Evaluation of digital and film hemispherical photography and spherical densiometry for measuring forest light environments

2000 ◽  
Vol 30 (12) ◽  
pp. 1999-2005 ◽  
Author(s):  
Sylvia R Englund ◽  
Joseph J O'Brien ◽  
David B Clark
Keyword(s):  
Image Quality ◽  
Computer Analysis ◽  
Digital Image ◽  
Digital Images ◽  
Optical Quality ◽  
Field Of View ◽  
Canopy Openness ◽  
Hemispherical Photography ◽  
Site Factor ◽  
Film Images

This study presents the results of a comparison of digital and film hemispherical photography as means of characterizing forest light environments and canopy openness. We also compared hemispherical photography to spherical densiometry. Our results showed that differences in digital image quality due to the loss of resolution that occurred when images were processed for computer analysis did not affect estimates of unweighted openness. Weighted openness and total site factor estimates were significantly higher in digital images compared with film photos. The differences between the two techniques might be a result of underexposure of the film images or differences in lens optical quality and field of view. We found densiometer measurements significantly increased in consistency with user practice and were correlated with total site factor and weighted-openness estimates derived from hemispherical photography. Digital photography was effective and more convenient and inexpensive than film cameras, but until the differences we observed are better explained, we recommend caution when comparisons are made between the two techniques. We also concluded that spherical densiometers effectively characterize forest light environments.

scholarly journals Robust Gaussian Noise Detection and Removal in Color Images using Modified Fuzzy Set Filter

2020 ◽  
Vol 30 (1) ◽  
pp. 240-257
Author(s):  
Akula Suneetha ◽  
E. Srinivasa Reddy
Keyword(s):  
Image Quality ◽  
Mean Square Error ◽  
Fuzzy Set ◽  
Digital Image ◽  
Gaussian Noise ◽  
Digital Images ◽  
Structural Similarity ◽  
Fuzzy Rules ◽  
Mean Square ◽  
Image Edges

Abstract In the data collection phase, the digital images are captured using sensors that often contaminated by noise (undesired random signal). In digital image processing task, enhancing the image quality and reducing the noise is a central process. Image denoising effectively preserves the image edges to a higher extend in the flat regions. Several adaptive filters (median filter, Gaussian filter, fuzzy filter, etc.) have been utilized to improve the smoothness of digital image, but these filters failed to preserve the image edges while removing noise. In this paper, a modified fuzzy set filter has been proposed to eliminate noise for restoring the digital image. Usually in fuzzy set filter, sixteen fuzzy rules are generated to find the noisy pixels in the digital image. In modified fuzzy set filter, a set of twenty-four fuzzy rules are generated with additional four pixel locations for determining the noisy pixels in the digital image. The additional eight fuzzy rules ease the process of finding the image pixels,whether it required averaging or not. In this scenario, the input digital images were collected from the underwater photography fish dataset. The efficiency of the modified fuzzy set filter was evaluated by varying degrees of Gaussian noise (0.01, 0.03, and 0.1 levels of Gaussian noise). For performance evaluation, Structural Similarity (SSIM), Mean Structural Similarity (MSSIM), Mean Square Error (MSE), Normalized Mean Square Error (NMSE), Universal Image Quality Index (UIQI), Peak Signal to Noise Ratio (PSNR), and Visual Information Fidelity (VIF) were used. The experimental results showed that the modified fuzzy set filter improved PSNR value up to 2-3 dB, MSSIM up to 0.12-0.03, and NMSE value up to 0.38-0.1 compared to the traditional filtering techniques.

Digital Imaging Exposure-Time Optimisation of Tripod-Camera Vibrating Systems Based on MTF

2008 ◽  
Author(s):  
Giulio Fanti ◽  
Roberto Basso
Keyword(s):  
Image Quality ◽  
Exposure Time ◽  
Digital Image ◽  
Digital Imaging ◽  
Digital Images ◽  
Noise Sources ◽  
Initial Analysis ◽  
Vibrating System ◽  
Time Optimization ◽  
Vibrating Systems

The problem of exposure-time optimization in digital images acquired by a tripod-camera vibrating system is examined in this paper and an initial analysis is presented. The different noise sources concerning both the acquisition sensor in the camera and external vibrations were studied and quantified in some specific cases. The digital image quality is then discussed in terms of the MTF function evaluated at 50% level in order to define what the optimum ranges of exposure-times are.

scholarly journals Evaluation of hemispherical photos extracted from smartphone spherical panorama images to estimate canopy structure and forest light environment

2020 ◽  
Author(s):  
A. Z. Andis Arietta
Keyword(s):  
Image Quality ◽  
Forest Canopy ◽  
Dynamic Range ◽  
Canopy Structure ◽  
High Dynamic Range ◽  
Canopy Openness ◽  
Traditional Methods ◽  
Area Index ◽  
Site Factor ◽  
High Dynamic

