JP3682382B2 - Image processing system and recording medium - Google Patents

Description

ａ１からａ８は「０」または「１」
で表される。最上位のビットプレーン６０１−１はａ１の値を示し、ビットプレーン６０１−２はａ２の値を示し、以下同様に、各ビットプレーンがａ３、ａ４……の値を示す。
【００１７】
８枚のビットプレーン６０１−１、６０１−２、…、６０１−８の領域Ａの画素のビット値は下位方向に１ビットずつシフトされ、画像４０２が得られる。このとき画像４０１における領域Ａの最下位ビットの内容は破棄されるが、最下位ビットの変化は画質に対する影響が小さいため問題はない。
【００１８】
得られた画像４０２の最上位ビットプレーン６１１−１の領域Ａの画素のビット値は、可視電子透かしの２値画像２０１と置き換えられ、画像４１１が得られる。即ち、輝度プレーンの画像４１１には可視電子透かしが挿入されたことになる。
【００１９】
図５は、可視電子透かし挿入処理において、領域Ａ及び領域Ｂ内の一つの画素のビット値を示す図である。図５に示すビット８１−１は画像４０１のビットプレーン６０１−１の領域Ａのある画素の値であり、ビット値は「１」である。同様にビット８１−２、８１−３、…、８１−８は画像４０１のビットプレーン６０１−２、６０１−３、…、６０１−８の同じ画素の値であり、ビット値は「０」、「１」、…、「０」となる。
【００２０】
図５に示すように、画像４０１においてビット８１−１からビット８１−７の値が下位方向へシフトされる。即ち、画像４０２のビット８２−２から８２−８にビット８１−１からビット８１−７の値が入り、ビット８１−８の内容は破棄される。このとき図５ではビット８２−１に「０」が入れられるが、これは「１」でもよい。
【００２１】
次に、ビット８２−１の値を、可視電子透かしパターン即ち画像２０１の相当画素の値である「０」と置き換える。こうして可視電子透かしが挿入された画像４１１が得られる。
【００２２】
一方、図５に示す領域Ｂの画素のビット値は画像４０１、画像４０２、画像４１１において変わらない。
但し、本実施の形態では領域Ａと領域Ｂとを判別するための情報を画像４１１に持たしていないため、図５に示す最下位のビット９１に領域を判別するための情報を与えることもできる。例えば、領域Ａのビットシフト処理後、領域Ａの画素のビット８２−８を値を「１」、領域Ｂの画素のビット９１の値を「０」とすることで、領域の判別が可能となる。
【００２３】
ステップ２４
こうして作成した画像４１１と画像５０１とから色空間の変換を行い、原画像１０１と同様の色空間で表現された可視電子透かし入りの画像１１１が得られる。例えば、ＹＰｂＰｒ色空間からＲＧＢ色空間への変換は次式によって行われる
。
【００２４】
Ｒ＝１．５７６Ｐｒ＋Ｙ
Ｂ＝１．８２６Ｐｂ＋Ｙ …（２）
Ｇ＝（Ｙ−０．０８７Ｂ−０．２１２Ｒ）／０．７０１
【００２５】
こうして作成された透かし入りの画像１１１は、原画像１０１と比較すると、領域Ａの輝度情報には変化が発生するが、色空間変換が可逆であれば、輝度以外の成分には変化が発生しないため、領域Ａは原画像１０１の色相を損なわない。また、色空間変換時の誤差が肉眼では判別できない程度であれば、色相への影響も無視できる。
【００２６】
また、ビットシフト処理を用いて輝度プレーンに透かしを挿入することで、ビットプレーンの大小関係が保持され、電子透かしが半透明的に挿入され、画質への影響が少ない。
【００２７】
次に、画像１１１から可視電子透かしを除去する作業手順について説明する。図６は可視電子透かしの除去作業のフローチャートであり、図７は除去作業の説明図である。
【００２８】
透かし入りの画像１１１の色空間変換を行う（ステップ６１）。画像１１１はＲＧＢ色空間で表現されているので、（１）式によってＹＰｂＰｒ色空間で表現される画像３１１に変換される。画像３１１は輝度プレーンの画像４１１とその他の情報の画像５１１に分けられる。
【００２９】
次に、画像３１１の輝度プレーン画像４１１の領域Ａに対してビットシフト処理を行い（ステップ６２）、画像４２１が得られる。ここで、領域Ａと領域Ｂの判別に必要な情報は入力により与えられるが、前述のように図５に示す最下位ビット９１の値に情報を入れておき、それを参照することも可能である。
【００３０】
画像４２１と画像５１１とから色空間の逆変換を行い（ステップ６３）、可視電子透かしの除去された画像１２１が得られる。例えば、元のＲＧＢ色空間に変換する場合は（２）式を用いる。
