JP3591862B2 - Image processing device - Google Patents

Description

【００１８】
図２において、操作部８からは前述のように操作パネルにより調整した調整量に応じた制御信号をＣＰＵ９に出力し、ＣＰＵ９は階調調整回路７に制御信号を出力する。階調調整回路７は各色及び濃度域別に設けられているＲＯＭから構成されている。そして、これらのＲＯＭには図３に示した調整特性及び表１に基づいて決定された出力値がテーブルとして用意されており、入力された濃度信号の値に応じて変換し、出力する。なお、各ＲＯＭ中で変換後の値が２５５を越えるものについてはすべて２５５にクリップさせてある。
【００１９】
図５に図４に示したように設定した場合の階調特性を示す。図中、破線Ｍで示したものが中濃度域の変調量を表し、破線Ｓで示したものが高濃度域の変調量を示している。実線はこれらの変調量を合成した変調特性を示している。
【００２０】
このように、本実施例においては、各濃度域別に調整特性を設定し、この調整特性に基づいて画像信号の濃度制御を行っているので、画像全体としてのバランスを損ねることなく濃度制御を行うことが可能になる。
【００２１】
また、本実施例における濃度域別の階調調整と、図１４に示した従来の階調調整（以下カラーバランス調整）とを両方行うような構成にしてもよい。この場合も各色ごとにカラーバランス調整特性をテーブルとして持っているＲＯＭを設けることにより実現できる。
【００２２】
図６はカラーバランス調整を行う場合における操作パネルの表示であり、調整量がＣが±０，Ｍが＋３，Ｙが−４，ＢＫが±０である場合を示している。図７は本実施例における階調調整回路７の構成例を示す図で、カラーバランス調整用のＲＯＭ７０１と濃度域別調整用のＲＯＭ７０２を有しており、各ＲＯＭの出力を加算器７０３にて加算して出力する。また、図８は本実施例の動作を示すフローチャートであり、以下図８を用いて本実施例の動作を説明する。
【００２３】
まず、操作パネルに図６のように表示され、ユーザは各色ごとに調整量を決定する（ステップＳ８０１）。そして調整量を決定後、更に濃度域別調整を行う場合は、操作パネルの右上に表示されている濃度域別調整の部分を押す（ステップＳ８０２）。すると、操作パネルは図４に示したように表示が変化し、こんどは濃度域別の調整を行うことが可能になる。そこでユーザは前述のように調整したい色を決定し（ステップＳ８０３）、次に各濃度域別の調整量を決定する（ステップＳ８０４）。以上のように構成することにより、まず、カラーバランス調整にて全体的な画像の濃度調整を行い、更に細かな調整を行いたい場合には各濃度域別の調整を行うことが可能になり、それほど細かい調整を必要としない一般のユーザにも使いやすくなる。なお、前述の通り、階調調整回路７の出力としては、カラーバランス調整による濃度調整と濃度域別の調整とを両方反映したことになるように構成されている。
【００２４】
次に、本発明の第２の実施例について説明する。図９は、低濃度域Ｈを＋８，中濃度域Ｍを−８，高濃度域Ｓを＋８と調整した場合の調整曲線示している。この場合は、図９の実線で示した調整曲線となるが、図より明らかなように不連続な階調調整となってしまう。特に、入力画像信号レベルが７０〜８５の部分において特性が右下がりになってこの部分で階調変化が反転してしまい、出力画像信号の特性としてソラリゼーション効果となり不自然な画像になってしまう。そこで、本実施例においては、このように操作パネルにて極端な階調調整が行われ、右下がりの特性になってしまった場合これをＣＰＵ９により判断し、操作パネルに“異常画像になります”と表示することにする。これによりユーザに対してこのような階調調整を行った場合に出力画像が不自然な画像であることを認識させることができる。
【００２５】
また、このような右下がり等の正常でない調整特性であるとＣＰＵ９が判断した場合は、図９における一点鎖線Ａのように装置側で右下がりをなくし、正常の調整特性になるように特性を変更することにすれば、ユーザの調整したい画像に最も近い形で正常な画像調整を行うことが可能になる。
【００２６】
また、調整特性が異常である場合に、異常画像である旨を表示した後装置の方で自動的に特性を補正してもよいかをユーザに判断させ、拒否した場合には再び調整をやりなおさせるようにしてもよい。
【００２７】
前述の動作をカラーバランス調整を含めた場合において図１０のフローチャートを用いて説明する。まず、図６に示した操作パネルの表示によりカラーバランス調整を行う（ステップＳ１０１）。次に、濃度域別の調整を行う場合はその表示部分を押して、濃度域別の調整を行うパネルに変更する（ステップＳ１０２）。そして、調整したい色を決定した後（ステップＳ１０３）、各濃度域別に調整量を決定する（ステップＳ１０４）。次に、ステップＳ１０４で決定された調整特性が正常かどうか判断し（ステップＳ１０５）、正常であればそのままの特性で変換し、出力する。
【００２８】
また、ステップＳ１０５にて調整特性が正常でないと判断された場合には、操作パネルに異常画像であることを表示する（ステップＳ１０６）。そして、調整特性を装置の側で自動的に変更するかどうかを操作パネルに表示し、ユーザは変更可である場合は、ＣＰＵ９により濃度域別ＲＯＭ７０２の読み出しアドレスを変更することにより前述のように正常の調整特性になるように特性を修正して出力する（ステップＳ１０７）。また、ステップＳ１０７にて装置側で特性変更を行うのをユーザが拒否したばあいは、調整量の変更を支持する旨を操作パネルに表示し（ステップＳ１０８）、ステップＳ１０４に戻る。
