JP2001285638A - Image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing method by which the gradation or color can be adjusted around a noted part of an image without having effect of adjustment onto other unintended parts. SOLUTION: After colors (C, M, Y) or the like to set a gradation correction function are designated, part of the image to be noted is designated, the density of the image is set to a peak density VP, an upper setting value VU and a lower setting value VL of the density are set, and the gradation correction function is generated from the data. Similarly the hue, lightness and saturation are obtained from the colors of the noted part and a color correction function is generated for each of them. Using the gradation correction function and the color correction function, gradation conversion in the desired density and color correction in desired colors in the image are conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing method for performing gradation conversion processing or color correction processing on an image.

[0002]

2. Description of the Related Art For example, in the field of printing and plate making, a color image recorded on a read original is electrically processed for the purpose of streamlining work processes, improving image quality, and the like.
2. Description of the Related Art An image reading / recording / reproducing system in which a film original plate or a printing plate composed of four plates of M, Y and K is prepared and a desired printed matter is obtained therefrom is widely used.

In this case, a color image read by a scanner device or the like is converted to C, M, and C in order to obtain a printed matter having a desired gradation or color tone for a target portion.
A gradation conversion process is performed for each color of Y and K, or
A color correction process is performed for each of the colors C, M, Y, and K.

[0004] More specifically, in the gradation conversion process, a process of converting the density of a color image into a density capable of obtaining a desired output halftone% is performed. A tone curve, which is an input density-output density conversion table used in this conversion processing, includes a highlight (HL) portion of a color image and a shadow (SD).
In the part and the middle (MD) part, the adjustment is performed according to the gradation correction coefficient set by the operator. However, since the tone curve is adjusted by correcting a tone correction function prepared for each of the HL, SD, and MD parts based on the tone correction coefficient, for example, H
Attempting to finely adjust the vicinity of a specific gradation between L and MD has a problem that the gradation of an unintended part also varies.

In the color correction processing, generally, C,
A correction intensity function centering on the six hues of M, Y, R, G, and B is prepared in advance, and each correction intensity function is corrected using a color correction coefficient set by an operator, thereby obtaining a desired color tone. I'm trying to get. However, when it is desired to adjust the color tone of a specific portion, there is a problem that the color tone of an unintended portion also changes because the correction intensity function is set centering on the above six hues. For example, when it is desired to adjust the skin color, the correction intensity function centering on the R and Y hues is corrected.
Alternatively, the hue of Y changes greatly. In addition, when it is desired to adjust cloudy green, the correction intensity function is usually set so that a color with high saturation is further corrected, so that green more vivid than cloudy green changes.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is possible to adjust a gradation or a color centering on a focused portion of an image. It is an object of the present invention to provide an image processing method in which portions not to be affected are not affected by adjustment.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a tone correction function which designates a target portion of an image whose tone is to be corrected, and uses the density of the image as a reference. Create Then, the preset gradation conversion characteristic is corrected by the gradation correction function, and the gradation conversion processing of the image is performed by the corrected gradation conversion characteristic. in this case,
It is possible to correct the tone conversion characteristics near the desired density.

The tone correction function is based on the density V
_P can be set as a peak density and a function having a spread specified by the density width W can be set. Also, if the focus point is more, the concentration V _P is the average value of the concentration of a plurality of target point may be set based on the density width W to the standard deviation σ of the concentration V _P of the plurality of focus points.

The tone correction function created as described above is stored for each density of a portion of interest, and a desired tone correction function is selected according to the density to correct the tone conversion characteristics. Can be.

Further, according to the present invention, a portion to be color-corrected is specified for a color image, and a color correction function is created based on the color of the image. Then, the color correction processing of the designated color is performed by the color correction function.

In this case, a color correction function can be set for each of hue, lightness, and saturation, and each can be corrected independently.

[0012] Note that the color correction function of the hue can be the hue H _P of observed part and peak is set as a function having a spread that is specified in a hue width H _W. The color correction function according to the brightness, the peak brightness L _P of the observed part,
It can be set as a function of the range specified by the lightness closing L _U. Further, the color correction function of the color saturation may be the saturation S _P output observed part and peak is set as a function of the range specified by the saturation closing S _U. The hue H _P , lightness L _P , and saturation S _P of these portions of interest can be set as an average value of a plurality of points of interest.

[0013]

FIG. 1 is a diagram showing an external configuration of an image reading / recording / reproducing system to which the present invention is applied. The system includes an input scanner 10 that reads a color image recorded on a read document, an image processing apparatus 20 that performs image processing including a gradation conversion process, a color correction process, and the like on the read color image, The processed color image is represented by C,
And an output device 30 for outputting as a film original of four colors of M, Y and K. The output device 30
Can be configured as a device for directly outputting a printing plate.

