JP3208063B2 - Image information processing method and processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for processing an image photographed by a television camera or the like, and more particularly to an apparatus for processing an input image by LU.
The present invention relates to a processing method of performing T conversion and displaying.

[0002]

2. Description of the Related Art Electronic image data photographed by various television cameras including infrared rays, X-rays, etc. is converted into LUTs for each pixel.
(Lookup table) A method is known in which the image quality is adjusted by conversion and displayed on a display or a printer.

For example, an image processing apparatus for displaying satellite images on a display or the like is described in an image analysis handbook (edited by Mikio Takagi and Yoshihisa Shimoda; PP. 478-481). Here, as shown in FIG. 8, a satellite image of 1024 pixels by 1024 pixels in length and width stored in the storage device 200 is input to the image processing device 100, and a predetermined brightness level value of each pixel of the image is set. LUT conversion is performed with reference to the LUT and output to the output display device 4. At this time, a histogram of the entire image is obtained, an LUT is created from the histogram, and LUT conversion is performed to improve image quality. This histogram conversion method is a method of performing conversion while paying attention to the frequency of the luminance level value in an image.

[0004] Even when a similar technique is used to display a color image (multi-band image) for improving the image quality, a multi-band histogram is created for the entire image at once, an LUT is created, and LUT conversion is performed. I do.

[0005]

In the above-described conventional histogram conversion method, since an LUT is created by collectively obtaining a histogram for the entire image, even when a large amount of data such as a satellite image or a color image is displayed, the image display is performed. Spend a lot of time on

For example, a satellite image is represented by an image of 6000 pixels × 6000 pixels in the vertical and horizontal directions, and as shown in FIG.
In general, there are cases where objects having strong reflection characteristics such as sea areas and objects having weak reflection characteristics such as agricultural lands and parks are mixed, and the luminance level values of images are not uniformly distributed. Therefore, L
The image quality needs to be improved by UT conversion, and the display processing requires a great deal of time.

Further, an LUT is obtained from the histogram of the entire image.
Is created, the LUT may not always match the display area that is a part of the entire image, and the display image may be blurred. In such a case, the user changes the LUT of the display image and repeats the operation of redisplaying to obtain a display image that is easy to see without blur.

Further, in recent satellite images, the amount of information keeps increasing, and luminance levels of 11 to 12 bits are also planned. For this reason, in a display device in which the luminance level value of the output display is insufficient with respect to the luminance level value of the input image, time is also required for preprocessing such as cutting off the number of upper and lower bits.

An object of the present invention is to provide an image display method which overcomes the problems of the prior art, simplifies the process of creating an LUT, and can display an image with improved image quality at high speed.

[0010]

An object of the present invention is to read out an input image of a designated target area from a whole image by using a luminance value for each pixel, and look up a look-up table (hereinafter referred to as an LU).
In the processing method of the image information in which the image quality is adjusted by the LUT conversion based on the set value of T) and the output is performed, the moving amount of the current target area with respect to the previous target area is smaller than a predetermined value. Performs LUT conversion of the luminance value of the current input image using the set value of the LUT used last time, and performs a predetermined calculation such as calculation of a histogram based on the luminance value of the current input image if the luminance value is larger than the specified value. This is achieved by updating the LUT and then performing LUT conversion of the luminance value of the current input image.

If the luminance value scale of the input image is different from the luminance value scale of the output image output after the LUT conversion, the luminance value of the input image is calculated when calculating the set value of the LUT based on the histogram. Is linearly converted into a brightness value scale of the output image.

Further, when the whole image is a multi-band image such as a color image, reading of the input image and calculation of the histogram are performed for each band.

According to the configuration of the present invention described above, when displaying an input image of a target area, a histogram is calculated at the same time, and an LUT optimum for the target area is calculated from the histogram.
Can be created. This LUT is omitted when the designated position is moved by scrolling and the movement amount is smaller than an arbitrarily set specified value, and the previous LUT value is used. This utilizes the fact that there is generally no significant change in the brightness level value in the area near the image.

The present invention can be applied to a multi-band image, such as creating a color LUT and outputting and displaying a color image.