【００２９】
なお、前述の実施例においては、調整特性が異常である場合にメッセージを表示するように構成したが、これは、ユーザがそれと認識可能なものであればどんなものでもよく、たとえば、ブザー・チャイム等の音により知らせる、ＬＥＤ等の光により知らせるなどが考えられる。また、調整特性が異常である場合は表示を行った後装置の方で勝手に特性を補正する構成にしてもよい。
【００３０】
また、前述の実施例においては調整特性が異常である場合として曲線が右下がりのばあいを例にとったが、これ以外にも、例えば急激な濃度上昇（または下降）後にフラットになる場合などでも、同様な画質異常が認められる可能性があり、このような場合でも同様に警告することで異常画像をユーザに知らせることが可能になる。
【００３１】
次に、本発明の第３の実施例について説明する。前述の第１，第２の実施例においては、図３に示した調整特性に基づいて濃度調整を行っているが、この場合図１１の破線に示すように濃度を上げる場合と下げる場合とで、図中直線で示した未調整の状態に対して垂直方向における変調の度合い（直線に対する変調特性の角度）が異なってしまい、調整後の画質が劣化することが考えられる。これを避けるためには、図１１の実線で示したように、各濃度域において濃度を増減させる場合に、直線に対して対称に特性が変化していくように変調特性を設定することが望ましい。
【００３２】
そこで、本実施例では、変調特性として図１２に示すように、図３に示した調整特性とは異なる調整特性を新たに設定し、濃度を上げる場合と下げる場合とで図１１の直線に関して垂直方向に対称な調整特性となるように構成した。
【００３３】
このように調整特性を設定することにより、濃度を上げる場合と下げる場合とで濃度変化が対称になり、濃度調整後の画質が劣化することはない。
【００３４】
また、これと同様な考えで、図１３に示したように、未調整の状態から各濃度域別に垂直に変調量を決定することにより最終的な調整特性を設定するようにしてもよい。ただし、この場合には、調整特性の曲線を求めるために図１２に示した直線に対して新たに調整量を計算したのち、直線に対して加算し最終的な調整特性を求める必要がある。
【００３５】
このように、図１３に示した調整特性に基づいて濃度調整を行った場合でも前述の実施例と同様に濃度調整後の画質の劣化の心配がない。
【００３６】
なお、前述の実施例においては階調調整手段においてＲＯＭを用いたが、入力画像信号に対応した出力を行ういわゆるルックアップテーブル（ＬＵＴ）機能を有するものであればこれに限られるものではない。また、図３に示すような調整特性だけをＲＯＭに記憶しておき、これを各色別に用意して、外部の制御手段より表１に示す比率を入力して最後に加算するような構成でもよい。
【００３７】
【発明の効果】
本発明によれば、複数の濃度域に対して独立に調整度合いを設定できるので、全体としての画像のバランスを損ねない所望の濃度調整を指示することができる。
【図面の簡単な説明】
【図１】本発明の実施例であるカラー複写機の構成を示すブロック図である。
【図２】図１のカラー複写機における画像処理部の構成を示すブロック図である。
【図３】本発明の実施例における、調整特性の例を示す図である。
【図４】本発明の実施例における操作パネルの表示を示す図である。
【図５】階調調整回路において、各濃度域の調整特性を統合した調整特性を示す図である。
【図６】本発明における操作パネルの表示を示す図である。
【図７】本発明の実施例における階調調整回路の構成を示す図である。
【図８】本発明の実施例を説明するためのフローチャートである。
【図９】操作パネルにて設定された調整特性の他の例を示す図である。
【図１０】本発明の実施例を説明するためのフローチャートである。
【図１１】本発明の実施例における調整特性の他の例を示す図である。
【図１２】図１１に示した調整特性の各濃度域別の例を示す図である。
【図１３】本発明の実施例における調整特性の更に他の例を示す図である。
【図１４】従来技術を説明するための図である。
【符号の説明】
７ 階調調整回路
８ 操作部
９ ＣＰＵ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image processing apparatus and method for performing density adjustment according to a user's instruction.
[0002]
[Prior art]
Conventionally, as this type of device, for example, a color gradation adjusting device used for a color copying machine or the like is known. In such a tone adjusting device, the tone of each color is adjusted according to the characteristics shown in FIG. 14 for each of the input density signals.
[0003]