The image processing apparatus 20 displays a color image read by the input scanner 10 and displays various setup parameters for image processing, processing results, and the like. A keyboard 24 and a mouse 26 are provided for switching between the two.

FIG. 2 is a block diagram showing the configuration of an image processing circuit centered on the image processing apparatus 20 shown in FIG. The image processing apparatus 20 has an image memory 32 that stores density data C, M, and Y of three colors obtained by performing color separation on a color image by the input scanner 10.

A range adjustment circuit 34 is provided downstream of the image memory 32. As shown in FIG. 3, the range adjustment circuit 34 uses the image processing apparatus 2 in which the set HL density of the highlight (HL) and the set SD density of the shadow (SD) set by the operator are set in advance as a reference.
Primary conversion tables α _C , α _M , and α _Y for conversion into the internal HL concentration and the internal SD concentration of 0 are stored in the respective density data C,
Created for each of M and Y, the primary conversion tables α _C , α _M , α
Density data C, M, the range adjustment processing of Y performed by _Y.

A gradation conversion circuit 36, a signal selection circuit 37, and a color correction circuit 40 are provided downstream of the range adjustment circuit 34.

The tone conversion circuit 36 converts the tone of each density data C, M, Y supplied from the range adjustment circuit 34 into a set tone conversion so as to obtain desired halftone data C, M, Y. Conversion processing is performed according to a tone curve corresponding to the characteristic.
That is, the highlight (HL), the middle (MD), and the shadow (S) are determined based on the gradation correction coefficient set by the operator.
D) correcting the existing tone correction function for each density, newly generating a tone correction function for the target portion designated by the operator, and using the tone correction function with the tone correction coefficient set by the operator. The tone curves β _C , β _M , and β _Y of the density data C, M, and _Y are adjusted using these corrected tone correction functions (see the dotted lines in FIGS. 4 to 7). Using the tone curves β _C , β _M , and β _Y obtained, the tone conversion processing of each density data C, M, Y is performed. The converted density data C, M, and Y are supplied to a subsequent adder 42. The details of the gradation conversion process will be described later.

The signal selection circuit 37 includes density data C, M,
This circuit selects the maximum value and the minimum value from Y, and supplies them to the UCR circuit 38 and the K generation circuit 39.

The UCR circuit 38 performs an under color removal process (UCR = Under Color Removal) on each of the density data C, M, and Y supplied from the range adjustment circuit 34 to correct the density data C, M, and Y. The amounts ΔC, ΔM, and ΔY are calculated and added to the adder 42 as negative data. In this case, the correction amounts ΔC, ΔM, and ΔY can be obtained, for example, from the maximum and minimum values of the density data C, M, and Y selected by the signal selection circuit 37 and the UCR intensity set by the operator.

The K generation circuit 39 adjusts the density data C, M, and Y selected by the signal selection circuit 37 by the same processing as the density data C, M, and Y in the gradation conversion circuit 36 based on the minimum value. Tone curve β _K (Fig. 4
To density data K is generated according to the dotted line in FIG.

The color correction circuit 40 performs a process for setting the color tone of each of the density data C, M, and Y supplied from the range adjustment circuit 34 to a desired color tone. As shown in FIG. 2, the color correction circuit 40 converts the density data C, M, and Y into a hue H, a lightness L,
The correction amount ΔC of each of the density data C, M, Y, and K is calculated by using the HLS conversion circuit 44 for converting into the saturation S, and each color correction coefficient set by the operator from the hue H, the lightness L, and the saturation S. , ΔM, ΔY, and ΔK, a C correction amount calculation circuit 46, an M correction amount calculation circuit 48, a Y correction amount calculation circuit 50, and a K correction amount calculation circuit 52.

As shown in FIG. 8, the C correction amount calculating circuit 46 calculates each of C, M, Y, R, G and B from the hue H, lightness L and saturation S supplied from the HLS conversion circuit 44. Unit color correction amounts uc, um, uy, ur, ur, ug, ub, u for a unit hue and a unit hue specified by a portion of interest designated by the operator (hereinafter, this unit hue is referred to as D).
Unit color correction amount calculation circuits 54C, 54M, 54 for obtaining d
Y, 54R, 54G, 54B, and 54D, and the unit color correction amounts uc, um, uy, ur, ug, ub, u
d is added in the adder 56, so that the correction amount ΔC
Is required.

The unit color correction amount calculation circuit 54C calculates a correction intensity vh from the hue H using a hue direction correction intensity function corresponding to the hue of C.
A brightness / saturation direction correction strength calculation circuit 60 for calculating a correction strength va from the brightness L and the saturation S using a brightness / saturation direction correction strength function corresponding to the hue of C;
A multiplier 62 for multiplying h and va, and a correction intensity vr as a result of the multiplication are multiplied by a color correction coefficient set by an operator to obtain density data C for the hue of C.
And a multiplier 64 for calculating the unit color correction amount uc.
In the adder 56, the calculated unit color correction amount uc is
Other unit color correction amounts um, uy, ur, ug, ub, ud
Is added, the correction amount ΔC of the density data C is obtained.