AbstractHemispherical photography (HP) is one of the most commonly employed methods to estimate forest canopy structure and understory light environments. Traditional methods require expensive, specialized equipment, are tedious to deploy, and are sensitive to exposure settings. In contrast, modern smartphone cameras are readily available and make use of ever-improving software to produce images with high dynamic range and clarity, but lack suitable hemispherical lenses. Thus, despite the fact that almost all ecologists and foresters carry a high-powered, image processing device in our pockets, we have yet to fully employ it for the purpose of data collection. As an alternative, hemispherical images can be extracted from spherical panoramas produced by many smartphone camera applications. I compared hemispherical photos captured with a digital single lens reflex camera and 180° lens to those extracted from smartphone spherical panoramas (SSP) for 72 sites representing a range of canopy types and densities. I estimated common canopy and light measures (canopy openness, leaf area index, and global site factor) as well as image quality measures (total gap area, number of gaps, and relative gap size) to compare methods. The SSP HP method leverages built-in features of current generation smartphones including exposure metering over restricted field-of-view, high dynamic range tonal correction, computational sharpening, high pixel density, and automatic leveling via the phone’s built-in gyroscope to yield an accurate alternative to traditional HP in canopy estimation. Although the process of stitching together multiple photos occasionally produces artifacts in the SSP HP images, estimates of canopy openness and global site factor are highly correlated with those of traditional methods (R2> 0.9) and are comparable to under- or over-exposing traditional HP by 1-1.5 stops. In addition to superior image quality, SSP HP requires no additional equipment or exposure settings and is likely to prove more robust to uneven lighting conditions by avoiding wide-angles lenses and exploiting HDR images.

scholarly journals Manipulacion De La Imagen Digital En Medicina. Conceptos Basicos Para Médicos.

2019 ◽  
Vol 38 (2) ◽  
Author(s):  
Rolando Reyna
Keyword(s):  
Image Quality ◽  
Digital Image ◽  
Digital Images ◽  
Good Choice ◽  
File Size ◽  
Multimedia Presentations ◽  
Scanned Image ◽  
Joint Photographic Experts Group ◽  
Digital Manipulation ◽  
Small File

<p><strong>[Manipulation Of The Digital Image In Medicine. Basics Concepts For Doctors]</strong></p><p> </p><div><br />Resumen<br />Las imágenes digitales en medicina son importantes hoy en día por su uso en diferentes campos. La manipulación de imágenes juega un importante rol en las presentaciones.</div><div>Las funciones más importantes para obtener imágenes son el tamaño, resolución y color. Resoluciones de 300 ppp y 72 ppp deben ser usadas para publicaciones y presentaciones por computadoras, respectivamente. La imagen debe ser salvada en formato TIFF la cual es un tipo de archivo que no comprime imágenes.</div><div>El formato JPG comprime el tamaño de la imagen pero reduce su calidad. El formato JPG es una buena opción si se necesita, como en Internet o una presentación de PowerPoint.</div><div> </div><div> </div><div>Abstract<br />The digital images in medicine are very important today in different fields. Digital manipulation of images plays a key role in development of multimedia presentations.</div><div>The most important functions for properly scanning images are size, resolution, and color. Resolutions of 300 ppi and 72 ppi should be used for print publication and computer presentations, respectively. The scanned image should be saved as a TIFF, which is an uncompressed file. The Joint Photographic Experts Group (JPEG) format compresses the size of the image file but also reduces image quality.</div><div>The JPEG format is a good choice if a small file size is needed, such as in Web and PowerPoint presentations.</div>

The reliability of digital images when used to assess burn wounds

2003 ◽  
Vol 9 (1_suppl) ◽  
pp. 22-24 ◽  
Author(s):  
O C Jones ◽  
D I Wilson ◽  
S Andrews
Keyword(s):  
Image Quality ◽  
Digital Image ◽  
Digital Images ◽  
Burn Wounds ◽  
Partial Thickness ◽  
Partial Thickness Burns ◽  
Burn Depth ◽  
Better Than ◽  
Good Agreement ◽  
Made In

summary Sixty burn wounds were assessed in person. The same observer later assessed them using digital images of different sizes. The file sizes tested were 2.25, 5.5 and 9 MByte per image. There was good agreement between the diagnoses of burn depth made using the digital images and those made in person, with kappa scores of 0.53–0.60. There were no major differences between the three file sizes. The assessments made of the partial-thickness burns showed a lower rate of agreement between the in-person and the digital image assessments and for these burns the 2.25 MByte images were apparently as good or better than the larger images. There was little difference between the three file sizes in terms of observer confidence, usefulness of the location shot, or perceived image quality. There was no significant advantage in using larger file sizes to assess burn wounds.