FIG. 14 is a diagram showing specific characteristics of gradation adjustment. Normally, color conversion is performed using linear characteristics indicated by b, but the user can adjust the gradation characteristics of each color according to his / her preference. By operating the operation panel or the like, the characteristics as shown in FIGS. 14A and 14C are set, and as a result, the gradation can be adjusted.
[0004]
[Problems to be solved by the invention]
However, in such a conventional adjusting device, when there are colors in the original having the same hue and different lightness, that is, colors having different densities in the same series of colors, the color is adjusted to match a relatively light color. When the balance adjustment is performed, the dark color also changes as a result, and there is a problem that the color cannot be adjusted as intended by the user.
[0005]
The present invention has been made in view of the above-described problems, and has as its object to enable desired density adjustment without impairing the balance of an image as a whole.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an image processing apparatus according to the present invention includes an operation unit that inputs a user instruction regarding an adjustment degree independently for a plurality of density ranges,
Setting means for setting an adjustment characteristic from an adjustment degree according to the density range,
An image processing apparatus having a density adjustment unit that performs density adjustment based on the set adjustment characteristics,
The plurality of density ranges overlap with adjacent density ranges,
The setting means, the density range from the maximum adjustment amount in a low-density adjustment of the width at a high density area is wide the maximum compared to the range determined for each degree of adjustment and the concentration range corresponding to the concentration zone the calculated, and sets the adjustment characteristics make corrections of inversion when the gradation change is reversed gradation changes a composite of modulation amount modulation amount of each.
[0007]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0008]
FIG. 1 is a diagram showing the configuration of a digital full-color copying machine according to one embodiment of the present invention.