As shown in FIG. 9, the existing hue direction correction intensity functions have peaks at the center of each of the six hues C, M, Y, R, G, and B, and gradually decrease symmetrically adjacent to each other. The correction intensity is set to be 0 at the center of each hue. The existing brightness / saturation direction correction intensity function is shown in FIG.
As shown in FIG. 11 and FIG. 11, the correction strength of the lightness L and the correction strength of the saturation S are (0, 0) and (1,
A straight line passing through 1) is set as a product of these.

The unit color correction amount calculation circuit 54D newly generates a hue direction correction intensity function and a lightness / chroma direction correction intensity function for the target portion specified by the operator, and these functions and the color correction set by the operator are generated. The unit color correction amount ud is calculated using the coefficient.

The M correction amount calculation circuit 48, the Y correction amount calculation circuit 50, and the K correction amount calculation circuit 52 are configured similarly to the C correction amount calculation circuit 46.
4M, 54Y, 54R, 54G, 54B, and 54D are configured in the same manner as the unit color correction amount calculation circuit 54C, and a description thereof will be omitted. The details of the color correction process will be described later.

The correction amounts ΔC, ΔM, ΔY, and ΔK of the density data C, M, Y, and K obtained by the color correction circuit 40 are converted by the adder 66 into density data C, M,
Y and K are added to the halftone conversion circuit 68 as density data C, M, Y, and K with adjusted gradation and color tone. The dot% conversion circuit 68 converts each of the density data C, M, Y, and K into dot% data according to the output characteristics of the output device 30 and supplies the data to the output device 30.

The schematic configuration and operation of the image reading / recording / reproducing system to which the present invention is applied have been described. Next, the gradation conversion processing and the color correction processing, which are features of the present invention, will be mainly described in detail.

The color image of the read document is input to the input scanner 1.
After being read by 0, it is stored in the image memory 32 as density data C, M, Y. The read color image is displayed on the display 22 once. The operator performs setting work of the set HL density of the highlight and the set SD density of the shadow on the displayed color image. The image processing apparatus 20 creates primary conversion tables α _C , α _M , and α _Y (FIG. 3) for converting the set highlight HL density and the set shadow SD density into the internal HL density and the internal SD density. Are set in the range adjustment circuit 34.

The density data C, M, and Y read from the image memory 32 are then converted by the range adjustment circuit 34 into the primary conversion tables α _C ,
According to α _M and α _Y (FIG. 3), internal HL concentration and internal SD
Conversion processing is performed based on the density.

Next, the range adjusted density data C,
M and Y are supplied to a gradation conversion circuit 36, a signal selection circuit 37, and a color correction circuit 40.

Here, the display 22 constituting the image processing apparatus 20 displays the read color image together with the read color image.
The tone curve setting screen shown in FIG. 12 is displayed. The operator adjusts the tone curve according to this screen.

First, the operator sets each density data C,
Existing tone cards preset for M, Y, K
Beave β_C, Β_M, Β_Y, Β_KSelect Note that each tone
Beave β _C, Β_M, Β_Y, Β_KIndicates the type of color image or operation
A plurality can be set according to the data preference.

Next, the selected tone curve β _X (β _C ,
β _M , β _Y , β _K ) highlight (HL), middle (M
D), a gradation correction coefficient g _Xw for correcting the gradation of each part of the shadow (SD) and any part of interest is set. In the following, X = C, M, Y, K, and w =
h, m, s, and d, respectively, and density data C, M,
It is assumed that they represent the gradation correction coefficients of the highlight (HL), middle (MD), shadow (SD), and target portion (Def) of Y and K. In this case, the gradation correction coefficient g
_Xw can be called from an unillustrated memory or the like as an existing coefficient, instead of being set by the operator.

[0036] Therefore, an example of a method of adjusting the tone curve beta _X below. First, the selected tone curve β _X before adjustment is plotted around the origin on the highlight side in FIG.
Is rotated clockwise by 45 °, and compressed by 1 / √2 in both the input density direction and the output density direction to create a new tone curve β _X ′. Next, for the new tone curve β _X ′, as shown in FIG. 14, the floor set for the highlight (HL), middle (MD), shadow (SD), and target portion (Def). The tone correction functions γ _h , γ _m , γ _s and γ _d are added, and (1)
A tone curve β _X ″ is obtained as in the equation.

Β _X ″ = β _X ′ + g _Xh γ _h + g _Xm γ _m + g _Xs γ _s + g _Xd γ _d (1) Here, the gradation correction function γ _d for the target portion (Def)
Can be set as follows.

