct the digital data taken in by the procedure of the flowchart shown in FIG.
[0081]
First, the correction algorithm 2 will be described with reference to FIG.
[0082]
Preliminary white, black and gray target values O_H, O_L, O_MIs set, the image is displayed in step 201, and the RGB value I of the white section in the image is displayed in step 2._H(R), I_H(G), I_H(B) is read and the correction algorithm (0,0)-(I_H, O_H)-(255, 255) to create a highlight correction curve (see FIG. 16). Next, with this highlight correction curve, each RGB data is converted so as to perform highlight correction in step 204, and then In step 205, the RGB value I of the black section in the image_L(R), I_L(G), I_L(B) is read and in step 206 (0,0)-(I_L, O_L)-(255, 255), a shadow correction curve is created, and RGB data are converted so as to perform shadow correction in step 207.
[0083]
Next, the RGB value I of the gray section in the image_M(R), I_M(G), I_M(B) is read and in step 209 (0,0)-(I_M, O_M)-(255, 255) is created, and based on this, each RGB data is converted so as to perform gray correction, and the image (digital data) is stored in step 211.
[0084]
For example, the RGB value (input value) of the chart is
White: I_H(R) = 208, I_H(G) = 188, I_H(B) = 217
Black: I_H(R) = 29, I_H(G) = 16, I_H(B) = 19
Gray: I_H(R) = 126, I_H(G) = 90, I_H(B) = 138
The target RGB value (target value) is
White: O_H(R) = O_H(G) = O_H(B) = 228
Black: O_L(R) = O_L(G) = O_L(B) = 35
Gray: O_M(R) = O_M(G) = O_M(B) = 114
in the case of,
The highlight correction curve is
R data: (0,0)-(208,228)-(255,255)
G data: (0,0)-(188,228)-(255,255)
B data: (0,0)-(217,228)-(255,255)
The shadow correction curve is
R data: (0,0)-(29,35)-(255,255)
G data: (0,0)-(16,35)-(255,255)
B data: (0,0)-(19,35)-(255,255)
The gray correction curve is
R data: (0,0)-(126,114)-(255,255)
G data: (0,0)-(90,114)-(255,255)
B data: (0,0)-(138,114)-(255,255)
(See FIGS. 16 to 18).
[0085]
The correction algorithm 3 is different from the correction algorithm 2 in the steps 209 and 210. Step 209 in the correction algorithm 3 is the RGB value I of the read gray section._M(R), I_M(G), I_MAverage value of (B) Ave (I_M) To calculate (0,0) -I_M, Ave (I_M)-(255, 255), a gray correction curve is created, RGB digital data is converted based on the correction curve in step 210, and the digital data of the image converted in step 211 is stored.
[0086]
The RGB value (input value) of the chart is
White: I_H(R) = 208, I_H(G) = 188, I_H(B) = 217
Black: I_H(R) = 29, I_H(G) = 16, I_H(B) = 19
Gray: I_H(R) = 126, I_H(G) = 90, I_H(B) = 138
The target RGB value (target value) is
White: O_H(R) = O_H(G) = O_H(B) = 228
Black: O_L(R) = O_L(G) = O_L(B) = 35
in the case of,
The highlight correction curve is
R data: (0,0)-(208,228)-(255,255)
G data: (0,0)-(188,228)-(255,255)
B data: (0,0)-(217,228)-(255,255)
The shadow correction curve is
R data: (0,0)-(29,35)-(255,255)
G data: (0,0)-(16,35)-(255,255)
B data: (0,0)-(19,35)-(255,255)
The gray correction curve is
R data: (0,0)-(126,118)-(255,255)
G data: (0,0)-(90,118)-(255,255)
B data: (0,0)-(138,118)-(255,255)
(See FIGS. 16 to 18).
[0087]
Next, the correction algorithm 4 will be described.
[0088]
This correction algorithm is the same as the correction algorithm 2 in steps 201 to 208. In step 209, O '_MIs calculated.