[0009]
In FIG. 1, reference numeral 100 denotes a copying machine main body. When copying a document by the copying machine 100, first, a document 116 on a document table glass 117 is illuminated by a light source 118, and the CCD 1 converts reflected light from the document into a light amount signal. The light amount signal is processed by the image processing unit 119 as described later, and is output to the laser driver 102 as a control signal for driving the semiconductor laser.
[0010]
The laser driver 102 is a circuit for driving the semiconductor laser 103, controls the semiconductor laser 103 according to an input control signal, and switches on / off. Laser light 104 output from the semiconductor laser 103 is swung in the left and right directions by a polygon mirror 105 to scan on a photosensitive drum 106. The photosensitive drum 106 on which the latent image has been formed by the scanning of the laser beam 104 rotates in the direction indicated by the arrow in the figure, and the developing for each color is performed by the rotary developing device 112. The figure shows a state where yellow is being developed.
[0011]
On the other hand, the recording paper is wound around the transfer drum 113 and is developed by the rotary developing unit 112 in the order of Y (yellow), M (magenta), C (cyan), and BK (black) every one rotation, for a total of four times. By rotating, the four colors are transferred to the recording paper, and the color recording is completed. Then, the recording paper is separated from the transfer drum 113 and fixed by the fixing roller pair 114, and a color image print is completed.
[0012]
Next, the operation of the image processing unit 119 will be described with reference to FIG. In FIG. 2, three color light quantity signals of R (red), G (green) and B (blue) obtained from a CCD 1 through a color separation filter (not shown) are converted into digital signals by an A / D conversion circuit 2. And output to the shading circuit 3. The shading circuit 3 controls the gain of each signal so as to correspond to each CCD sensor cell so as to eliminate variations in the characteristics of the CCD sensor cells arranged in a line, and outputs the result to the LOG conversion circuit 4. I do. Then, the LOG conversion circuit 4 converts the R, G, and B luminance signals into C, M, and Y density signals and outputs the signals to the BK generation circuit 5. The BK generation circuit 5 generates a BK (black) signal using these density signals, and outputs signals of four colors of C, M, Y, and BK to the γ-LUT circuit 6. The .gamma.-LUT circuit 6 converts the signals of these four colors into gradations so that the density after printing corresponds linearly to the input density signal according to the characteristics of the printer, and outputs the signal as a serial signal.
[0013]
Then, as described later, the CPU 9 controls the gradation adjustment circuit 7 according to a control signal output from the operation unit 8 to adjust the color. The density signal whose color has been adjusted by the gradation adjustment circuit 7 is converted by the pulse width modulation circuit 10 into a signal corresponding to the emission time of the laser light according to the density signal, and is output to the laser driver 11.
[0014]
Next, the operation of the density adjustment in this embodiment will be described. FIG. 3 is a diagram showing the adjustment characteristics in the present embodiment. The horizontal axis represents the level of the input image signal, and the vertical axis represents the modulation amount. In this embodiment, the density area of the density signal is divided into three areas, that is, a low density area H, levels 0 to 80, a medium density area M 60 to 160, and a high density area S 80 to 255. The values at the time of dividing these areas are divided according to the way of feeling the density and then overlapped so that the gradations do not become discontinuous when the modulation amounts set independently as described later are combined. Things. Further, the values indicated by Δh, Δm, and Δs in the figure are the maximum values of the adjustment amounts in the respective regions, and Δh = 10, Δm = 30, and Δs = 60 . This is in accordance with the effect of the gradation change, and it is because finer adjustment of the density is desired in the low-density area, and conversely, the adjustment is not so fine in the high-density area.