That is, when the operator selects the “change” button on the screen shown in FIG. 12, a gradation correction function setting screen shown in FIG. 15 is displayed on the display 22. On this screen, the operator uses the mouse 26 to specify a target portion (a portion where + is displayed on the image). In this case, a plurality of points can be designated as the portion of interest. Alternatively, a predetermined range can be designated as an area by enclosing the area with a line. Next, when the button of “gradation / color correction” is selected, “gradation correction (C)”, “gradation correction (M)”, “gradation correction (Y)”, “gradation correction (L)” , A menu of "color correction" is displayed.

The case where the operator selects, for example, the menu of "gradation correction (Y)" will be described. “Gradation correction (Y)” is a menu for obtaining a gradation correction function γ _d . The operator designates a portion of interest with the mouse 26, and sets the desired density width W of the gradation correction function γ _{d to} the lower side. set value V _L and the intensity of the upper set value V _U I
_L and _IU are set.

The image processing apparatus 20, when the value P _Y density data Y of the observed part designated by the operator and the peak concentration V _P, the lower set value of the gradation correction function gamma _d V _L and the upper set value V _U is obtained as V _L = (1−W) · V _P (2) V _U = W + (1−W) · V _P (3) Using the parameters set or obtained as described above, the gradation correction function γ _d is set to (0,
0), ( _VL , _IL ), ( _VP , 1), ( _VU , _IU ),
It is set as a function passing through the five points (1, 0). This function can be obtained by approximation using a multi-order function, quasi-Hermitian interpolation, or the like. FIG. 16 shows that I _L = I _U = 0.
5 shows the gradation correction function γ _d when set to 5. The peak concentration V _P, instead of the value P _Y density data Y of the observed part, can be set to any value by the operator.

The operator estimates the shape of the gradation correction function γ _d set as described above, and if OK, selects the “register” button to perform registration processing. Incidentally, gradation correction function gamma _d, it is also possible to modify already peak concentration V _P that is registered, density width W, the intensity I _L, the I _U reads by selecting the button "read" . In this case, it is possible to omit the operation of designating the target portion with the mouse 26. In addition, a registration name is set at the time of registration of the gradation correction function γ _d , the registration name registered at the time of reading is displayed on a screen, a desired registration name is selected from the displayed registration name, and each corresponding registration name is selected. Parameters can also be read and used.

When the "gradation correction (L)" menu is selected, the density data C, M, Y values P _C ,
P _M, with P _Y, the peak concentration V _P, for _{example, V P = 0.3P C + 0.59P} M + 0.11P Y ... determined as (4), hereinafter the same way gradation correction function gamma _d Can be set.

On the other hand, if the specified plurality of points of interest moiety averages the concentration of each point of interest, and the average value and the peak concentration V _P. In addition, the standard deviation σ is obtained from each density and the average value, and parameters W _min and W _max having a relation of 0 <W _min ≦ W ≦ W _max <1 are set. = 3 calculated as _{(W max -W min) · σ} / V P + W min ... (5), below, it is possible to set the tone correction function gamma _d in the same manner. The parameters W _min and W _max are values for limiting the practical use area, for example, W _min = 0.2
5, _Wmax = 0.75 is set, but it can be held inside the system as an arbitrary parameter. If W> _Wmax , W = _Wmax .

Further, when the target portion is designated as a region, the gradation correction function γ _d can be set based on the average value of the densities of all the images included in the region.

The tone curve β _X ″ created as described above based on the equation (1) is expanded by 1 / √2 in both the input density direction and the output density direction, and then the counterclockwise direction in FIG. A new tone curve β _XN that can obtain the desired gradation conversion by rotating it 45 ° in the direction
Is obtained. Among the new tone curves β _XN , the tone curves β _CN , β _MN , and β _YN are set in the gradation conversion circuit 36, and the tone curve β _KN is set in the K generation circuit 39.

Therefore, the density data C, M, and Y supplied to the gradation conversion circuit 36 are converted into tone curves β _CN , β _MN , and β _YN
After being subjected to the respective tone conversions, they are supplied to the adder 42. In this case, it is possible to obtain density data C, M, and Y that have been subjected to gradation conversion at a desired density specified by the operator.

On the other hand, the UCR circuit 38
7, the correction amounts ΔC, ΔM, and Δ of the density data C, M, and Y are obtained from the maximum value and the minimum value of the density data C, M, and Y selected by the user and the UCR intensity set by the operator.
Y is calculated and added to the adder 42 as negative data.
Therefore, the density data C, M, and Y that have undergone the gradation conversion in the gradation conversion circuit 36 are corrected by the correction amounts ΔC, ΔM, and ΔY, and then supplied to the adder 66.

The K generation circuit 39 generates density data K based on the minimum value of the density data C, M, and Y selected by the signal selection circuit 37, and sets the density data K as described above. The tone is converted by the tone curve β _KN and supplied to the adder 66.