According to the present invention, when the luminance value scale of the output display device is different from the luminance value scale of the input image (for example, the former has 8 bits (0 to 255), the latter has 6 bits (0 to 6).
3)) Since the linear conversion is performed so as to adapt to the luminance value scale of the output image when the histogram is created, the operation is simplified. Further, when an input image having a high luminance level such as a satellite image is output to a normal display device, it is possible to secure a certain image quality according to the input data.

The image information processing apparatus to which the method of the present invention is applied can be easily applied to a commercially available display device without using a dedicated device.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings, taking a satellite image display process as an example. Note that the same reference numerals are given to the same elements throughout the drawings.

[Embodiment 1] FIG. 1 shows a configuration diagram of an image information processing apparatus according to the present embodiment. First, an outline of the configuration and operation of the present apparatus will be described.

The storage device 3 stores a satellite image 3 of M × N pixels.
All data of 0 are stored. An arbitrary display area image 30 a of m × n pixels is read by scrolling the image input unit 10 of the image processing device 1 in accordance with a user instruction from the display area instruction device 4. The target display area to be read has an m × n pixel size displayed on the output display device 5. The display area image 30a is written in the input address table 22 of the LUT setting unit 20.

The image input unit 10 comprises a displacement amount calculating means 13, an output position calculating means 12, and a target area image input means 11. When the user designates an arbitrary target display area, the shift amount calculating means 13 calculates the shift amount from the previous display area and passes it to the control means 21 of the LUT setting section 20.

The control means 21 inputs the contents of the input address table 22 to the LUT conversion means 27 through the switching means 23 when the displacement amount is equal to or less than the predetermined value. The LUT conversion means 27 performs LUT conversion of each luminance value of the input address table 22 based on the previously used table value of the LUT 26, updates the luminance value of the converted luminance value table 28, and outputs the updated luminance value to the output display device 4.

On the other hand, if the amount of displacement is larger than the predetermined value, the switching means 23 is controlled, and the input target display area image 20a is once passed to the histogram creating means 24 to calculate a histogram, and based on the histogram. LUT
The creation means 25 creates an LUT for the target display area, and
Update T26. After that, the switching unit 23 is controlled to input the contents of the input address table 22 to the LUT conversion device 27. The LUT conversion device 27 uses the updated LU
Based on the table value of T26n, the target display image 20a
Are subjected to LUT conversion, the converted luminance value table 28 is updated and output to the output display device 5. As the output display device 5, a display 51, a printer 52, a film 53, and the like are provided.

FIG. 3 shows a flowchart of the image processing method according to the present embodiment. First, the maximum value (M or N in the above example) at the time of scrolling is set as the initial value V0 of the displacement amount (S101). When the display area instruction is input (S102), the output position of the target display area is calculated (S104) while calculating the shift amount from the previous output position held (S103). M × n
An image is input (S105).

Next, it is determined whether or not the displacement calculated in S103 exceeds a specified value (S106). If it exceeds, a histogram of the display area image is calculated (S107).
An LUT is created and updated according to the histogram (S
108). Based on this LUT, target m × n pixels are represented by L
UT conversion is performed (S109), and the luminance value of the target display area image is output to the display device (S110). If the amount of displacement is equal to or less than the specified value in the determination of S106, LUT conversion is immediately performed. The above method is repeated until the scroll is completed (S111).

Here, the process of creating a histogram from input image data, creating an LUT, and performing LUT conversion to the luminance value of the converted luminance level table 28 will be described in detail.

FIG. 4 is an explanatory diagram showing from the input image to the LUT conversion. The target display area image 30a of the designated m × n pixel size is temporarily stored in the input address table 22.
Is stored in In the first time, a histogram is created based on the displacement initial value V0, and L is created based on the histogram.
LUT conversion processing is performed by the UT.

Next, in accordance with the designation change of the target display area by scrolling, the coordinate position is calculated from the displacement from the previous display area, and the image of the current display area is read.
In this example, in the vertical and horizontal (line / pixel) directions of the image of the target display area, the displacement amount V = m / 2 (or V = n /
2) The histogram is calculated when the scroll is performed as described above, that is, when the display image is shifted by half or more of the display image size.