[0015]
FIG. 4 is a diagram showing an operation panel for performing such density adjustment. The operation panel is provided in the operation unit 8 in FIG. 2 and, for example, a liquid crystal display panel is used. In FIG. 2, C, M, Y, and BK are marks for selecting a color to be adjusted, and H, M, and S are marks indicating the above-described density range. Then, to select a color to be adjusted, the corresponding mark of C, M, Y, or BK is pressed to select. Adjustment of each density range is performed by pressing the + and-marks. The figure shows a case where cyan is selected, the low density H is ± 0, the middle density M is +2, and the high density S is +6.
[0016]
Next, a method of adjusting the gradation characteristics will be described. The adjustment of the gradation characteristic is performed by multiplying the value of the characteristic curve shown in FIG. 3 by a ratio corresponding to the modulation amount operated on the operation panel. Table 1 shows the display value of the operation panel and the ratio by which the modulation amount shown in FIG. 3 is multiplied.
[0017]
[Table 1]

[0018]
2, a control signal corresponding to the adjustment amount adjusted by the operation panel is output from the operation unit 8 to the CPU 9 as described above, and the CPU 9 outputs a control signal to the gradation adjustment circuit 7. The tone adjusting circuit 7 is constituted by a ROM provided for each color and density range. In these ROMs, output values determined based on the adjustment characteristics shown in FIG. 3 and Table 1 are prepared as tables, which are converted and output according to the value of the input density signal. It should be noted that all the converted values exceeding 255 in each ROM are clipped to 255.
[0019]
FIG. 5 shows the gradation characteristics when the settings are made as shown in FIG. In the figure, a broken line M indicates a modulation amount in a middle density region, and a broken line S indicates a modulation amount in a high density region. The solid line indicates a modulation characteristic obtained by combining these modulation amounts.
[0020]
As described above, in the present embodiment, the adjustment characteristics are set for each density region, and the density control of the image signal is performed based on the adjustment characteristics. Therefore, the density control is performed without impairing the balance of the entire image. It becomes possible.
[0021]
Further, a configuration may be adopted in which both the tone adjustment for each density range in the present embodiment and the conventional tone adjustment (hereinafter, color balance adjustment) shown in FIG. 14 are performed. This case can also be realized by providing a ROM having a table of color balance adjustment characteristics for each color.
[0022]
FIG. 6 is a display on the operation panel when the color balance is adjusted, and shows a case where the adjustment amounts are ± 0 for C, +3 for M, −4 for Y, and ± 0 for BK. FIG. 7 is a diagram showing a configuration example of the gradation adjustment circuit 7 in the present embodiment. The gradation adjustment circuit 7 has a ROM 701 for color balance adjustment and a ROM 702 for density range adjustment. Add and output. FIG. 8 is a flowchart showing the operation of this embodiment. The operation of this embodiment will be described below with reference to FIG.
[0023]
First, a display is made on the operation panel as shown in FIG. 6, and the user determines an adjustment amount for each color (step S801). Then, after the adjustment amount is determined, in the case where further adjustment by density region is performed, the part of the adjustment by density region displayed on the upper right of the operation panel is pressed (step S802). Then, the display on the operation panel changes as shown in FIG. 4, and it is now possible to perform adjustment for each density range. Therefore, the user determines a color to be adjusted as described above (step S803), and then determines an adjustment amount for each density region (step S804). By configuring as described above, first, the overall image density is adjusted by color balance adjustment, and if further fine adjustment is desired, adjustment for each density area can be performed. It becomes easy to use for ordinary users who do not need such fine adjustment. As described above, the output of the gradation adjustment circuit 7 is configured to reflect both the density adjustment by the color balance adjustment and the adjustment for each density range.