The gradation conversion is performed as described above, and the adder 6
The density data C, M, Y, and K supplied to the color correction circuit 6 are the correction amounts ΔC and ΔC calculated by the color correction circuit 40 described below.
It is corrected by M, ΔY, and ΔK and supplied to the dot% conversion circuit 68.

The processing in the color correction circuit 40 will now be described in detail.

The density data C, M, and Y whose range has been adjusted by the range adjustment circuit 34 are supplied to a color correction circuit 40, and are converted into hue H, lightness L, and saturation S in an HLS conversion circuit 44.

The hue H is 0 ≦ H <6, and the lightness L is 0 ≦ H <6.
L <1 and saturation S are set in the range of 0 ≦ S <1. Also,
H = 0 is R, H = 1 is Y, H = 2 is G, H = 3 is C, H
= 4 represents each hue of B, H = 5 represents each hue of M (see FIG. 9),
= 0 represents a dark color, L = 1 represents a bright color, S = 0 represents a cloudy color, and S = 1 represents a bright color.

In the HLS conversion circuit 44, the density data C,
A maximum value Q _max , an intermediate value Q _mid , and a minimum value Q _min of M and Y are obtained. Density data C, M, and Y that give the maximum value Q _max
max , the density data C, M, and Y giving the intermediate value Q _mid are P
_mid and density data C, M and Y giving the minimum value Q _min
Assuming that _min , V = (Q _mid −Q _min ) / (Q _max −Q _min ) (6) When P _max = Y and P _min = C, H = 1−V (7) When _Pmax = Y and _Pmin = M, H = 1 + V (8) When _Pmax = C and when _Pmin = M, H = 3-V (9) _Pmax = C, and , P _min = Y, H = 3 + V (10) P _max = M, and P _min = Y, H = 5-V (11) P _max = M and P _min = C Then, the hue H is obtained as H = 5 + V (12).

In the HLS conversion circuit 44, the lightness L
_Is obtained as L = 1−Q _max (13). If the color saturation S is Q _max ≦ 0, then S = 0 (14), otherwise, S = 1− (Q _min +0.1) / (Q _max +0.1) (15) ).

Next, the hue H, lightness L, and saturation S obtained as described above are used as the C correction amount calculation circuit 46, the M correction amount calculation circuit 48, the Y correction amount calculation circuit 50, and the K correction amount calculation. The correction amounts ΔC, ΔM, Δ
Calculation processing of Y and ΔK is performed.

In this case, a color correction screen shown in FIG. 17 is displayed on the display 22 constituting the image processing apparatus 20 together with the read color image. The operator performs a color correction operation according to this screen.

The operator selects an existing color correction function preset for each of the density data C, M, Y, and K by inputting a color correction number, and sets an existing color correction coefficient a _Xv . Recall and modify amounts ΔC, ΔM, Δ
Y and ΔK can be calculated. Note that X = C, M,
Y, K, v = c, m, y, r, g, b, d, and 6 hues C, C, M, Y, K, respectively.
It is assumed that they represent the color correction coefficients of the hues of M, Y, R, G, B and the portion of interest (Def).

Therefore, the process of calculating the correction amount ΔC according to FIG.
Will be explained. The color obtained by the HLS conversion circuit 44
The phase H is a hue type constituting the unit color correction amount calculation circuit 54C.
Input to the direction correction strength calculation circuit 58, as shown in FIG.
Hue direction correction intensity function F centered on the set hue C
_cThe hue correction intensity vh is obtained from (H). Also,
The brightness L and the saturation S are calculated by the unit color correction amount calculation circuit 54C.
The brightness / saturation direction correction strength calculation circuit 60
And set brightness / saturation direction correction intensity function G _c(L,
The lightness / chroma correction intensity va is obtained by S). this
Hue correction intensity vh and lightness / chroma correction intensity va
Is multiplied by the multiplier 62 and then multiplied by the multiplier 64.
Is the color correction coefficient a_CcIs multiplied, and the C hue correction intensity uc is
Is calculated. That is, the C hue correction intensity uc is given by: uc = F_c(H) · G_c(L, S) · a_Cc ... (16)

Similarly, the unit color correction amount calculation circuit 54
For M, 54Y, 54R, 54G, 54B, 54D, M hue correction intensity um, Y hue correction intensity ui, R hue correction intensity ur, G hue correction intensity ug, B hue correction intensity u
b and D which is the correction intensity of the hue of the portion of interest (Def)
The hue correction intensity ud is a hue direction correction intensity function F _v (H)
And the brightness / chroma direction correction intensity function G _v (L, S), respectively, are obtained as follows. Note that _v in the hue direction correction intensity function F _v (H) and the lightness / chroma direction correction intensity function G _v (L, S) is c, m, y,
r, g, b, d, and 6 hues C, M, Y, R, G, B
And the respective functions of the hue of the target portion (Def).