In the creation of the histogram, the frequency of each luminance level value is calculated. Average μ and variance σ of statistics from frequency
² is calculated from Equations 1 and ² , respectively.

[0029]

(Equation 1)

[0030]

(Equation 2)

Here, xi is a pixel value (luminance value of a pixel). Based on the average μ and the variance σ ² , histogram normalization N (μ, σ ² ) is performed, histogram conversion processing is performed, and an LUT is created according to the converted histogram.

FIG. 4 shows an LU according to the histogram conversion method.
FIG. 4 shows an explanatory diagram based on a specific example of T conversion. In the illustrated example, the display image 30b has m lines (= 128) and n pixels (= 1).
28), and a pixel of x _{1, 1} ~x _{128, 128,} the luminance level of each pixel is indicated by the input address table 22. One pixel is one byte (8 bits).

If the displacement of the display area 30a is smaller than the specified value, the control means 21
The switching means 23 is controlled so that the luminance value of each pixel is output only to the LUT conversion means 27. The LUT conversion means 27
The input luminance value of each pixel is sequentially converted using the previous value of the LUT 26, stored in the converted luminance value table 28, and then output to the output display device 5.

On the other hand, when the shift amount of the display area 30a is equal to or more than the specified value, the luminance value of each pixel of the input address table 22 is input to the histogram creating means 24, and the frequency y of the luminance level x is calculated by the histogram conversion. I do. As shown in the histogram table 24a, for example, y = 0 for x = and y = 3 for x = 4.

From the frequency distribution, the average μ and the variance σ ² are calculated by the equations (1) and (2). If the horizontal axis represents the luminance level x and the vertical axis represents the frequency y, a histogram 24b is obtained. Normalization of histogram from mean μ and variance σ ² (μ, σ ² )
Is performed, a histogram 24c having a normal distribution is obtained. In the drawing, x = 0 to 3 levels of the histogram and x
= 252 to 255, the frequency y = 0, and unnecessary information can be deleted.

Next, using the normalized histogram, LU
Update the value of T26. As shown, the brightness levels 0 to
Conversion brightness level = 0, brightness levels 252 to 25 up to 3
Reference numeral 5 designates a converted luminance level 255, and updates the luminance level in between to a luminance conversion level obtained by linear interpolation 26a.

Next, the LUT conversion means 27 converts the luminance level of each pixel in the input address table 22 into the updated LU.
The converted luminance level is converted into the converted luminance level at T26, and stored in the converted luminance value table 28. For example, the pixel value x _1,1 = 10 is x
_The pixel value _x128,126 = 183 becomes _x128,126 = 1 when _1,1 = 5.
Convert to 78.

As described above, in the present embodiment, when the moving amount of the target display area this time is small from the previous time, the LUT conversion is performed by using the previous LUT as it is, so that the processing time until the image is displayed. Can be shortened.
Furthermore, since the calculation of the histogram and the creation of the LUT are performed only for the target display area image, the LUT
The image quality of the displayed image can be optimized as compared with the case where the image is created. As a result, when a continuity of neighboring pixels is strong and a previous LUT can be used without difficulty as in a high-resolution satellite image, a time-consuming histogram creation and LU
The number of T updates can be significantly reduced, and a short-time image display can be realized.

[Embodiment 2] Next, an embodiment in which the present invention is applied to display processing of a three-band color (R, G, B) image will be described. Except for the colorization of the output display device 5, the basic configuration of the image information processing apparatus is the same as that of the first embodiment.

FIG. 5 shows a flowchart of the image processing method according to the present embodiment. First, the maximum value (M or N in the above example) at the time of scrolling is set as the initial value V0 of the displacement amount (S201). When the display area instruction is input (S202), the output position of the current target display area is calculated (S204) while calculating the amount of displacement from the held previous output position (S203). The R band, the G band, and the B band of the area image (m × n) are sequentially input (S205 to S207).

