JPS6288067A - Processing method for data from artificial satellite - Google Patents

Abstract

PURPOSE:To obtain a pseudo color picture in which a chroma saturation is intensified by converting the picture signal of an RGB color display system to that of an HSV color display system, intensifying the chroma saturation in the HSV color display system, and converting again the picture signal to the one of the RGB color display system. CONSTITUTION:The digital data of TM bands 1-3 from an artificial satellite are corresponded to blue (B), green (G), and red (R) respectively, and for the first, a standardization is performed in the range from the lower limit of 0 to the upper limit 1, to find a level frequency. And based upon the above, the data of the RGB color display system is converted to the H(hue), S(chroma saturation), and V(brightness) color display system. Next, a level strength process is applied only on the chroma saturation (S) and the data of the HSV color display system after the level stretch process is converted reversely to that of the RGB color display system. Thereby, a pseudo color data in which the saturation is intensified can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a method for processing data from an artificial satellite, and in particular to a method for processing data from an artificial satellite such as Landsat.
M: Thematic Mapper, hereinafter TM
This invention relates to an improvement in a method for processing data (abbreviated as "abbreviation") to create a false color image.

[Conventional examples and their problems] Pseudo-color images created based on TM data transmitted from artificial satellites such as Landsat are used to investigate and observe geology, land use status, water environment, etc. .

It is extremely important for those who interpret pseudo-color images to be able to easily identify and distinguish objects from the pseudo-color images. For this purpose, it is necessary to emphasize the saturation (or saturation and brightness) among the saturation, brightness, and hue of the created pseudocolor image.

As is well known, to create a pseudocolor image, first, three desired bands are selected from a plurality of TM bands, the selected TM bands are made to correspond to red, green, and blue, and a level frequency distribution map of each TM band is created. do. However, conventionally, this level frequency distribution data is simply subjected to line formation or nonlinear contrast-stretching processing to create a pseudocolor image, which makes it impossible to increase saturation (and brightness). There wasn't. For this reason, there is a problem in that it is not easy to identify and discriminate objects from pseudo-color images.

[Objective] The present invention provides a data processing method that emphasizes saturation (or both saturation and brightness) when processing TM data transmitted from an artificial satellite to create a pseudo-color image. That's true.

[Main points of the present invention] In order to achieve this objective, the present invention first transforms an image signal of RGB (red/green/blue) color system into HSV (hue, saturation,
(brightness) color system, emphasizes the saturation (or both saturation and brightness) in the HSV color system, and converts the image signal again to the RGB color system to obtain a pseudo-color image. There is.

[Embodiment] An embodiment of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 is a flowchart for explaining the present invention. The present invention relates to image data processing in the area surrounded by the broken line 10 in FIG. Image data conversion to system, block 14
indicates data processing for color enhancement, and block 16 indicates a processing step of inverse conversion of image data from the HVS color system to the RGB color system. , and the method of its inverse transformation itself is well known.

As is well known, digital data from an artificial satellite (Landsat) is composed of seven bands TM1 to TM7 classified by wavelength. (Landsara) - Data users depending on the purpose of interpretation? Ii [Create an image by selecting the appropriate band. In Figure 1, TM band
TM band 3, blue (B), green (G), φred (
A case is shown in which an R◆GB output is obtained using the image signal processing method according to the present invention. Incidentally, the pseudo-color image is the output of the flowchart shown in FIG.
- Created based on G-B output.

The digital data included in each TM band contains information on each point divided into a matrix, and 256 (0 to 256)
255) level. T like this
First, the M-band data is standardized to a range with a lower limit of O and an upper limit of 1, and a level frequency distribution is determined.

Figure 2 (A), (B), and (C) show TM bands 1 to 3, respectively.
This is a diagram (example) showing the level frequency distribution after standardizing the data. Now, the data of one point (b, g, r) consisting of TM band l, 2.3 is TM band 1. Data b= 0.25 (a)T
Assume that M band 2 data g=, 0.10 (b) TM band 3 data r= 0.50 (e).

Maximum value of (a), (b), and (c) above (m a x)
is 0.50, the minimum value (min) is O, lO (7) C'
, V (lightness) of the HSV color system is max 0, 5
becomes.