[0089]
O '_M(R) = ΣI_M* (O_M(R) / ΣO_M)
O '_M(G) = ΣI_M* (O_M(G) / ΣO_M)
O '_M(B) = ΣI_M* (O_M(B) / ΣO_M)
[0090]
Further calculated O '_M(0,0)-(I_M, O '_M)-(255, 255) is created, RGB digital data is converted based on the gray correction curve in step 210, and the digital data of the image converted in step 211 is stored It is.
[0091]
Similarly, the RGB value (input value) of the chart is
White: I_H(R) = 208, I_H(G) = 188, I_H(B) = 217
Black: I_H(R) = 29, I_H(G) = 16, I_H(B) = 19
Gray: I_H(R) = 126, I_H(G) = 90, I_H(B) = 138
The target RGB value (target value) is
White: O_H(R) = O_H(G) = O_H(B) = 228
Black: O_L(R) = O_L(G) = O_L(B) = 35
Gray: O_H(R) = O_H(G) = O_H(B) = 114
in the case of,
The highlight correction curve is
R data: (0,0)-(208,228)-(255,255)
G data: (0,0)-(188,228)-(255,255)
B data: (0,0)-(217,228)-(255,255)
The shadow correction curve is
R data: (0,0)-(29,35)-(255,255)
G data: (0,0)-(16,35)-(255,255)
B data: (0,0)-(19,35)-(255,255)
The gray correction curve is
R data: (0,0)-(126,118)-(255,255)
G data: (0,0)-(90,118)-(255,255)
B data: (0,0)-(138,118)-(255,255)
(See FIGS. 16 to 18).
[0092]
Since the correction algorithms 2, 3 and 4 are performed in the order of white, black, and gray, that is, highlight correction, shadow correction, and gray correction are performed independently, the result of the previous correction is affected by the subsequent correction. There is no major inconvenience in practice.
[0093]
Further, as described above, in the correction algorithms 2, 3, and 4, when correction is performed in the order of highlight (white), shadow (black), and gray, white may change due to subsequent correction of black and gray. Since the change in appearance is small, the best correction result was obtained.
[0094]
In the correction algorithms 1 to 4, RGB data is taken as an example of image data, but this may be CMY data.
[0095]
Next, L^*a^*b^*Or L^*u^*v^*, YIQ, etc., a correction algorithm 5 for color system image data in which brightness (luminance) and color difference are separated,^*a^*b^*Data will be described as an example with reference to the flowchart of FIG.
[0096]
Preliminary white, black and gray targets O_H, O_L, O_MIs set, and the image is displayed in step 301, and the white and black sections L in the image are displayed in step 302.^*Value I_H(L), I_L(L) and L in gray section^*a^*b^*Value I_M(L), I_M(a), I_M(b) is read, and in step 303 (0,0)-(I_L(L), O_L(L))-(I_M(L), O_M(L))-(I_H(L), O_H(L))-L through (100, 100)^*Create a correction curve, and in step 304, based on this correction curve,^*Data is converted, and correction values ΔM (a) and ΔM (b) are calculated by the following equation in step 305.
[0097]
ΔM (a) = O_M(a) -I_M(a)
ΔM (b) = O_M(b) -I_M(b)
[0098]
And a that has already been captured in step 306^*And b^*The correction values ΔM (a) and ΔM (B) are added to the data, and the digital data of the image converted in step 307 is stored.
[0099]
For example, the chart L^*a^*b^*The value (input value) is
White: I_H(L) = 84
Black: I_L(L) = 12
Gray: I_M(L) = 55, I_M(a) = 24, I_M(b) = -19
Target L^*a^*b^*The value (target value) is
White: O_H(L) = 93
Black: O_L(L) = 22
Gray: O_M(L) = 58, O_M(a) = 0, O_M(b) = 0
In the case of L^*The correction curve is
(0,0)-(12,22)-(55,58)-(84,93)
-(100, 100)
(See FIG. 20), the correction values ΔM (a) and ΔM (b) are
ΔM (a) = 0−24 = −24
ΔM (b) = 0 − (− 19) = 19
It becomes.
[0100]
In the correction algorithm 5, the image data is L^*a^*b^*As an example, this is L^*u^*v^*Alternatively, color system image data in which brightness (brightness) and color difference are separated may be used.