Next, it is determined whether or not the amount of displacement calculated in S203 exceeds a specified value (S208). If it exceeds, a histogram of R band to B band of the display area image is sequentially calculated (S209 to S211). An LUT for each band is created and updated according to each histogram (S212).
The target m × n pixels are subjected to LUT conversion based on the LUT (S213), and the luminance value of the target display area image is output to the display device (S214). On the other hand, if the displacement amount of the target display area is equal to or less than the specified value, LUT conversion is immediately performed. The above method is repeated until scrolling is completed (S21
5).

FIG. 6 is an explanatory diagram showing from the input image to the LUT conversion in the present embodiment. This is the same as FIG. 4 shown in the first embodiment, but the histogram conversion and the LUT update are performed simultaneously for each of the R, G, and B bands to reduce the processing time.

The image 30a 'of the target display area of the designated mxn pixel size is stored in the input address table 22' for each of the R band to the B band. Then, when the movement amount between the first time and the target display area is large, a histogram 24a 'is created for each color, and an LUT 26' is created based on the histograms.

As in the first embodiment, the histogram is calculated by calculating the average μ of the statistic from equation (1) and the variance σ ² from equation ( ² ), and normalizing the histogram by N (μ, σ2). Perform Thereafter, the LUT creation means 2
5 is an LUT2 based on the R, G, and B histograms.
The setting value of 6 'is updated for each band.

According to this embodiment, a color image including the LUT conversion can be displayed with high image quality in a short time. In addition, Lan
Although the dsat satellite observes the earth with 7 bands of multi-bands, the present embodiment can be similarly realized with 4 or more bands of multi-bands.

[Embodiment 3] Next, an embodiment in which the present invention is applied to a case where the luminance level value of an input image is different from that of an output image will be described. The luminance level value of the output display device is s bits,
A system in which the luminance level value of the input image is r bits and the luminance level value of the output display device is lower than that of the input image will be described below.

FIG. 7 shows a flowchart of the image processing method according to the present embodiment. First, the maximum value (M or N in the above example) at the time of scrolling is set as the initial value V0 of the displacement amount (S301). When the display area instruction is input (S302), the output position of the current target display area is calculated (S304) while calculating the amount of displacement from the held previous output position (S303), and the luminance value is calculated. Scale is r
Bit target display area image (m × n pixel) data is input (S305).

Next, it is determined whether the amount of displacement calculated in S303 exceeds a specified value (S306), and if so, a histogram of the display area image is calculated (S307).
The luminance value scale of the histogram is linearly converted (S3
08), an LUT is created (S309). Based on this LUT, the target m × n pixels are subjected to LUT conversion (S31).
0), and outputs the luminance value of the target display area image to the display device (S311). On the other hand, if the displacement amount of the target display area is equal to or less than the specified value, LUT conversion is immediately performed using the previous LUT. The above method is repeated until scrolling is completed (S312).

Here, in the histogram linear conversion process in S308, the r-bit histogram is converted into the s-bit histogram according to Equation 3.

[0050]

(Equation 3)

Here, [rmin, rmax] is an allowable luminance level value of the input image, and [smin, smax] is an allowable luminance level of the output display device.

For example, when 8-bit data per pixel is converted to 6-bit data per pixel of the output display device, 0-bit data of the input image is converted.
The luminance value of 255 is scale-converted to the luminance value of 0 to 63 of the output image.

Thus, even when the luminance scale of the output display device is different from the input image, the scale conversion is performed simultaneously when the LUT is created, so that the number of operations can be reduced. Further, image quality can be ensured according to the input data. In addition, by performing the above-described linear conversion after normalizing the linear histogram, noise can be efficiently removed.

[0054]

According to the present invention, when performing LUT conversion on an input image in a target display area, only when the moving amount of the current input image is larger than a predetermined value, the LUT conversion based on the histogram calculation of the input image is performed. I will update it,
The time for the LUT creation processing in the display processing of large-capacity image data can be greatly reduced, and the display processing can be sped up. Also,
Since the LUT is optimized for the display target area, a high quality display image without blur can be obtained.

Further, when the brightness value scale of the output display device is different from the brightness value scale of the input image, linear conversion is performed simultaneously when the histogram is created, so that the operation can be reduced. In particular, application to a commercially available display device having a small luminance value scale is facilitated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an image information processing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing characteristics of a luminance level of a satellite image.