【００３１】
次に、図６の各ステップについて更に詳しく説明する。
ステップ６２
図８は輝度プレーン画像４１１のビットシフト処理の説明図である。画像４１１は８枚のビットプレーン６１１−１、６１１−２、…、６１１−８に分割される。最上位ビットプレーン６１１−１の領域Ａには、可視電子透かしの画像２０１が挿入されている。
【００３２】
８枚のビットプレーン６１１−１、６１１−２、…、６１１−８の領域Ａの画素のビット値は上位方向に１ビットずつシフトされ、画像４２１が得られる。即ち、最上位プレーン６２１−１の領域Ａに挿入されていた画像２０１は上書きされ、可視電子透かしが除去されたことになる。
【００３３】
図９は、可視電子透かし除去処理において、領域Ａ及び領域Ｂ内の一つの画素のビット値を示す図である。図９に示すビット８５−１には可視電子透かしの画像２０１のビット値「０」が入っているが、ビット８５−２からビット８５−８の値を上位方向にシフトすることにより、ビット８５−２の値「１」が入り、ビット８５−１の値は破棄される。
一方、領域Ｂの画素のビット値には変化がない。
【００３４】
このようにビットシフト処理を行うことで、ビット８７−１、…、８７−７の値がそのまま復元されるため、可視電子透かしを除去した画像１２１と原画像１０１と生じる誤差は非常に少なく、無視できる。また、透かしも輝度プレーンに挿入除去されることから、色相への影響が少ない。
【００３５】
このように、本実施の形態によれば、可視電子透かしを挿入することで画像の権利情報を明示することができ、かつ可視電子透かしを任意に除去できることから画像の意匠性を保つことができる。また、透かし挿入時も、透かしが輝度プレーンに挿入されるので画像の色相を損なうことが少ない。
【００３６】
なお、本実施の形態では、原画像１０１がＲＧＢ画像であったが、ＨＳＶ、ＹＩＱなどといった他の色空間表現の画像であっても色空間ＹＰｂＰｒに変換すれば同様に可視電子透かしを挿入、除去できる。
【００３７】
また、本実施の形態では、輝度プレーンの最上位ビットプレーンの領域Ａを電子透かしの画像２０１に置き換えて透かしを挿入したが、可視電子透かしはどのビットプレーンにも挿入可能である。この場合、可視電子透かしを挿入するビットプレーンと、それより下位のビットプレーンのみをビットシフトの対象とすればよい。可視電子透かしを挿入するビットプレーンが下位になるほど、可視電子透かしは目立たなくなるため、要求される可視電子透かしの見え具合に応じてビットプレーンを選択することが可能である。
【００３８】
また、本実施の形態では、ビットシフト処理によって原画像の情報を待避させたが、例えば最上位ビットプレーンの領域Ａを最下位ビットプレーンに退避させ、最上位プレーンの領域Ａに２値画像を挿入するようにしてもよい。この場合、透かしを除去するには、最下位ビットプレーンに退避させていた値を最上位ビットプレーンに書き込むことにより行う。
【００３９】
また、本実施の形態で述べたような処理をコンピュータに行わせるためのプログラムはＣＤ−ＲＯＭ等の記録媒体に記録される。例えば、ネットワークを介して可視電子透かし入りの画像を与え、正式なクライアントにはこのような記録媒体を配布し、透かしが除去できるようにするなどといった利用方法もある。
【００４０】
【発明の効果】
以上、詳細に説明したように本発明によれば、画像の意匠性を損なうことなく、その権利情報を明示することができる。
【図面の簡単な説明】
【図１】 本発明の１実施の形態に係る画像処理システム１を示す図
【図２】 可視電子透かし挿入処理を示すフローチャート
【図３】 挿入処理を示す模式図
【図４】 輝度プレーンのビットシフト処理を示す模式図
【図５】 挿入時の領域Ａ及び領域Ｂの画素値を示す図
【図６】 可視電子透かし除去処理を示すフローチャート
【図７】 除去処理を示すを示す図
【図８】 輝度プレーンのビットシフト処理を示す模式図
【図９】 除去時の領域Ａ及び領域Ｂの画素値を示す図
【符号の説明】
１………画像処理システム
３………コンピュータ
５………外部記憶装置
７………マウス
１０１………原画像
４０１、４１１………輝度プレーン画像
１１１………可視電子透かし入り画像[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image processing system using a visible digital watermark and a recording medium on which a program is recorded.