[0101]
In addition, the correction algorithms 1 to 5 all correct the color tone using white, black, and gray sections. However, these are the corrections for poor color tone due to poor exposure and color cast at the time of shooting. This is because it is most effective to use three colors.
[0102]
For example, it is not easy to determine which part of a photographed image is considered as a highlight or shadow, but if it is an image photographed with a color chart for image recording, the white part of the color chart is the highlight point. , You can see at a glance that the black part is the shadow point.
[0103]
In addition, for the correction of color cast, it is necessary to find the part that should be originally achromatic in the image. However, since white, black and gray are achromatic, it is possible to correct the color cast. It is valid.
[0104]
The above correction algorithm corrects the color tone using white, black, and gray sections in the image. However, the present invention is not limited to this, and other colors are used. You may do. Further, the order of correction is not limited.
[0105]
In the color correction method, a correction curve is created for each image displayed on the display to correct the color value. However, in the case of a plurality of images having the same shooting conditions, the same correction curve is used. Can be used.
[0106]
Therefore, in this case, the correction curve creation step in the flowcharts of FIGS. 12, 15 and 19 is omitted by using the correction curve created and saved at the first color correction operation, and the color correction operation is performed. Can be shortened.
[0107]
【The invention's effect】
Since the image recording color chart of the present invention is configured as described above, when color correction is performed by an image processing apparatus using a color image captured by photographing, at least three standard colors are captured in the color image. The color correction of the subject can be performed accurately based on the standard color. Further, distortion, size, and distortion can be corrected by using a combination of a color material application with a circle, square, or grid.
[0108]
The color correction method using the image recording color chart of the present invention has an effect that it is possible to easily correct a color tone defect caused by overexposure or underexposure at the time of photographing.
[Brief description of the drawings]
FIG. 1 is an enlarged plan view showing an image recording color chart according to a first example of an embodiment of the invention.
FIG. 2 is an enlarged cross-sectional view of the image recording color chart.
FIG. 3 is a surface view showing a state in which the color chart for recording the image is attached to a patient's face.
FIG. 4 is a plan view showing a modification of the image recording color chart.
FIG. 5 is an enlarged plan view showing an image recording color chart according to a second example of the embodiment of the present invention;
FIG. 6 is an enlarged plan view showing a color chart for image recording according to a third example of the embodiment of the present invention.
FIG. 7 is an enlarged plan view showing a color chart for image recording according to a fourth example of an embodiment of the present invention.
FIG. 8 is an enlarged plan view showing an image recording color chart according to a fifth example of the embodiment of the invention.
FIG. 9 is an enlarged plan view showing an image recording color chart according to a sixth example of the embodiment of the present invention;
FIG. 10 is an enlarged plan view showing a color chart for image recording according to a seventh example of the embodiment of the present invention.
FIG. 11 is an enlarged plan view showing an image recording color chart according to an eighth example of the embodiment of the present invention.
FIG. 12 is a flowchart showing a procedure for correcting an image by a color correction method using an image recording color chart according to the present invention.
FIG. 13 is a block diagram showing a system for carrying out the same color correction method.
14 is a diagram showing an RGB correction curve created by the color correction algorithm shown in the flowchart of FIG.
FIG. 15 is a flowchart showing another correction algorithm of the color correction method according to the present invention.
16 is a diagram showing a highlight correction curve created by the algorithm of the flowchart shown in FIG.
FIG. 17 is a diagram showing the shadow correction curve
FIG. 18 is a diagram showing the same gray correction curve.
FIG. 19 is a flowchart showing still another correction algorithm of the color correction method according to the present invention.
20 is a diagram showing a correction curve created by the algorithm of the flowchart shown in FIG.
[Explanation of symbols]
10, 22, 30, 32, 40 ... Color chart for image recording
12 ... Sheet-like substrate
14, 26 ... Color section
16 ... Scale
18 ... Adhesive layer
20 ... patient
24, 36 ... Inscribed circle
24A, 36A ... 4 lines
25, 37 ... 4 equally divided circles
28 ...