FIG. 3 is a flowchart of an image information processing method according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of creating a histogram and an LUT in the first embodiment.

FIG. 5 is a flowchart of an image information processing method according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram of creating a histogram and an LUT according to the second embodiment.

FIG. 7 is a flowchart of an image information processing method according to a second embodiment of the present invention.

FIG. 8 is a configuration diagram of a conventional image information processing apparatus including LUT conversion.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image processing apparatus, 3 ... Storage apparatus, 4 ... Display area instruction | indication apparatus, 5 ... Output display apparatus, 10 ... Image input part, 11 ... Target area image input means, 12 ... Output position calculation means, 13
... Transition amount calculating means, 20 ... LUT setting unit, 21 ... Control means, 22 ... Input address table, 23 ... Switching means, 2
4 ... Histogram creation means, 25 ... LUT creation means, 2
6 LUT (lookup table), 27 LUT conversion means, 28 converted luminance value table, 30 satellite image,
30a: display area image, 51: display, 52:
Printer, 53 ... film.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ identification code FI G09G 5/36 520A (58) Investigated field (Int.Cl. ⁷ , DB name) G06T 1/00 510 G06T 1/20 G09G 5 / 06 G09G 5/36 H04N 1/407

Claims (6)

(57) [Claims] 1. An input image of a designated target area is read out from a whole image by a luminance value for each pixel, and image quality is adjusted by LUT conversion based on a set value of a look-up table (hereinafter abbreviated as LUT). When the moving amount of the current target area with respect to the previous target area is smaller than a predetermined value in the processing method of the image information to be output by using the The luminance value of the image is subjected to LUT conversion. If the luminance value of the image is larger than the specified value, the LUT is updated through a predetermined operation such as calculation of a histogram based on the luminance value of the current input image. A method for processing image information, comprising performing LUT conversion. 2. An input image of a designated target area is read out from a whole image by a luminance value for each pixel, and image quality is adjusted by LUT conversion based on a set value of a look-up table (hereinafter abbreviated as LUT). When the moving amount of the current target area with respect to the previous target area is smaller than a predetermined value in the processing method of the image information to be output by using the The luminance value of the image is subjected to LUT conversion. If the luminance value is larger than the specified value, a histogram is calculated based on the luminance value of the current input image, and the set value of the LUT is updated based on the statistical value of the histogram. LUT conversion of the luminance value of the image is performed, and further, a luminance value scale of the input image and a luminance value scale of an output image output after the LUT conversion If different, when calculating the set value of the LUT by the histogram processing method of the image information, characterized in that the linear transformation of the luminance value of the input image to the luminance value scale of the output image. 3. The image information processing apparatus according to claim 1, wherein when the entire image is a multi-band image such as a color image, reading of the input image and calculation of the histogram are performed for each band. Method. 4. A storage device for a whole image, a pointing device for designating an output position, an output display device for displaying or printing an output image of a target area in the whole image, and a look-up table for adjusting image quality (Hereinafter, abbreviated as LUT), and the luminance value of the input image of the target area is represented by L
An image information processing apparatus comprising: an LUT conversion unit that performs UT conversion and outputs the output to the output display device, wherein a movement amount of a current target area with respect to a previous target area is calculated according to an instruction from the instruction device, and the movement amount is calculated. And an image input means for calculating the position of the current target area in the whole image from the input image and reading the input image. If the moving amount is smaller than a predetermined value in the LUT conversion means, , And immediately input L
An image information processing apparatus, comprising: a control unit for performing UT conversion and controlling the LUT to be updated based on a current input image when the LUT is larger than the prescribed value. 5. The LUT conversion unit according to claim 4, wherein the LUT conversion unit has a LUT setting unit that calculates a histogram based on a current input image and calculates a set value of the LUT based on the normalized histogram. Image information processing device. 6. The LUT setting means according to claim 5, wherein said LUT setting means has a luminance value scale conversion processing means for adapting a luminance value of said input image to a luminance value scale of said output display device. Image information processing device.