[0002]
[Prior art]
In recent years, when a digital image is transmitted on the Internet or the like, rights information or the like is sometimes inserted into the image. For example, in the displayed image, information indicating who the copyright owner of the image belongs is inserted. There are visible watermarks that are visible and invisible watermarks that are invisible, as digital watermark techniques that insert rights information and the like into an image. Visible watermarks can specify rights information.
[0003]
[Problems to be solved by the invention]
However, when a visible digital watermark is inserted into an image, there is a problem that the hue of the image of the portion where the watermark is inserted is impaired, that is, the design of the image is impaired.
[0004]
The present invention has been made in view of such problems, and the object of the present invention is to insert a visible digital watermark to clearly indicate right information and the like, and to remove the visible digital watermark when necessary to improve the design of the image. An object of the present invention is to provide an image processing system that can be maintained.
[0005]
[Means for Solving the Problems]
The first invention for achieving the above-described object is divided into means for dividing the first image into an image of a luminance plane and an image of color information other than luminance, and means for dividing the luminance plane into bit planes. Of the bit planes, the bit planes on the lower side of the bit plane over which the binary image is overwritten are bit-shifted beforehand to the lower side, and the value of each bit plane in the area over which the binary increase is overwritten. Means for discarding the value of the lower bit plane, overwriting the binary image on one of the divided bit planes, and generating the second image together with the other bit planes; An image processing system comprising: means for generating a third image from an image of color information.
Further, the image processing system generates a third image generated by a luminance plane image and an image of color information other than luminance, a removing unit for removing a binary image from the luminance plane image, and 2 It is preferable to include a luminance plane image from which the value image is removed, and a unit that performs color space conversion on an image of color information other than luminance to generate a fourth image. The removing unit divides the luminance plane into bit planes, bit-shifts the value of each bit plane in the area where the binary image is inserted, and writes 0 or 1 to the lowest bit plane.
Further, the second invention is a means for dividing the first image into an image of a luminance plane and an image of color information other than luminance, a means for dividing the luminance plane into bit planes, and among the divided bit planes, The value of the bit plane of the area where the binary image is overwritten is overwritten in advance on another bit plane and saved, and the binary image is overwritten on one of the divided bit planes, and the second bit is stored together with the other bit plane. An image processing system comprising: means for generating the second image; and means for generating a third image from the second image and an image of color information other than the luminance plane.
Further, the image processing system generates a third image generated by the luminance plane and a color information image other than the luminance, a removing unit for removing the binary image from the luminance plane image, and 2 It is preferable to include a luminance plane image from which the value image is removed, and a unit that performs color space conversion on an image of color information other than luminance to generate a fourth image. The removing unit divides the luminance plane into bit planes, and replaces the bit plane values of the divided bit planes where the binary image has been inserted with values previously saved in other bit planes. .
[0006]
The third invention is a recording medium on which a program for functioning as the image processing system of the first invention is recorded, and the fourth invention is recorded with a program for functioning as the image processing system of the second invention. Recording medium.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an image processing system 1 according to the present embodiment.
[0008]
An auxiliary storage device 5 and a mouse 7 are connected to the computer 3. In the computer 3, visible digital watermark insertion and removal processing is performed on the image read from the auxiliary storage device 5. The mouse 7 is used to input operation instructions, positions, numerical values, and the like.
[0009]
Next, the visible digital watermark insertion process by the image processing system 1 will be described. FIG. 2 is a flowchart of the visible digital watermark insertion process, and FIG. 3 is a schematic diagram showing an outline of the insertion process.