When m a x in the equations (a), (b), and (c) above is not 0, S (saturation) of the HSV color system is determined by the following formula.

s = (wax-min)/max = (0,5-0,1)10.5 =O08 On the other hand, when m a x in the above (a), (b), and (c) is O, S (saturation) = 0, in this case h (hue)
is indefinite.

If S is not O, (max-r)/(max-m, in) is expressed as r for convenience.
C, and (max-g)/(max-mf n) is expressed as gc for convenience.
For convenience, (max-b)/(max-min) is bc
given that.

rc=0 gc=1 bc=0.625.

Since the above-mentioned max is r (red) data, the following calculation is performed (h' is an intermediate value (rotation angle information) for determining h (hue) in the HSV color system).

h'=bc-gc=0.825-1 --0.375 (For example, in the above explanation, if g (green) is the maximum value, h'=rc-bc+2 (7) Equation On the other hand, using
When b (blue) is the maximum value, the following calculation formula is used: h'=gc-rc+4. ) If h' is negative, the hue (h) in the HSV color system is.

Using the formula h=h' shall be.

Therefore, b, g, r as above (a) (b) (c)
If we assume as follows, V (brightness) and s(
Saturation) and h (hue) are: v=0.5 (0≦V≦1) s=0.8 (0≦S≦1) h=337.5° (0≦h≦3600), and as described above. The image data of one point was converted from the RGB color system to the HSV color system. The results (level frequency distributions of v, s, and h) obtained by performing such a conversion operation on all image points are as shown in FIGS. 3(A), 3(B), and 3(C), for example.

Next, data other than hue (h) data, ie.

Perform level (linear) stretching processing on only saturation (5) or both saturation (s) and brightness CV), that is, only in Fig. 3 (B) or in Fig. 3 (A) and (
Figure 4 (B) is subjected to level stretch processing.
A) and (B) are diagrams showing the level frequency distribution after linear stretching processing (conversion) is performed on the level frequency distribution shown in FIGS. 3(A) and CB). Note that the level stretch processing is a well-known processing method, so a description thereof will be omitted.

Next, using the hsv data after the level stretch processing, the HSV color system is inversely converted to the RGB color system. V and S data after level stretch processing.

If v = 0.6 s = 0, 9 (no level stretch processing is performed on h, h = 337.5°) h' = h/60 = 337.5760 = 5.625 becomes.

The integer value (referred to as i) of h' is 5, and the decimal part (referred to as f) is 0.625.

Now, p=vX (L-s) q = vX (1-(sXf) If t=vX (1-(sX C1-f)).

p=0.06 q=0.2625 t=0.3975 becomes.

As mentioned above, the integer value of h' (referred to as i) is 5, so r = v = 0.6 q = p = O, 0S 1) = q = o, zszs, and the data of the H5V color system is The data is converted to RGB color system data. That is, TM band 1 data: b=0.25 is converted to 0.2625, TM band 2 data: g=O, lO is converted to 0.06, TM band 3 data: r=0. 50 was converted to 0.60.

Perform the above processing operations on all image points, and then
Data in the color system is converted to the H5V color system to emphasize saturation (saturation and brightness), and then converted back to data in the RGB color system to create a pseudo-color image.

[Effect] As explained above, according to the data processing method of the present invention, it is possible to obtain a pseudo-color image that emphasizes saturation or both saturation and brightness, so It is extremely useful for investigating and observing the environment.

[Brief explanation of drawings]

Figure 1 is a flowchart for explaining the present invention, Figure 2 is a flowchart for explaining the present invention;
Figures 4 through 4 are level frequency diagrams for explaining the present invention. In the figure, 10 indicates data processing according to the present invention, and 12.1
4.16 respectively indicate the data processing according to the invention with the reference number IO.

Claims (1)

[Claims] A method for creating a pseudo-color image by processing a plurality of channel data transmitted from an artificial satellite, including: (a) selecting three types of channel data; (b) Obtain level frequency distribution for each of the above channel data, (c) RGB (red, green, blue) color system image data. ,H
Convert to image data in SV (hue, saturation, brightness) color system, (d) Emphasize only saturation or saturation and brightness in HSV color system, (e) HSV color system A method for processing data from an artificial satellite, characterized by converting the image data of the image data into RGB color system image data again to obtain a pseudo-color image.