CN100395526C - Data compressing method of interference superspectrum imaging instrument - Google Patents

Abstract

The present invention relates to an interference type data compressing method of a super-spectrum imaging instrument; an interference figure is generated by a super-spectrum imaging instrument; the data of the interference figure is transferred to a data compressing module to cut the interference figure; an interference figure signal in a large information quantity near the zero optical path difference is separated; the interference figure signal in a large information quantity near the zero optical path difference is directly downloaded; the interference figure signal with high optical path difference is sent to the compressing module; the interference figure signal with high optical path difference is compressed and then is downloaded; the interference figure signal which is compressed and downloaded is decompressed; the interference figure signal is reconsolidated with the interference figure signal to newly form an integral interference figure; finally, optical spectrum restoration is carried out. The present invention solves the technical problem that the distortion of the compressed interference figure is high so a true optical spectrum can not be recovered in the background art. The present invention has the advantages of rapid calculation speed, little distortion after compression and decompression and good effect; besides, the working reliability is greatly improved.

Description

The interference type super spectrum imager data compression method

Technical field

The present invention relates to a kind of interference type super spectrum imager data compression method.

Background technology

The interference type spectral imaging technique comprises spatial modulation type, time modulation type and space and time common modulation type etc., and rise the nineties in the world.The interference type spectral imaging belongs to the remote sensing observations technology, because resource-constrained on the satellite can not carry out handling on the star, must be transferred on the ground and handle.Simultaneously, the data volume that inteference imaging spectrometer produces is very big, does not do directly transmission of compression, and the bandwidth of following biography passage also can't meet the demands.What interference type super spectrum imager produced is the interferogram data, is different from general image data, and the interferogram data just can obtain the HYPERSPECTRAL IMAGERY sequence that the user can directly use as intermediate result after must restoring through software on ground.Interferogram has certain distortion after compression, if drop-out is too much, or lost the part important information, then can't restore real spectrum.Can cause bigger distortion and adopt the normal image compression method that interferogram is compressed.

The data compression technique of spaceborne interference type super spectrum imager is only seen the method based on autoregression AR model that has the Frenchman to propose at present, belongs to lossy compression method.The parametric model that it at first sets up interferogram calculates one group of parameter that characterizes interferogram.Modelling is just represented a kind of method of interferogram, and is much more succinct than the method with undressed sample direct representation in this way, but distortion simultaneously is in company with the also corresponding generation of compression, promptly occurs in the process to the quantification of parameter, residual error and coding.Adopt the AR model that interferogram is compressed, reach degree of distortion ^[1]Requirement, its shortcoming is the calculating process complexity, arithmetic speed is slow, especially as product on the star, very big with hard-wired difficulty, reliability is low.

Summary of the invention

It is bigger to the invention solves in the background technology distortion of compression interferogram, can't restore the technical matters of real spectrum.

Technical solution of the present invention is:

A kind of interference type super spectrum imager data compression method, its special character is: this method comprises

1). produce interferogram by hyperspectral imager, the data of interferogram are sent to data compressing module;

2). interferogram is cut apart, be divided near bigger interferogram signal and the big interferogram signal of optical path difference of quantity of information of zero optical path difference;

3). the interferogram signal that near the quantity of information zero optical path difference is bigger is separated, and keeps motionless, directly passes down: the interferogram signal that optical path difference is big, deliver to compression module;

4). the interferogram signal that optical path difference is bigger is compressed, passed down then;

5). interferogram reconstruction: decompress to compressing the interferogram signal that passes under the back, itself and the direct interferogram signal of biography are down reconsolidated, reconstitute complete interferogram;

6), spectrum recovering: the interferogram after the reconstruct is sent into land information system, finish spectrum recovering.

Above-mentioned the bigger interferogram signal of optical path difference is compressed, can be adopted uniform quantization method and 9PCM method to compress; Also can adopt the normal image compression method to compress.

Above-mentioned normal image compression method is good to adopt the uniform quantization method.

The present invention has the following advantages:

1. compression method of the present invention proposes according to the characteristics of interferogram, and principle is clear and definite, and calculating process is simple;

2. fast operation;

3. hard-wired difficulty is very little;

4. the degree of distortion after compressed and decompressed is little, and effect is good;

5. adopt prior art integrated in a large number, the reliability of working on the star improves greatly.