[0010]
As shown in FIG. 3, a visible digital watermark image 201 is inserted into the original image 101 to obtain an image 111, and a region where the image 201 is inserted is a region A, and a region where the image 201 is not inserted is a region B.
[0011]
Color space conversion of the original image 101 is performed (step 21), and the image 301 is converted into a color space composed of luminance information and other information. In the image 301, an image composed of luminance planes is an image 401, and an image indicating other information is an image 501. Here, when the original image 101 is an image in a color space that originally includes luminance information, the processing of step 21 is not necessary, and the luminance plane of the original image 101 may be the image 401.
[0012]
Next, a bit shift process is performed on the area A of the image 401 composed of the luminance plane of the image 301 (step 22) to obtain an image 402. A region A of a specific bit plane such as the most significant bit plane in the image 402 is replaced with a binary image 201 of a visible digital watermark, and a watermark is inserted (step 23).
[0013]
The color space is inversely transformed from the image 411 including the visible digital watermark thus created and the plane image 501 other than the luminance (step 24), thereby obtaining the image 111 into which the visible digital watermark is inserted.
[0014]
Hereinafter, each step of FIG. 2 will be described in more detail.
Step 21
When the original image 101 is an image expressed in the RGB color space, each pixel value is converted by the following expression, and converted into a color space YPbPr, YIQ, or the like composed of luminance information and other information. Here, the case of converting to the color space YPbPr will be described. Of the color space YPbPr, Y is a luminance signal, and Pb and Pr are color difference signals.
[0015]
Y = 0.121R + 0.701G + 0.087B
Pb = −0.116R−0.384G + 0.500B (1)
Pr = 0.500R-0.445G-0.055B
Thus, the original image 101 is expressed in the color space YPbPr, the Y plane of which is the luminance plane image 401, and the Pb plane and the Pr plane are the images 501.
[0016]
Step 22 and Step 23
FIG. 4 is an explanatory diagram of the bit shift process of the luminance plane. As shown in FIG. 4, for example, if the image 401 is an image having 256 gradations, the image 401 is divided into eight bit planes 601-1, 601-2,. Bit plane 601-1 is the most significant bit plane, and bit plane 601-8 is the least significant bit plane.
If the value of a pixel here is X,

a1 to a8 are “0” or “1”
It is represented by The most significant bit plane 601-1 indicates the value of a1, the bit plane 601-2 indicates the value of a2, and similarly, each bit plane indicates the values of a3, a4,.
[0017]
The bit values of the pixels in the area A of the eight bit planes 601-1, 601-2, ..., 601-8 are shifted one bit at a time in the lower direction, and an image 402 is obtained. At this time, the content of the least significant bit of the area A in the image 401 is discarded, but there is no problem because the change of the least significant bit has little influence on the image quality.
[0018]
The bit value of the pixel in the area A of the most significant bit plane 611-1 of the obtained image 402 is replaced with the binary image 201 of the visible digital watermark, and the image 411 is obtained. In other words, the visible digital watermark is inserted into the image 411 of the luminance plane.
[0019]
FIG. 5 is a diagram illustrating a bit value of one pixel in the region A and the region B in the visible digital watermark insertion process. A bit 81-1 illustrated in FIG. 5 is a value of a pixel in the area A of the bit plane 601-1 of the image 401, and the bit value is “1”. Similarly, the bits 81-2, 81-3,..., 81-8 are the same pixel values of the bit planes 601-2, 601-3,. “1”,..., “0”.
[0020]
As shown in FIG. 5, in the image 401, the values of bits 81-1 to 81-7 are shifted downward. That is, the values of bits 81-1 to 81-7 are entered in bits 82-2 to 82-8 of the image 402, and the contents of bit 81-8 are discarded. At this time, “0” is put in bit 82-1 in FIG. 5, but it may be “1”.
[0021]
Next, the value of bit 82-1 is replaced with “0” which is the value of the corresponding pixel of the visible digital watermark pattern, that is, the image 201. In this way, an image 411 with a visible digital watermark inserted is obtained.
[0022]
On the other hand, the bit values of the pixels in the region B shown in FIG. 5 do not change in the image 401, the image 402, and the image 411.