Um = F _m (H) · G _m (L, S) · a _Cm (17) ui = F _y (H) · G _y (L, S) · a _Cy (18) ur = F _r (H) · G _r (L, S) · a _Cr (19) ug = F _g (H) · G _g (L, S) · a _Cg (20) ub = F _b (H) · G _b (L, S) · a _Cb (21) ud = F _d (H) · G _d (L, S) · a _Cd (22) C hue correction intensity uc, M obtained as described above The hue correction intensity um, the Y hue correction intensity uy, the R hue correction intensity ur, the G hue correction intensity ug, the B hue correction intensity ub, and the D hue correction intensity ud are added by the adder 56 to obtain the density data C. The correction amount ΔC is calculated.

Here, the hue direction correction intensity function F _d (H) and the lightness / chroma direction correction intensity function G _d (L, S) for the hue D of the target portion can be set as follows. .

That is, when the operator selects the “change” button on the screen shown in FIG. 17, a modified intensity function setting screen shown in FIG. 18 is displayed on the display 22. On this screen, the operator uses the mouse 26 to specify a target portion (a portion where + is displayed on the image). In this case, a plurality of points can be designated as the portion of interest. Alternatively, a predetermined range can be designated as an area by enclosing the area with a line. Next, when the button of “gradation / color correction” is selected, “gradation correction (C)”, “gradation correction (M)”, “gradation correction (Y)”, “gradation correction (L)” , A menu of "color correction" is displayed. The operator selects “color correction” from this menu.

The image processing apparatus 20 has a
Hue H, lightness L, and saturation of the portion of interest specified by 26
S is obtained by the HLS conversion circuit 44, and the obtained hue H
Value H _CIs the peak hue H_PAnd the hue width H_W(0 <H_W<1)
Hue direction correction intensity function F_d(H)
As shown in FIG._P-H_W, 0), (H_P,
1), (H_P+ H_W, 0) by linear interpolation within the section
Set. Note that the hue direction correction intensity function F_d(H)
As with the other hue direction correction intensity functions shown in FIG. 9, 0 <H
It is a function defined cyclically in the range of <6. That
H_P-H_W<0 or H_P+ H_W> 6 places
In this case, for example, the hue direction correction intensity function F_r(H)
As described above, the hue direction correction intensity function F_d
(H) is set.

The hue direction correction intensity function F _d (H)
As shown in FIG. _{20, (H P -H W,} 0), (H P -
_{H W / 2,1), (H} P + H W / 2,1), (H P + H W,
The four points 0) may be set by linear interpolation within the section. Further, as shown in FIG. 21, using the shape factor A, it is also possible to set F _d (H) = A · (H−H _P ) ² +1 (23).

Further, the lightness L depends on the designated target portion (De
The value L _C of the lightness L of f) is defined as the peak lightness L _P , and the lightness end value L
The _u, as _{L u = 1-L C ...} (24), the lightness direction correcting intensity function g1 _d a (L), 22
, (0,0), (L _P , 1), (1, L _u )
Are set by linear interpolation within the section.

[0066] Further, the saturation S is a value S _C of saturation S of the specified observed part to a peak saturation S _P, saturation closing S _u, as _{S u = 1-S C ...} (25), The saturation direction correction intensity function g2 _d (L) is calculated as shown in FIG.
As shown _{in, (0,0), (S P} , 1), (1, S u)
Are set by linear interpolation within the section.

The brightness / saturation direction correction intensity function G _d (L,
S) is the brightness direction correction intensity function g1 _d (L) and the saturation direction correction intensity function g2 set as described above.
_{From d} (L), G _d (L, S) = g 1 _d (L) · g 2 _d (L) (26)

The peak hue H _P and the hue width H which are the parameters of the hue direction correction intensity function F _d (H) and the lightness / chroma direction correction intensity function G _d (L, S) set as described above. _W, peak luminosity L _P, lightness closing L _u, peak saturation S _P, saturation closing S _u is displayed as shown in FIG. 18. The operator operates the hue direction correction intensity function F _d (H) and the lightness / chroma direction correction intensity function G according to the display.
_d ) The shape of (L, S) is estimated, and if OK, the “registration” button is selected and registration processing is performed. In this case, a registered name can be set. Further, the hue direction correction intensity function F
_d (H) and the brightness / saturation direction correction intensity function G _d (L,
S) operating the "read" button to display the registered names already registered on the screen, selecting a desired registered name from the displayed registered names, and reading and correcting each parameter. Can also. In this case, it is possible to omit the operation of designating the target portion with the mouse 26.

When a plurality of points or a region of interest are specified, the processing is performed as follows.

