共查询到18条相似文献，搜索用时 134 毫秒
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在人造卫星观测的ＣＣＤ图象记录中，为方便图象保存，查阅及图象处理，将图象记录中的相关信息插入记录的图象中是十分重要的。ＹＴＩ－Ａ视频时码插入器正是为此应用而设计。本仪器内有一个可自动与后面板输入秒同步到１μｓ的数字钟。记录日期包括年月日，时刻记录精度为１０μｓ，望远镜指向（Ａ，ｈ）的记录精度为１″。这些信息全部以二种格式被插入记录的图象中可供图象处理时查阅和快速读出。文中叙述了仪器原理及应用 相似文献
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在人造卫星观测的ＣＣＤ，图象记录中，为方便图象保存，查阅及图象处理，将图象记录中的相关信息插入记录的图象中是十分重要的，ＹＴＩ－Ａ视频时码插入器正是为此应用而设计，本仪器内有一个可自动与后面板输入秒同步到１μｓ的数字钟。记录日期包括年月日，时刻记录精度为１０μｓ，望远镜指向（Ａ，ｈ）的记录精度为１″，这些信息全部以二种格式被插入记录的图象中可供图象处理查阅和快速读出，文中叙述了原理及应用。 相似文献
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本文着重指出了在今后处理大面积CCD图象数据过程中,所将面临的数据存贮困难问题.本文提出了一种有效的不丢失天文信息的压缩CCD图象数据的方法,对银纬b=-60°的一个天区的试验表明,压缩后的图象数据仅为原图象数据的1/30左右,并且可以十分方便地进行图象再现及再处理。在压缩数据过程中,我们在剑桥APM底片扫描机参数化施密特照相底片的基础上,重新安排了CCD图象上天体的对应参数,并视天体的大小及形状,有效地提取保存了天体周围矩阵信息. 相似文献
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讨论了经过大气后天文图象的象质衰减,研究了对这种衰减进行描述的视宁度参数ｒ０及其它几个大气光学参数,介绍了几种测量象质衰减参数的方法,重点介绍了我们将差分像运动法运用于白日视宁度测量的尝试以及新设计的可兼顾昼夜的视宁度测量仪,仪器已用于云台白日的视宁度测量。最后对近场近似假设进行了定量分析,在此基础上给出了新确定的近场近似成立的范围,这一范围比以前所给的要更大些。 相似文献
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The increasing use of data compression by space mission experiments poses the question of quality of the images obtained after the compression-decompression process. Indeed, working on an Image Compression Module (ICM), Using Discrete Cosine Transform (DCT), with 8*8 pixel-sized sub-images (each pixel being coded on eight bits), one can find blocking effects on their boundaries. Avril and Nguyen (1992, thereafter ANG 1992), have shown that One Neighbour Accounting Filters, used after image reconstruction without modifying the coding method , provide the best and fastest correction as far as linear filtering is concerned. We present here a non-linear method, also used after image reconstruction, but working on spatial frequencies. It allows us to segregate, in the Fourier space, the signal from the defect, and then to remove it through applying a filter adapted to the frequency spectrum of each spoiled image. Employing the reverse Fourier transform, we then retrieve the corrected image. The efficiency of this new method was tested by three different means:- when Fourier filtering is applied to a reference set of aerial photographs of the Earth, blocking effects are quite indistinguishable by human vision, even when zooming on the images, which was not the case with ONAF;- the improvement of the Root Mean Square (RMS) Error, calculated between the filtered and original images, is at least three times greater than the one obtained with ONAF;- the reconstruction of a three-dimensional view of a landscape, thanks to two stereoscopic images having undergone a compression-decompression process with an algorithm using DCT and a compression rate of about 10, is possible only after Fourier filtering has been applied.The quite good preliminary results of the application of Fourier filtering to the Clementine images of the Moon are also represented. 相似文献
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《Chinese Astronomy and Astrophysics》2019,43(3):405-423
Due to the atmospheric turbulence, the static aberration, tracking and pointing errors of telescopes, the point spread functions (PSFs) in different fields of view are different. Meanwhile, there are different PSFs in the images obtained by different telescopes. The quality of co-adding image is limited by the image with the poorest quality, and finally the resolution and sensitivity of the quad-channel telescope will also be affected. Dividing the image into some regions with the same type of PSF, and deconvolving these regions can improve the quality of the co-adding image. According to this theory, an image restoration algorithm based on the PSF clustering is proposed. Firstly, this paper makes the PSF clustering analysis by using Self-Organizing Maps, and makes the image segmentation based on the result of the PSF clustering analysis, then using the clustered PSFs to make deconvolutions on the sub-images. Then, the restored sub-images after deconvolution are joined together. Finally, by through the image registration and co-adding, the image with a high signal to noise ratio can be obtained. The result shows that the signal to noise ratio of the astronomical images are improved with our method, and the detection capability on faint stars is also improved. 相似文献
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以往由于内存小,CCD的读出过程需小块读出,随时存盘;而且由于小块读出中间停顿,数据质量差;尽管现在超过1兆的微机已相当普遍,然而普通操作系统的内存管理仍局限于640k。目前CCD器件的尺寸越来越大,使这一矛盾变得越来越尖锐。针对这些问题,本文介绍一种用扩充内存作图象数据缓冲区的图象采集处理系统方案,并给出具体实现步骤。 相似文献
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本文介绍了ＴＩＦＦ图象文件的文件结构和从ＴＩＦＦ格式文件复原图象的方法，以及该图象在ＴＶＣＡ上的各种调色板的设置及显示。 相似文献
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We present a procedure to extract bright loop features from solar EUV images. In terms of image intensities, these features
are elongated ridge-like intensity maxima. To discriminate the maxima, we need information about the spatial derivatives of
the image intensity. Commonly, the derivative estimates are strongly affected by image noise. We therefore use a regularized
estimation of the derivative, which is then used to interpolate a discrete vector field of ridge points; these “ridgels” are
positioned on the ridge center and have the intrinsic orientation of the local ridge direction. A scheme is proposed to connect
ridgels to smooth, spline-represented curves that fit the observed loops. Finally, a half-automated user interface allows
one to merge or split curves or eliminate or select loop fits obtained from this procedure. In this paper we apply our tool
to one of the first EUV images observed by the SECCHI instrument onboard the recently launched STEREO spacecraft. We compare
the extracted loops with projected field lines computed from near-simultaneous magnetograms measured by the SOHO/MDI Doppler
imager. The field lines were calculated by using a linear force-free field model. This comparison allows one to verify faint
and spurious loop connections produced by our segmentation tool and it also helps to prove the quality of the magnetic-field
model where well-identified loop structures comply with field-line projections. We also discuss further potential applications
of our tool such as loop oscillations and stereoscopy. 相似文献