However, in the present embodiment, since the image 411 does not have information for discriminating between the region A and the region B, information for discriminating the region may be given to the least significant bit 91 shown in FIG. it can. For example, after the bit shift process of the area A, the value of the bit 82-8 of the pixel of the area A is set to “1”, and the value of the bit 91 of the pixel of the area B is set to “0”. Become.
[0023]
Step 24
The color space is converted from the image 411 and the image 501 thus created, and an image 111 with a visible digital watermark expressed in the same color space as the original image 101 is obtained. For example, conversion from the YPbPr color space to the RGB color space is performed by the following equation.
[0024]
R = 1.576Pr + Y
B = 1.826Pb + Y (2)
G = (Y−0.087B−0.212R) /0.701
[0025]
Compared with the original image 101, the watermarked image 111 created in this way changes in the luminance information of the area A, but if the color space conversion is reversible, no change occurs in components other than the luminance. Therefore, the area A does not impair the hue of the original image 101. In addition, if the error at the time of color space conversion is indistinguishable with the naked eye, the influence on the hue can be ignored.
[0026]
In addition, by inserting a watermark into the luminance plane using the bit shift process, the size relationship between the bit planes is maintained, the digital watermark is inserted translucently, and the influence on the image quality is small.
[0027]
Next, an operation procedure for removing the visible digital watermark from the image 111 will be described. FIG. 6 is a flowchart of the removal operation of the visible digital watermark, and FIG. 7 is an explanatory diagram of the removal operation.
[0028]
Color space conversion of the watermarked image 111 is performed (step 61). Since the image 111 is expressed in the RGB color space, the image 111 is converted into an image 311 expressed in the YPbPr color space by the equation (1). The image 311 is divided into a luminance plane image 411 and other information image 511.
[0029]
Next, bit shift processing is performed on the area A of the luminance plane image 411 of the image 311 (step 62), and an image 421 is obtained. Here, the information necessary for discrimination between the area A and the area B is given by input. However, as described above, it is also possible to refer to the information by putting the information in the value of the least significant bit 91 shown in FIG. is there.
[0030]
The color space is inversely transformed from the image 421 and the image 511 (step 63), and the image 121 from which the visible digital watermark is removed is obtained. For example, when converting to the original RGB color space, equation (2) is used.
[0031]
Next, each step of FIG. 6 will be described in more detail.
Step 62
FIG. 8 is an explanatory diagram of the bit shift process for the luminance plane image 411. The image 411 is divided into eight bit planes 611-1, 611-2, ..., 611-8. A visible digital watermark image 201 is inserted into the area A of the most significant bit plane 611-1.
[0032]
The bit values of the pixels in the area A of the eight bit planes 611-1, 611-2,..., 611-8 are shifted one bit at a time in the upper direction, and an image 421 is obtained. That is, the image 201 inserted in the area A of the uppermost plane 621-1 is overwritten, and the visible digital watermark is removed.
[0033]
FIG. 9 is a diagram illustrating a bit value of one pixel in the region A and the region B in the visible digital watermark removal process. Bit 85-1 shown in FIG. 9 contains the bit value “0” of the image 201 of the visible digital watermark. By shifting the value of bits 85-2 to 85-8 in the upper direction, bit 85-1 is displayed. -2 is entered, and the value of bit 85-1 is discarded.
On the other hand, the bit value of the pixel in the region B does not change.
[0034]
By performing the bit shift processing in this way, the values of the bits 87-1,..., 87-7 are restored as they are, so that there are very few errors between the image 121 from which the visible digital watermark is removed and the original image 101. Can be ignored. Further, since the watermark is also inserted and removed from the luminance plane, the influence on the hue is small.
[0035]
As described above, according to the present embodiment, it is possible to clarify the right information of an image by inserting a visible digital watermark, and it is possible to arbitrarily remove the visible digital watermark, so that the design of the image can be maintained. . In addition, even when a watermark is inserted, since the watermark is inserted into the luminance plane, the hue of the image is hardly impaired.
[0036]
In the present embodiment, the original image 101 is an RGB image, but even if it is an image of another color space expression such as HSV or YIQ, a visible digital watermark is similarly inserted if converted to the color space YPbPr. Can be removed.
