Photographic Density Research Articles

Investigation of the Long-term Variation of Solar Ca ii K Intensity. I. Density-to-intensity Calibration Formula for Historical Photographic Plates

Abstract This paper presents a novel formula to convert photographic density into intensity for historical photographic plates of the Sun. Photographic photometry is of great importance as the very first step of analyzing century-long archived photographic data to study the long-term variation. The calibration formula is newly developed by using the intensity fluctuation originating in the network pattern in the quiet region, taking into consideration the nonlinearity between the density and the intensity. The formula is useful especially when experimentally obtained characteristic curves are insufficient for homogeneous analysis of a whole long-term data set. An example procedure of the calibration using the formula is demonstrated. Resultant intensity images calibrated from the photographic data can reproduce both the fluctuation and the center-to-limb variation of modern reference data. The calibration procedure is also tested with a whole twentieth century data set and shows good performance, while the preliminary result of the long-term intensity variation seems to be partially affected by the quality of the original plates. The resultant solar Ca II K intensity variation will be updated and discussed in a subsequent paper with the comparison to the solar UV variation related to the terrestrial environment.

Heuristic self-photography approach for flat-top beam generation with arbitrary beam intensity distribution

Flat-top beam (FTB) is a type of laser illumination with broad applications. To achieve an easily accessible and cost-effective flat-top intensity profile, a self-photography approach was developed in this study. Utilizing the linear region of the Hurter–Driffield (H&D) curve, we developed an analytical formulation and simulation approach for FTB power optimization with a Gaussian beam (GB) and other intensity profiles. Notably, when a GB profile was used, the maximum transmission efficiency of an FTB depended on the lowest photographic density within the linear region of the H&D curve. Various beam profiles and experimental conditions were evaluated through numerical simulations. We performed experiments to verify the simulation results, which exhibited power efficiency of up to 14.89 % when using a GB. Current beam reshaping techniques use phase modulation; our self-photography method provides an alternative approach to generating uniform illumination with arbitrary intensity profiles, regardless of beam coherence properties. This newly developed cost-effective film approach can be easily incorporated into systems without excessive additional components. This straightforward implementation can be adapted for various illumination needs, such as high-order beam modes and multiple beam sources.

Image Data Acquisition for Estimating Individual Trees Metrics: Closer Is Better

Background and Objectives: The recent use of Structure-from-Motion with Multi-View Stereo photogrammetry (SfM-MVS) in forestry has underscored its robustness in tree mensuration. This study evaluated the differences in tree metrics resulting from various related SfM-MVS photogrammetric image acquisition scenarios. Materials and Methods: Scaled tri-dimensional models of 30 savanna trees belonging to five species were built from photographs acquired in a factorial design with shooting distance (d = 1, 2, 3, 4 and 5 m away from tree) and angular shift (α = 15°, 30°, 45° and 60°; nested in d). Tree stem circumference at 1.3 m and bole volume were estimated using models resulting from each of the 20 scenarios/tree. Mean absolute percent error (MAPE) was computed for both metrics in order to compare the performance of each scenario in relation to reference data collected using a measuring tape. Results: An assessment of the effect of species identity (s), shooting distance and angular shift showed that photographic point cloud density was dependent on α and s, and optimal for 15° and 30°. MAPEs calculated on stem circumferences and volumes significantly differed with d and α, respectively. There was a significant interaction between α and s for both circumference and volume MAPEs, which varied widely (1.6 ± 0.4%–20.8 ± 23.7% and 2.0 ± 0.6%–36.5 ± 48.7% respectively), and were consistently lower for smaller values of d and α. Conclusion: The accuracy of photogrammetric estimation of individual tree attributes depended on image-capture approach. Acquiring images 2 m away and with 30° intervals around trees produced reliable estimates of stem circumference and bole volume. Research Highlights: This study indicates that the accuracy of photogrammetric estimations of individual tree attributes is species-dependent. Camera positions in relation to the subject substantially influence the level of uncertainty in measurements.

Field detection of material defect of dry transformer winding

To detect the material defect of dry transformer winding, a series of study were carried out concerning about the law of absorption ray intensity of matter, detection methods and procedures and Photographic density variation rule of copper and aluminium. The field detection was also conducted in residential area without preliminary treatment.

Early diagnosis of jaw osteomyelitis by easy digitalized panoramic analysis

BackgroundOsteomyelitis is an intraosseous inflammatory disease characterized by progressive inflammatory osteoclasia and ossification. The use of quantitative analysis to assist interpretation of osteomyelitis is increasingly being considered. The objective of this study was to perform early diagnosis of osteomyelitis on digital panoramic radiographs using basic functions provided by picture archiving and communication system (PACS), a program used to show radiographic images.MethodsThis study targeted a total of 95 patients whose symptoms were confirmed as osteomyelitis under clinical, radiologic, pathological diagnosis over 11 years from 2008 to 2017. Five categorized patients were osteoradionecrosis, bisphosphonate-related osteonecrosis of jaw (BRONJ, suppurative and sclerosing type), and bacterial osteomyelitis (suppurative and sclerosing type), and the control group was 117 randomly sampled. The photographic density in a certain area of the digital panoramic radiograph was determined and compared using the “measure area rectangle,” one of the basic PACS functions in INFINITT PACS® (INFINITT Healthcare, Seoul, South Korea). A conditional inference tree, one type of decision making tree, was generated with the program R for statistical analysis with SPSS®.ResultsIn the conditional inference tree generated from the obtained data, cases where the difference in average value exceeded 54.49 and the difference in minimum value was less than 54.49 and greater than 12.81 and the difference in minimum value exceeded 39 were considered suspicious of osteomyelitis. From these results, the disease could be correctly classified with a probability of 88.1%. There was no difference in photographic density value of BRONJ and bacterial osteomyelitis; therefore, it was not possible to classify BRONJ and bacterial osteomyelitis by quantitative analysis of panoramic radiographs based on existing research.ConclusionsThis study demonstrates that it is feasible to measure photographic density using a basic function in PACS and apply the data to assist in the diagnosis of osteomyelitis.