The hue H is 0 to 6 indicating the same hue as 0 and 6.
It is a value that circulates in the range of 6. Therefore, the maximum value and the minimum value of the hue H of the pixels in the designated plural points of interest or the area are obtained, and the difference is defined as _HA . On the other hand, when the hue H is 3
After replacing the hue H of what the above H-6, the maximum value and the minimum value of the replaced hue H ', to the difference between H _B. Next, H _A and H _B are compared, and the maximum value and the minimum value when the smaller one is given are H _max and H _min . Next, an average value of the hue H or H 'is obtained. When the average value is negative, 6 is added to the value. The average value of the hue H obtained in this way and H _P. Further, the maximum value _Hmax and the minimum value _{Hmin
Therefore} , H _dif = H _max −H _min (27), and if H _dif > 2, it is determined that the plurality of hues H of the target portion are too far apart, and the process is stopped. Also, H
_{If dif} ≦ 2, then H _W = 0.5 · H _dif +0.5 (28), if H _W > 1, H _W = 1, and as described above, the hue direction correction intensity function F _{Find d} (H).

[0071] In the case of the lightness L is the average value of the lightness L and peak brightness L _P, also the maximum value of the lightness L as L _max, lightness closing _{L u, L u = (L} max -1 _{) · L P / (1-} L P) determined as +1 ... (29) determines the lightness direction correcting intensity function g1 _d (L) as described above.

[0072] Further, in the case where the saturation S is the mean value of the saturation S and the peak saturation S _P, also the maximum value of the saturation S S _max
, The saturation end value S _u is obtained as S _u = (S _max −1) · S _P / (1−S _P ) +1 (30), and as described above, the saturation direction correction intensity function g2 _d ( S) is obtained.

In the color correction circuit 40, the correction amount Δ for each of the density data C, M, Y, and K is
C, ΔM, ΔY, and ΔK are calculated. In this case, as for the correction amounts ΔC, ΔM, ΔY, and ΔK, desired corrections are made to the color of the target portion specified by the operator.

The correction amounts ΔC, ΔM, ΔY, ΔK
Is added to the gradation-converted density data C, M, Y, and K in an adder 66, and is then supplied to a dot% conversion circuit 68. In the dot% conversion circuit 68, the corrected density data C, M, Y, K are converted into dot% data, and the output device 3
Output to 0. In the output device 30, from the net% to C,
A film original plate or a printing plate of each of the M, Y, and K plates is created.

In the above description, one tone correction function γ _d , one hue direction correction intensity function F _d (H), and one lightness / chroma direction correction intensity function G _d (L, S) are set. However, the present invention is not necessarily limited to this. For example, a function is set for each of a plurality of target portions having different color gamuts, such as skin color and sky blue,
A gradation conversion process and a color correction process can also be performed. Specifically, in the setting of the tone curve shown in FIG.
A plurality of tone correction coefficient setting units (Def) are provided, and a “change” button is selected for each of the tone correction coefficient setting units (Def) to select each tone correction function γ.
After setting and registering _d , by performing a process of adding to the equation (1), each registered tone correction function γ _d can be independently superimposed and act. Similarly, in the color correction shown in FIG. 17, a plurality of color correction coefficient setting units (Def) are provided, and a “change” button is selected for each of the color correction coefficient setting units (Def) to select each hue direction correction intensity function F _d (H) and lightness. and saturation direction correcting intensity function G _d (L, S) after setting registering, by performing processing for adding the adder 56 shown in FIG. 8, each hue direction correcting registered intensity function F _d (H)
And the brightness / saturation direction correction intensity function G _d (L, S) can be independently superimposed and act.

[0076]

As described above, according to the present invention, a specific tone correction function can be set for the density of a focused portion of an image, so that a desired tone can be set for a desired density. Conversion can be performed. In addition, since a specific color correction function can be set for the color of the focused part of the image, only the desired color can be corrected without correcting the extraneous color.

[Brief description of the drawings]

FIG. 1 is a diagram showing an external configuration of an image reading / recording / reproducing system to which the present invention is applied.

FIG. 2 is a block diagram illustrating a configuration of an image processing circuit mainly including an image processing apparatus.

FIG. 3 is an explanatory diagram of a conversion characteristic between a set density and an internal density in a range adjustment circuit.

FIG. 4 is an explanatory diagram of a process of adjusting tone conversion characteristics on the highlight density side in the tone conversion circuit.

FIG. 5 is an explanatory diagram of a process of adjusting the tone conversion characteristic on the intermediate density side in the tone conversion circuit.

FIG. 6 is an explanatory diagram of a process of adjusting the tone conversion characteristic on the shadow density side in the tone conversion circuit.

FIG. 7 is an explanatory diagram of a process of adjusting the tone conversion characteristics in the vicinity of the density of the target portion in the tone conversion circuit.

FIG. 8 is a configuration block diagram of a C correction amount calculation circuit in the color correction circuit.

FIG. 9 is an explanatory diagram of a hue direction correction intensity function.

FIG. 10 is an explanatory diagram of a brightness correction intensity function.