[0037]
In this embodiment, the watermark A is inserted by replacing the region A of the most significant bit plane of the luminance plane with the digital watermark image 201, but the visible digital watermark can be inserted into any bit plane. In this case, only the bit plane into which the visible digital watermark is inserted and the bit plane lower than the bit plane may be set as the bit shift targets. As the bit plane into which the visible watermark is inserted becomes lower, the visible watermark becomes less conspicuous. Therefore, it is possible to select the bit plane according to the required visibility of the visible watermark.
[0038]
Further, in the present embodiment, the information of the original image is saved by the bit shift process. However, for example, the area A of the most significant bit plane is saved to the least significant bit plane, and the binary image is saved in the area A of the most significant plane. You may make it insert. In this case, the watermark is removed by writing the value saved in the least significant bit plane to the most significant bit plane.
[0039]
A program for causing a computer to perform the processing described in this embodiment is recorded on a recording medium such as a CD-ROM. For example, there is a utilization method in which an image with a visible digital watermark is given via a network, and such a recording medium is distributed to an official client so that the watermark can be removed.
[0040]
【The invention's effect】
As described above in detail, according to the present invention, the right information can be specified without impairing the design of the image.
[Brief description of the drawings]
FIG. 1 is a diagram showing an image processing system 1 according to an embodiment of the present invention. FIG. 2 is a flowchart showing visible digital watermark insertion processing. FIG. 3 is a schematic diagram showing insertion processing. FIG. 5 is a schematic diagram showing shift processing. FIG. 5 is a diagram showing pixel values in region A and region B at the time of insertion. FIG. 6 is a flowchart showing visible digital watermark removal processing. ] Schematic diagram showing bit shift processing of luminance plane [FIG. 9] Diagram showing pixel values in region A and region B upon removal [Explanation of Symbols]
DESCRIPTION OF SYMBOLS 1 ......... Image processing system 3 ......... Computer 5 ......... External storage device 7 ...... Mouse 101 ......... Original image 401, 411 ...... Luminance plain image 111 ...... Image with visible digital watermark

Claims (6)

Means for dividing the first image into an image of a luminance plane and an image of color information other than luminance;
Means for dividing the luminance plane into bit planes;
Of the divided bit planes, the bit plane value lower than the bit plane on which the binary image is overwritten is bit-shifted in advance to the lower side of the value of each bit plane in the area where the binary image is overwritten, Means for discarding the value of the least significant bit plane, overwriting the binary image on any of the divided bit planes, and generating a second image along with the other bit planes;
Means for generating a third image from the second image and an image of color information other than the luminance plane;
An image processing system comprising: Means for dividing the generated third image into an image of a luminance plane and an image of color information other than luminance by the image processing system according to claim 1;
Removing means for removing the binary image from the image of the luminance plane;
Means for generating a fourth image by performing color space conversion on an image of a luminance plane from which a binary image has been removed and an image of color information other than the luminance;
Comprising
The removing means divides the luminance plane into bit planes, bit-shifts the value of each bit plane in the area where the binary image is inserted, and writes 0 or 1 to the lowest bit plane. The image processing system according to claim 1. Means for dividing the first image into an image of a luminance plane and an image of color information other than luminance;
Means for dividing the luminance plane into bit planes;
Of the divided bit planes, the value of the bit plane in the area where the binary image is overwritten is saved in advance by overwriting another bit plane, and the binary image is overwritten on any of the divided bit planes. Means for generating a second image along with other bit planes;
Means for generating a third image from the second image and an image of color information other than the luminance plane;
An image processing system comprising: Means for dividing the generated third image into an image of a luminance plane and an image of color information other than luminance by the image processing system according to claim 3;
  Removing means for removing the binary image from the image of the luminance plane;
  Means for generating a fourth image by performing color space conversion on an image of a luminance plane from which a binary image has been removed and an image of color information other than the luminance;
Comprising
  The removing means divides the luminance plane into bit planes, and the value of the bit plane in the divided bit plane in which the binary image is inserted is previously saved in another bit plane. The image processing system according to claim 3, wherein A recording medium on which a program for causing a computer to function as the image processing system according to claim 1 is recorded. A recording medium on which a program for causing a computer to function as the image processing system according to claim 3 is recorded.

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