50 ... Computer
51. Storage device
52 ... Display
54 ... Pointing device
56 ... Correction curve creation section
58. Image data converter

Claims (11)

It consists of a sheet-like base material such as paper or resin film, and is provided with an adhesive layer that can be attached to the subject on the back side, the base material surface is mat-like, and at least three colors on the base material surface A process of sticking an image recording color chart in which a material is applied in a mat shape in different sections to a subject by using the adhesive layer, and a process of capturing the captured image as digital data in a storage device; A process of displaying digital data captured in the storage device on a display, a process of reading color values of the color chart for image recording on the display of at least two of the three colors, and a read color The correction value for each color is calculated based on the digital data of the color value of the chart and the target value in the corresponding section in the image recording color chart. And correcting the digital data fetched into the storage device by the calculated correction value and fetching it again into the storage device, and setting target values of the color values of the three colors in advance. A color correction method for reading a color value of each section in the image on the display and calculating a correction value from the digital data of the read color value and the target value,
White said colorant, black, and gray, and white and the target value O _H black color value, O _L is set in advance to, RGB value I _H of the white section of the image displayed on the display (R), I _H (G), I _H (B) are read, and (0,0) − (I _H , O _H ) − in a two-dimensional graph having the read values and the corresponding target values as coordinate axes. The captured RGB values I _H (R) , I _H (G) , I _H (B) are converted based on correction curves passing through the points (255, 255),
Next, the RGB values I _L (R), I _L (G), and I _L (B) of the black section are read, and (0, 0) in a two-dimensional graph having the read values and the corresponding target values as coordinate axes. _{- (I L, O L)} - based on the correction curve passing through the points of (255, 255), the captured and are RGB values _{I L (R), I L} (G), converting the I _L (B) And
Then the gray compartment RGB value _{I M (R), I M} (G), reads the _{I M (B), I M} (R) This is a reading, I _M of _{(G), I M (B} ) An average value Ave (I _M ) is calculated, and (0,0) − (I _M , Ave (I _M )) − (255,255) in a two-dimensional graph having the read value and the corresponding target value as coordinate axes. The color correction method is characterized in that the captured RGB values I _M (R) , I _M (G) , and I _M (B) are converted on the basis of a correction curve passing through each of the points. It consists of a sheet-like base material such as paper or resin film, and is provided with an adhesive layer that can be attached to the subject on the back side, the base material surface is mat-like, and at least three colors on the base material surface A process of sticking an image recording color chart in which a material is applied in a mat shape in different sections to a subject by using the adhesive layer, and a process of capturing the captured image as digital data in a storage device; A process of displaying digital data captured in the storage device on a display, a process of reading color values of the color chart for image recording on the display of at least two of the three colors, and a read color The correction value for each color is calculated based on the digital data of the color value of the chart and the target value in the corresponding section in the image recording color chart. And correcting the digital data fetched into the storage device by the calculated correction value and fetching it again into the storage device, and setting target values of the color values of the three colors in advance. A color correction method for reading a color value of each section in the image on the display and calculating a correction value from the digital data of the read color value and the target value,
White said colorant, black, and gray, and the target value O _H These color values, O _L, O _M may be set in advance, RGB values I white compartment of the displayed image on the display _H (R), I _H (G), and I _H (B) are read and (0,0) − (I _H , O _H ) in a two-dimensional graph having the read value and the corresponding target value as coordinate axes. -Convert the captured RGB values I _H (R) , I _H (G) , I _H (B) based on correction curves passing through the points (-255, 255),
Next, the RGB values I _L (R), I _L (G), and I _L (B) of the black section are read, and (0, 0) in a two-dimensional graph having the read values and the corresponding target values as coordinate axes. _{- (I L, O L)} - based on the correction curve passing through the points of (255, 255), the captured RGB value _{I L (R), I L} (G), and converts the I _L (B) ,
Next, the RGB values I _M (R), I _M (G), and I _M (B) of the gray section are read, and the target RGB values of gray are determined as O _M (R) , O _M (G) , and O _M. As (B) , O ′ _M is calculated by the following formula,
