In the process of crack identification for round logs, conventional edge extraction cannot effectively suppress noise because of the tree's annual ring lines and the similarity between the burr noises during cutting and the gray level of the target. Therefore, it is no easy to extract the target crack. The method of continuous gray-scale transformation enhancement is put forward in this thesis to increase the difference between the gray level of the background pixel and the gray level of the target so that can obtain an ideal pre-processed image. In the process of image preprocessing, the method of continuous gray-scale transformation enhancement is applied, that is to combine the gray-scale transformation enhancement and the non-linear filtering process so that can realize the preprocessing of the original image. The gray level difference between the extraction target and the background is increasing under the premise of preserving the image-extraction features. In the extraction process, the extracted target crack image is obtained through utilizing the localization minimum in mathematical morphology and then the compound morphological algorithm is designed based on the basic algorithm of mathematic morphology so as to obtain the target crack image which is connected by the edge curves. Results The MATLAB image processing algorithm is used to simulate each step of the method. The results show that the extracted target crack images are ideal. The mentioned algorit can not only ensure the integrity of the extraction target, but also can suppress the noise very well so that can satisfy the needs during the extraction of complex background images, especially the images with little difference between the background gray level and the extraction target gray level.
Luminance gain is an important parameter to evaluate the light intensity enhancement ability of the low light level image intensifier assembly. The higher the luminance gain, the easier the receiver is to sense and recognize. However, luminance gain is not a directly measurable physical quantity. Thus, luminance gain measuring devices have non-standard specific properties. Based on the principle of luminance gain measuring specified in the standard, the structure and measurement methods of measurement devices are analyzed, the error and optimization methods of two major measurement methods are compared, and the distribution of the combined uncertainty of measuring luminance gain is studied. Then, an optimized measurement scheme of luminance gain of low light level image intensifier assembly is put forward. Based on this scheme, a comprehensive measurement uncertainty analysis is carried out and the calculated luminance gain measurement extended combined uncertainty is about 6.7% (k=2). The results are of great significance for improving the measurement accuracy of luminance gain of low light level image intensifier assembly.
With the view to the requirement of field experiments in Low-Light-Level (LLL) situation, the handheld digital illuminometer is designed based on LLL image intensifier, which is convenient to operate, smaller in size and weight. According to the linear relationship between screen-end current in image intensifier and illuminometer, the screen-end current is designed as signal input. It is converted from analog signals by A/D conversion, and displayed by display unit. Compare with the test data from standard illuminometer, modify MCU (Micro-programmed Control Unit) software. The illuminometer modified can measure the illumination range 10-3 lux to 10-2 lux, meet the demand of measuring in field experiments fundamentally.
It is essential to measure the sensitivity accurately, because sensitivity is an important index of low light level image intensifier for evaluating the photocathode’s responsiveness. In this article, the economic testing equipment has been founded on the method required in the military standards, the way to select parameters of measurement have been shown, and the uncertainty of measurement for testing sensitivity has been analyzed. The expanded uncertainty, which is only below 4.6%, can completely satisfied to the requirement of high precision testing.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.