FIG. 11 is an explanatory diagram of a saturation correction intensity function.

FIG. 12 is an explanatory diagram of a tone curve setting screen.

FIG. 13 is an explanatory diagram of the adjustment processing of the gradation conversion characteristic.

FIG. 14 is an explanatory diagram of a gradation conversion characteristic adjustment process.

FIG. 15 is an explanatory diagram of a setting screen of a gradation correction function for the density of a target portion.

FIG. 16 is an explanatory diagram of a tone correction function for correcting a tone conversion characteristic with respect to the density of a target portion.

FIG. 17 is an explanatory diagram of a color correction screen.

FIG. 18 is an explanatory diagram of a color correction adjustment processing screen for hue, lightness, and saturation of a target portion.

FIG. 19 is an explanatory diagram of a hue direction correction intensity function for a target portion.

FIG. 20 is an explanatory diagram of another embodiment of a hue direction correction intensity function for a target portion.

FIG. 21 is an explanatory diagram of another embodiment of a hue direction correction intensity function for a target portion.

FIG. 22 is an explanatory diagram of a brightness direction correction intensity function for a target portion.

FIG. 23 is an explanatory diagram of a saturation direction correction intensity function for a target portion.

[Explanation of symbols]

Reference Signs List 10 input scanner 20 image processing device 22 display 30 output device 34 range adjustment circuit 36 gradation conversion circuit 37 signal selection circuit 38 UCR circuit 39 K generation circuit 40 color correction circuit 44 HLS conversion Circuit 46 ... C correction amount calculation circuit 48 ... M correction amount calculation circuit 50 ... Y correction amount calculation circuit 52 ... K correction amount calculation circuit 54C, 54M, 54Y, 54R, 54G, 54B, 5
4D: unit color correction amount calculation circuit 58: hue direction correction intensity calculation circuit 60: lightness / chroma direction correction intensity calculation circuit 68: dot% conversion circuit

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H04N 1/46 H04N 1/46 Z

Claims (13)

[Claims] An image processing method for performing a tone conversion process on an image, wherein a step of designating a target portion of the image and a step of creating a tone correction function based on the density of the specified target portion Correcting the preset gradation conversion characteristic by the gradation correction function, and performing a gradation conversion process on the image using the corrected gradation conversion characteristic. Processing method. 2. A method according to claim 1, wherein the gradation correction function, since the concentration V _P of the observed part, density width W (0 <W <1) _{and, V L = (1-W} ) _{· V P V U = W +} (1-W) · V P obtained as a set value V _L, using a V _U, the set value V _L, the intensity of the V _U I _L, and I _U, (0,0 ), (V _L ,
_{I L), (V P,} 1), (V U, I U), an image processing method characterized by determining as a function passing through the five points (1,0). 3. The image processing method according to claim 1, wherein the density of the target portion is set as an average value of the densities of a plurality of target points. 4. A method according to claim 2, wherein the concentration V _P of the observed part is set as the average value of the concentration of a plurality of target point, the density width W, and the standard deviation σ of the concentration V _P , 0 <W _min <W _max <1, W = 3 (W _max −W _min ) · σ / V _P + W _min using parameters W _min and W _max. Image processing method. 5. The image processing method according to claim 1, wherein the gradation correction function is stored, and the stored gradation correction function is read and used. 6. The image processing method according to claim 5, wherein said read-out gradation correction function is modifiable. 7. The method according to claim 1, wherein the density of the target portion is calculated by a linear combination of the densities of the three primary colors C, M, and Y constituting the target portion. An image processing method comprising: 8. An image processing method for performing a color correction process on a color image, wherein a step of specifying a target portion of the color image and a step of generating a color correction function based on the color of the specified target portion And correcting the color specified by the color correction function. 9. The image processing method according to claim 8, wherein the color correction function is set for each of hue, lightness, and saturation of the color. 10. The method according to claim 9, wherein the color correction function relating to hue is the hue H of the portion of interest._P
And the hue width H_W(0 <H _W<1) and (H)_P−
H_W, 0), (H_P, 1), (H_P+ H_W, 0)
An image processing method characterized by interpolating and obtaining within a period. 11. The method according to claim 9, wherein the color correction function relating to lightness is the lightness L _P of the target portion.
And (0,0), using the brightness final value L _U obtained as L _U = 1−L _P ,
(L _P, 1), an image processing method characterized by determining by interpolation in a section of the three points (1, L _U). 12. The method of claim 9, wherein the color correction function of the saturation, the saturation S _P output the observed part
And (0, 0) using the saturation end value S _U obtained as S _U = 1−S _P ,
An image processing method characterized in that three points (S _P , 1) and (1, S _U ) are obtained by interpolation within a section. 13. The image processing method according to claim 8, wherein the color of the target portion is set as an average value of a plurality of target points.