scholarly journals A DENOISING OF BIOMEDICAL IMAGES

2015 ◽  
Vol XL-5/W6 ◽  
pp. 73-78 ◽  
Author(s):  
D. N. H. Thanh ◽  
S. D. Dvoenko
Keyword(s):  
Image Quality ◽  
Total Variation ◽  
Digital Image ◽  
Gaussian Noise ◽  
Digital Images ◽  
Poisson Noise ◽  
Biomedical Images ◽  
Biomedical Image ◽  
Digital Devices ◽  
Imaging Science

Today imaging science has an important development and has many applications in different fields of life. The researched object of imaging science is digital image that can be created by many digital devices. Biomedical image is one of types of digital images. One of the limits of using digital devices to create digital images is noise. Noise reduces the image quality. It appears in almost types of images, including biomedical images too. The type of noise in this case can be considered as combination of Gaussian and Poisson noises. In this paper we propose method to remove noise by using total variation. Our method is developed with the goal to combine two famous models: ROF for removing Gaussian noise and modified ROF for removing Poisson noise. As a result, our proposed method can be also applied to remove Gaussian or Poisson noise separately. The proposed method can be applied in two cases: with given parameters (generated noise for artificial images) or automatically evaluated parameters (unknown noise for real images).

Authentication of Digital Image using Exif Metadata and Decoding Properties

2018 ◽  
pp. 335-341 ◽  
Author(s):  
D. P. Gangwar ◽  
Anju Pathania
Keyword(s):  
Digital Image ◽  
Digital Images ◽  
Software Tools ◽  
Robust Analysis

This work presents a robust analysis of digital images to detect the modifications/ morphing/ editing signs by using the image’s exif metadata, thumbnail, camera traces, image markers, Huffman codec and Markers, Compression signatures etc. properties. The details of the whole methodology and findings are described in the present work. The main advantage of the methodology is that the whole analysis has been done by using software/tools which are easily available in open sources.

PERBANDINGAN METODE MD4 DAN SHA 384 UNTUK MENDETEKSI ORISINALITAS CITRA DIGITAL

2019 ◽  
Vol 3 (1) ◽  
Author(s):  
Lemcia Hutajulu ◽  
Hery Sunandar ◽  
Imam Saputra
Keyword(s):  
Digital Image ◽  
Detrimental Effect ◽  
Digital Images ◽  
Computer Crime ◽  
The Other ◽  
Image Manipulation ◽  
The Internet ◽  
Secret Key

Cryptography is used to protect the contents of information from anyone except those who have the authority or secret key to open information that has been encoded. Along with the development of technology and computers, the increase in computer crime has also increased, especially in image manipulation. There are many ways that people use to manipulate images that have a detrimental effect on others. The originality of a digital image is the authenticity of the image in terms of colors, shapes, objects and information without the slightest change from the other party. Nowadays many digital images circulating on the internet have been manipulated and even images have been used for material fraud in the competition, so we need a method that can detect the image is genuine or fake. In this study, the authors used the MD4 and SHA-384 methods to detect the originality of digital images, by using this method an image of doubtful authenticity can be found out that the image is authentic or fake.Keywords: Originality, Image, MD4 and SHA-384

scholarly journals Digital Graphic Documentation and Architectural Heritage: Deformations in a 16th-Century Ceiling of the Pinelo Palace in Seville (Spain)

2021 ◽  
Vol 10 (2) ◽  
pp. 85
Author(s):  
Juan Reinoso-Gordo ◽  
Antonio Gámiz-Gordo ◽  
Pedro Barrero-Ortega
Keyword(s):  
20Th Century ◽  
Digital Image ◽  
Digital Images ◽  
Laser Scanner ◽  
16Th Century ◽  
Southern Europe ◽  
Architectural Heritage ◽  
Digital Documentation ◽  
First Time

Suitable graphic documentation is essential to ascertain and conserve architectural heritage. For the first time, accurate digital images are provided of a 16th-century wooden ceiling, composed of geometric interlacing patterns, in the Pinelo Palace in Seville. Today, this ceiling suffers from significant deformation. Although there are many publications on the digital documentation of architectural heritage, no graphic studies on this type of deformed ceilings have been presented. This study starts by providing data on the palace history concerning the design of geometric interlacing patterns in carpentry according to the 1633 book by López de Arenas, and on the ceiling consolidation in the 20th century. Images were then obtained using two complementary procedures: from a 3D laser scanner, which offers metric data on deformations; and from photogrammetry, which facilitates the visualisation of details. In this way, this type of heritage is documented in an innovative graphic approach, which is essential for its conservation and/or restoration with scientific foundations and also to disseminate a reliable digital image of the most beautiful ceiling of this Renaissance palace in southern Europe.

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