[0024]
Next, a second embodiment of the present invention will be described. FIG. 9 shows an adjustment curve when the low density region H is adjusted to +8, the middle density region M is adjusted to -8, and the high density region S is adjusted to +8. In this case, although the adjustment curve is indicated by a solid line in FIG. 9, the gradation adjustment is discontinuous as is clear from the drawing. In particular, in the portion where the input image signal level is 70 to 85, the characteristics fall to the right, and the gradation change is inverted in this portion, resulting in a solarization effect as the characteristics of the output image signal, resulting in an unnatural image. Therefore, in this embodiment, when extreme gradation adjustment is performed on the operation panel as described above and the characteristic becomes downward-sloping, this is determined by the CPU 9 and an “abnormal image” is displayed on the operation panel. ". This allows the user to recognize that the output image is an unnatural image when such gradation adjustment is performed.
[0025]
Further, when the CPU9 determines if there adjustment characteristic is not normal, such as such right-down, eliminating the downward-sloping in the apparatus as seen by a chain line A in FIG. 9, a characteristic such that the normal adjustment characteristics If it is changed, it is possible to perform normal image adjustment in a form closest to the image that the user wants to adjust.
[0026]
Further, when the adjustment characteristics are abnormal, the apparatus displays a message indicating an abnormal image, and then allows the user to determine whether the characteristics can be automatically corrected. You may make it make it do.
[0027]
The above operation including the color balance adjustment will be described with reference to the flowchart of FIG. First, the color balance is adjusted by the display on the operation panel shown in FIG. 6 (step S101). Next, when performing adjustment for each density region, the display portion is pressed to change to a panel for performing adjustment for each density region (step S102). After the color to be adjusted is determined (step S103), the adjustment amount is determined for each density region (step S104). Next, it is determined whether or not the adjustment characteristics determined in step S104 are normal (step S105). If the adjustment characteristics are normal, conversion is performed using the characteristics as they are and output.
[0028]
If it is determined in step S105 that the adjustment characteristics are not normal, an error image is displayed on the operation panel (step S106). Then, whether or not the adjustment characteristics are automatically changed on the device side is displayed on the operation panel. If the user can change the adjustment characteristics, the CPU 9 changes the readout address of the ROM 702 for each density region as described above. The characteristics are corrected and output so as to obtain normal adjustment characteristics (step S107). If the user refuses to change the characteristic on the device side in step S107, a message indicating that the change in the adjustment amount is supported is displayed on the operation panel (step S108), and the process returns to step S104.
[0029]
In the above-described embodiment, a message is displayed when the adjustment characteristic is abnormal, but any message may be used as long as the user can recognize it. For example, the buzzer chime Notification by sound such as LED, and notification by light such as LED. Further, when the adjustment characteristics are abnormal, a configuration may be adopted in which after the display is performed, the characteristics are corrected by the apparatus without permission.
[0030]
Further, in the above-described embodiment, the case where the adjustment characteristic is abnormal is taken as an example in the case where the curve goes down to the right. However, other than this, for example, when the density becomes flat after a sharp rise (or fall) in density, etc. However, similar image quality abnormality may be recognized, and in such a case, it is possible to notify the user of the abnormal image by similarly issuing a warning.
[0031]
Next, a third embodiment of the present invention will be described. In the above-described first and second embodiments, the density adjustment is performed based on the adjustment characteristics shown in FIG. 3. In this case, the density is increased and decreased as shown by the broken line in FIG. It is conceivable that the degree of modulation in the vertical direction (the angle of the modulation characteristic with respect to the straight line) differs from the unadjusted state shown by the straight line in FIG. To avoid this, as shown by the solid line in FIG. 11, when increasing or decreasing the density in each density range, it is desirable to set the modulation characteristic so that the characteristic changes symmetrically with respect to a straight line. .
[0032]
Therefore, in the present embodiment, as shown in FIG. 12, an adjustment characteristic different from the adjustment characteristic shown in FIG. 3 is newly set as the modulation characteristic, and the modulation characteristic is perpendicular to the straight line in FIG. The configuration is such that the adjustment characteristics are symmetric in the direction.
[0033]
By setting the adjustment characteristics in this manner, the change in density becomes symmetric between the case of increasing the density and the case of decreasing the density, and the image quality after the density adjustment does not deteriorate.
