CAJ | 학술논문

地物波谱野外测试过程中常引入噪声.本文结合植物波谱测试原理,提出波谱噪声属于乘性复合噪声.经理论推导,又提出了对数变换与小波变换相结合的降噪方法.仿真降噪试验结果表明,空域相关算法最适合于光谱数据降噪,模极大法次之,阈值法则不适于该类噪声的消减.对野外采集植物波谱的处理结果表明,空域相关去噪法对1450nm附近的噪声去除能力较强,1800～1900nm强噪声则去噪效果不理想.原因在于波谱仪纪录精度有限,当理论比值远大于1时,能够准确记录下来;远小于l时记录值为0,从而在强噪声干扰波段出现较严重的系统误差,经小波降噪后被视作奇异点被保留下来.研究表明对数变换与小波变换相结合采用空域相关去噪对于含乘性复合噪声的光谱是可行的.
지물파보야외측시과정중상인입조성.본문결합식물파보측시원리,제출파보조성속우승성복합조성.경이론추도,우제출료대수변환여소파변환상결합적강조방법.방진강조시험결과표명,공역상관산법최괄합우광보수거강조,모겁대법차지,역치법칙불괄우해류조성적소감.대야외채집식물파보적처리결과표명,공역상관거조법대1450nm부근적조성거제능력교강,1800～1900nm강조성칙거조효과불이상.원인재우파보의기록정도유한,당이론비치원대우1시,능구준학기록하래;원소우l시기록치위0,종이재강조성간우파단출현교엄중적계통오차,경소파강조후피시작기이점피보류하래.연구표명대수변환여소파변환상결합채용공역상관거조대우함승성복합조성적광보시가행적.
The objects' spectrum is often contaminated by noise when it is collected in the open air. According to the principle of the spectrum collection, the noise was considered as one kind of multiplicative compound noise. By theoretical derivation, the combination of logarithm transform and wavelet transform was introduced into noise reduction. Multiplicative noise simulation test was carried out. And the results show that the spatial correlation algorithm is best suited for spectral data denoising, modulus maxima algorithm is inferior to it. Threshold shrinking rule is unsuitable for spectrum denoising. The wild plants spectrum were processed based on spatial correlation algorithm. Results show that the noise near 1450 nm in the spectrum is perfectly denoised, while near 1800 ~ 1900 nm strong noise can not be removed perfectly. The reason is the limited records accuracy of the spectrometer. When the theoretical ratio is far greater than 1, the spectrometer will accurately record them. While the theoretical ratio is far less than 1, the record will be 0. So serious system errors will be generated in strong noise band and will be retained after the wavelet transform was applied because they are considered as signal singularity. Experiments prove that spatial correlative filtering with the combination of logarithm transform and wavelet transform is feasible for multiplicative-noise-contaminated spectrum denoising.