In addition , the influence mechanism of noise on the enhancement ratio is discussed . from the simulation examples , we find the law that random gaussian white noise influencing synthesized images 另外還分析了噪聲對(duì)分辨率提高倍數(shù)的影響,通過(guò)仿真實(shí)驗(yàn),找到了合成圖像受隨機(jī)高斯白噪聲影響的規(guī)律。
Then the principle and machinery of them are discussed . the fourth step , the experiments of the enhancement ratio of 1 . 5 , 2 and 2 . 5 are carried out . the method of inversion analysis is used for ft ccd and the method of simple pixel cross - interpolation is used for it ccd 對(duì)于行轉(zhuǎn)移ccd ,針對(duì)其盲區(qū)較大的特點(diǎn),可以設(shè)計(jì)較簡(jiǎn)單的象素交叉插值,利用兩幅位移為0 . 5象素的原圖,獲得分辨率提高2倍的高分辨率圖。
From the results of these experiments , we know that the improvement effect is clear when the enhancement ratio is 1 . 5 . but the enhancement ratio of 2 . 5 is difficult to be reached because of the optical dispersion . it shows that the enhancement ratio is limited by the size of ccd sensor ' s cell and optical dispersion 而由于ccd像元尺寸與彌散斑相差不多,要想獲得分辨率提高2 . 5倍的高分辨率圖已經(jīng)很困難,說(shuō)明反演解析法實(shí)際上對(duì)分辨率的提高是有一個(gè)上限的,這和彌散斑與ccd感光像元間的大小比例有關(guān)。
However , the inherent shortcoming of piezoelectric transformer hinders its further development . the major problems include : ( 1 ) the development and design of the piezoelectric transformer involve in lots of theoretic aspects including the design of material , dimension , electrode and circuit ; ( 2 ) it is hard to harvest high voltage enhancement ratio and high - power output simultaneously ; ( 3 ) the operation of the piezoelectric transformer is strongly dependent on the resonance frequency , which leads to the difficulty in the design of driving circuit 但其自身所存在的固有缺點(diǎn)也在很大程度上限制了壓電變壓器的進(jìn)一步發(fā)展,突出的問(wèn)題有:壓電變壓器的研制包括材料設(shè)計(jì)、尺寸設(shè)計(jì)、電極設(shè)計(jì)和電路設(shè)計(jì)等多個(gè)環(huán)節(jié),所涉及的理論面很廣;壓電變壓器的高升壓比和大功率輸出難以同時(shí)得到保證;壓電變壓器的工作過(guò)多地依賴于諧振頻率,為外部電路的設(shè)計(jì)帶來(lái)了困難。