[0034]
With the same idea, as shown in FIG. 13, the final adjustment characteristic may be set by determining the modulation amount vertically for each density region from the unadjusted state. However, in this case, it is necessary to calculate a new adjustment amount for the straight line shown in FIG. 12 in order to obtain a curve of the adjustment characteristic, and then add the straight line to obtain the final adjustment characteristic.
[0035]
As described above, even when the density adjustment is performed based on the adjustment characteristics shown in FIG. 13, there is no concern about deterioration of the image quality after the density adjustment as in the above-described embodiment.
[0036]
In the above-described embodiment, the ROM is used in the gradation adjusting means. However, the present invention is not limited to this, as long as it has a so-called look-up table (LUT) function of outputting an output corresponding to an input image signal. Alternatively, only the adjustment characteristics as shown in FIG. 3 may be stored in the ROM, prepared for each color, and the ratio shown in Table 1 may be inputted from an external control means and finally added. .
[0037]
【The invention's effect】
According to the present invention, since the adjustment degree can be set independently for a plurality of density regions, it is possible to instruct a desired density adjustment without impairing the overall image balance.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a color copying machine according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating a configuration of an image processing unit in the color copying machine of FIG. 1;
FIG. 3 is a diagram illustrating an example of an adjustment characteristic in the embodiment of the present invention.
FIG. 4 is a diagram showing a display on an operation panel according to the embodiment of the present invention.
FIG. 5 is a diagram showing adjustment characteristics obtained by integrating adjustment characteristics of each density region in the gradation adjustment circuit.
FIG. 6 is a diagram showing a display on an operation panel according to the present invention.
FIG. 7 is a diagram illustrating a configuration of a gradation adjustment circuit according to an embodiment of the present invention.
FIG. 8 is a flowchart for explaining an embodiment of the present invention.
FIG. 9 is a diagram showing another example of the adjustment characteristics set on the operation panel.
FIG. 10 is a flowchart for explaining an embodiment of the present invention.
FIG. 11 is a diagram showing another example of the adjustment characteristics in the embodiment of the present invention.
12 is a diagram showing an example of the adjustment characteristics shown in FIG. 11 for each density region.
FIG. 13 is a diagram showing still another example of the adjustment characteristics in the embodiment of the present invention.
FIG. 14 is a diagram for explaining a conventional technique.
[Explanation of symbols]
7 gradation adjustment circuit 8 operation unit 9 CPU

Claims (2)

An operation unit for inputting a user's instruction regarding the degree of adjustment independently for a plurality of density ranges,
Setting means for setting an adjustment characteristic from an adjustment degree according to the density range,
An image processing apparatus having a density adjustment unit that performs density adjustment based on the set adjustment characteristics,
The plurality of density ranges overlap with adjacent density ranges,
The setting means, the density range from the maximum adjustment amount in a low-density adjustment of the width at a high density area is wide the maximum compared to the range determined for each degree of adjustment and the concentration range corresponding to the concentration zone An image processing apparatus comprising: obtaining a modulation amount for each of the modulation amounts; and, when there is a reversal of a gradation change in a combination of the modulation amounts, correcting the reversal of the gradation change and setting the adjustment characteristic. Enter the user's instruction regarding the degree of adjustment independently for multiple density ranges,
From the adjustment degree according to the density range, an adjustment characteristic is obtained,
An image processing method for performing density adjustment based on the set adjustment characteristics,
The plurality of density ranges overlap with adjacent density ranges,
The adjustment characteristic, the density range from the adjustment degree and the adjustment amount of the a maximum adjustment amount determined for each concentration range width in the high density region than in the low concentration range is wide the maximum corresponding to the concentration zone An image processing method comprising: obtaining a modulation amount for each of the modulation amounts; and, when there is a reversal of a gradation change in a composite of the modulation amounts, correcting the reversal of the gradation change .

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