Description of drawings

Accompanying drawing is a process flow diagram of the present invention.

Embodiment

Referring to accompanying drawing.The present invention be directed to its degree of distortion index of a kind of compression method of interference type super spectrum imager data and the index of Y-PSNR and all can satisfy index request.Flow process is as follows

1. produce interferogram by hyperspectral imager: produce the interferogram data by instrument and be sent to data compressing module;

2. interferogram is cut apart: according to the character of interferogram, the interferogram signal that near the quantity of information zero optical path difference is bigger is separated, and keeps motionless, directly passes down; The remaining big interferogram signal of optical path difference is delivered to compression module;

3. the bigger interferogram signal of optical path difference is compressed: can adopt uniform quantization method and DPCM method to compress, can also adopt the method for normal image compression is compressed, as the uniform quantization method ^[3], pass down then;

4. interferogram reconstruction: decompress to compressing the interferogram signal that the back passes down, itself and the interferogram signal that directly passes are down reconsolidated, reconstitute complete interferogram;

5. spectrum recovering: the interferogram after the reconstruct is sent into land information system, finish spectrum recovering.

Degree of distortion: provide the grade estimation standard to the method that is adopted, need reasonably estimate the limits of error of spectrum.Be a grade estimation standard below, also be called spectrum relative mean square error RQE (Relativespectral Quadratic Error):

$\mathrm{RQE}=\frac{\sqrt{{\∫}_0^{0.5}{|\hat{S}\left(\tilde{f}\right)-S\left(\tilde{f}\right)|}^{2}d\tilde{f}}}{{\∫}_0^{0.5}S\left(\tilde{f}\right)d\tilde{f}}$

In the formula:

Be original spectrum;

Be the spectrum of rebuilding after compression; $\tilde{f}=\frac{1}{\mathrm{\&lambda;}{f}_e}$ Be the normalization frequency $(0<\tilde{f}<0.5);$ λ is wavelength (the μ m of unit); f _eBe sample frequency.

By analysis, the noise in the interferogram mainly is a photon noise, and in visible light and near infrared range, the corresponding fiducial interval of its RQE is 2%～4%.Therefore, the variance of photon noise can be used as the reference that allows distortion when compressing.

The definition of Y-PSNR: PSNR

$\mathrm{PSNR}=10\log \frac{(N1\&times;N2)\&times;{(A-1)}^2}{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{(x_i-y_i)}^2}$

In the formula: N1, N2 are respectively the line number and the columns of detector, and A is a peak value, if promptly adopt 12bit to quantize, peak value is 4095; X is an original image; Y is the image after compressed and decompressed.

The interferogram that hyperspectral imager collects quantizes with 12bit, if quantize with 8bit or 10bit, also can reach certain compression ratio.The abundant information that near zero optical path difference sampled point carries, amplitude is bigger, and will be used for doing the phase place correction, and the bigger part of optical path difference belongs to high-frequency information, after through first difference filtering, its amplitude is very little.Therefore, after amplitude rounded, be equivalent to adopt uniform quantizer, can quantize, write down its symbol with 1bit again, so just can significantly compress, reach the purpose of compression with 3bit.

Claims (2)

1. interference type super spectrum imager data compression method, it is characterized in that: this method comprises

1). produce interferogram by hyperspectral imager, the data of interferogram are sent to data compressing module;

2). interferogram is cut apart, be divided near bigger interferogram signal and the big interferogram signal of optical path difference of quantity of information of zero optical path difference;

3). the interferogram signal that near the quantity of information zero optical path difference is bigger is separated, and keeps motionless, directly passes down; The interferogram signal that optical path difference is big is delivered to compression module;

4). the interferogram signal that optical path difference is bigger is compressed, passed down then;

5). interferogram reconstruction: decompress to compressing the interferogram signal that passes under the back, itself and the direct interferogram signal of biography are down reconsolidated, reconstitute complete interferogram;

6). spectrum recovering: the interferogram after the reconstruct is sent into land information system, finish spectrum recovering.

2. interference type super spectrum imager data compression method according to claim 1 is characterized in that; Described the bigger interferogram signal of optical path difference is compressed, adopted uniform quantization method and DPCM method to compress.

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