_{O 'M (R) = ΣI} M + (O M (R) / ΣO M)
_{O 'M (G) = ΣI} M + (O M (G) / ΣO M)
_{O 'M (B) = ΣI} M + (O M (B) / ΣO M)
_{(However, ΣI M = I M (R} ) + I M (G) + I M (B), ΣO M = O M (R) + O M (G) + O M (B))
And said target value corresponding to this reading in a two-dimensional graph and coordinate axes _{(0,0) - (I M,} O 'M) - based on the correction curve passing through the points of (255, 255), the captured image correcting method using the color chart and converting the are and are RGB values _{I M (R), I M} (G), I M (B). It consists of a sheet-like base material such as paper or resin film, and is provided with an adhesive layer that can be attached to the subject on the back side, the base material surface is mat-like, and at least three colors on the base material surface A process of sticking an image recording color chart in which a material is applied in a mat shape in different sections to a subject by using the adhesive layer, and a process of capturing the captured image as digital data in a storage device; A process of displaying digital data captured in the storage device on a display, a process of reading color values of the color chart for image recording on the display of at least two of the three colors, and a read color The correction value for each color is calculated based on the digital data of the color value of the chart and the target value in the corresponding section in the image recording color chart. And correcting the digital data fetched into the storage device by the calculated correction value and fetching it again into the storage device, and setting target values of the color values of the three colors in advance. A color correction method for reading a color value of each section in the image on the display and calculating a correction value from the digital data of the read color value and the target value,
White said colorant, black, and gray, and the target value O _H These color values, O _L, may be set to O _M beforehand, white compartment and the black compartment of the image held on the display Read the L ^* values I _H (L), I _L (L), and the L ^* a ^* b ^* values I _M (L), I _M (a), I _M (b) of the gray section, (0,0) − (I _L (L), O _L (L)) − (I _M (L), O _M (L)) − (I in a two-dimensional graph having the corresponding target value as a coordinate axis _{H (L), O H (} L)) - (100,100)
Based on the correction curve passing through each point, the L ^* data that has been captured is converted,
(However, the target L ^* values for white, black, and gray are O _H (L) , _OL (L) , and O _M (L) , and the target a ^* value and b ^* value are O _M (a ) , O _M (b) )
Next, the correction values ΔM (a) and ΔM (b) are calculated by the following formulas,
_{ΔM (a) = O M (} a) -I M (a)
_{ΔM (b) = O M (} b) -I M (b)
A color correction method, wherein the correction values ΔM (a) and ΔM (b) are respectively added to a ^* and b ^* data already taken in, and the converted L ^* data is stored . In any one of claims 1 to 3, the steps of storing the correction value, the digital data of the captured image to the next after the steps of the correction by the correction value, which is the storage, the corrected digital data And an image correction method using a color chart. 5. The section to which the color material is applied is defined in any one of claims 1 to 4 , and has the same number of grids as the number of types of color materials, and the substrate surface surrounds the grid-shaped sections. A color correction method, wherein a scale is formed by arranging squares having the same dimensions in a row. In any one of Claims 1 thru | or 4 , the said base-material surface is made into a square, and the circle | round | yen substantially inscribed in the said square is formed in this base-material surface, And this circle | round | yen is equally divided into four at a central angle of 90 degrees, Color material of one of the four primary corners of the square outside the circle and one of the quadrant circles, the three primary colors of the RGB color system, the three primary colors of the CMY color system, and the basic color of the Lab color system A color correction method, wherein at least one of white, gray and black color materials is applied to the other. 7. The color correction method according to claim 6 , wherein the entire square area of the surface of the base material is partitioned into squares so as to overlap the quadrant of the circle. The color correction method according to claim 6 , wherein at least one quadrant in the circle on the surface of the base material is divided into squares by being superimposed on a quadrant of the circle. In any one of claims 5 to 8, a color correction method characterized by the length of the grid-like side of each compartment were the same size. In any one of claims 5 to 9, wherein the substrate surface is substantially equal to irregularities and surface of the object, color correction method characterized in that it is constituted from the color of the material. In any one of claims 5 to 9, wherein the substrate surface is approximately equal irregularities with human skin, the color correction method which is characterized in that it is constituted from the color of the material.

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