Novel Mixture of Materials Produces Bone- and Soft Tissue-Like Imaging Density

The objective of the present study was to access to imaging material density close to or identical density imaging of bone and soft tissue, from raw materials of nature to be used in different model applications and to provide comprehensive evaluation of the imaging system and techniques under realistic conditions in radiology departments for educational purposes. The palm tree of abundance in Saudi Arabia was chosen to study the date’s seeds and palm leaves in terms of photographic density. The results achieved were referring to the lack of imaging density of dates seeds and palm leaves compared to bone density. Thus, it was necessary to use two additional materials: Salt and eggshells in order to find the highest density and graphic approach to bone density. The present preliminary study indicated that the permanent and stable model can be achieved by palm leaves, salt & eggshell powder with imaging material density close to the imaging density of the bone and soft tissue for achieving more clinical skills and medical education.

「錯視現象」が胸部ＣＴ画像の気胸の診断能に及ぼす影響 ‐視覚心理学的シミュレーションによる実証‐

Some cases have been reported in which an optical illusion of lightness perception influences the detectability in diagnosis of low-density hematoma in head CT images in addition to the visual impression of the photographic density of the brain. Therefore, in this study, the author attempted to compare the detectability in diagnosis for chest images with pneumothorax using visual subjective evaluation, and investigated the influence of optical illusion on that detectability in diagnosis. Results indicated that in the window setting of lung, on such an occasion when the low-absorption free space with pneumothorax forms a crescent or the reduced lung borders on the chest-wall, an optical illusion in which the visual impression on the difference of the film contrast between the lung and the low-absorption free space with pneumothorax was psychologically emphasized when contrast was observed. In all cases the detectability in diagnosis for original images with the white thorax and mediastinum was superior to virtual images. Further, in case of the virtual double window setting of lung, thorax, and mediastinum, under the influence of the difference in the radiological anatomy of thorax and mediastinum as a result of the grouping theories of lightness computation, an optical illusion different from the original images was observed.

「錯視現象」が頭部ＣＴ画像の診断能に及ぼす影響―明るさ知覚に関する錯視現象の画像診断への関与―

Even if the visual impression of the photographic density of the brain in head CT images is shown as physically the same, it is known that optical illusions of lightness perception (assimilation, contrast, picture frame effect, etc.) occur and that practical density can be observed psychologically differently, according to differences in the color of the skull and background, and differences in cases (differences in picture pattern). Therefore, in this study, in order to clarify the influence of optical illusion on detectability in diagnosis, the author attempted to compare detectability in four sample cases, consisting of acute cerebral infarction (1), acute epidural hematoma (1), and chronic subdural hematoma (2), using visual subjective evaluation. In the case of acute cerebral infarction, there was no significant difference in detectability between the original image and the virtual images. Further, it clarified that the original head CT image (acute epidural hematoma) with the high-density hematoma recognized at the marginal limited part of the brain was inferior to virtual images in detectability, while it clarified that the original head CT image (chronic subdural hematoma) with the low-density hematoma was superior to virtual images in detectability, because of visual psychological emphasis on the difference of the film contrast between the hematoma and white skull.

Visual impression of photographic density of lung, thorax, and mediastinum in chest CT images: verification of optical illusion by visual subjective evaluation of medical images

Even if the brain in head CT images is shown physically at the same photographic density, optical illusion (assimilation, contrast, etc.) occurs and practical density can be observed psychologically differently. Therefore, in this study, in order to clarify the visual characteristics of lightness perception in chest CT images, I attempted to compare it with the visual impression of the photographic density of lung, thorax, and mediastinum, using visual subjective evaluation. The results were as follows. (1) In the case of the preferential window setting of lung, both thorax and mediastinum, which surround the lung, are recognized as a wide white frame with contrast, and the photographic density of the lung psychologically seems blackish as a result of the "picture frame effect". (2) In the case of the preferential window setting of thorax and mediastinum, the visual impression of the photographic density varies among observers. (3) In the case of the virtual double window setting of lung, thorax, and mediastinum, under the influence of both high-density and low-density areas in the radiological anatomy of thorax and mediastinum, the photographic density of lung psychologically appears whitish as a result of the "grouping theories" of lightness computation. Further, under the influence of original gray lung, the photographic densities of thorax and mediastinum psychologically appear to be whitish.

Digital Test Pattern法によるCRの階調カーブ測定

Computed radiography (CR) has many variations in gradation, and it is difficult to grasp all of them. We produced the Digital Test Pattern, a step chart made based on digital values that was created by personal computer using Binary Editor. Image data input in the CR system is replaced with the Digital Test Pattern data. A gradation curve is measuring for using the processed output image data in the CR system, such that we can determine the relation between input and output. We termed this the Digital Test Pattern method. Output characteristics after gradation processing are obtained by output signal value and input signal value. Input is known beforehand, and change in the gradation processing parameter is understood from the output pixel value. It is also possible to measure a gradation curve directly from photographic density. Measuring the relation of input and output enabled computer simulation of a gradation curve. These studies indicated the effectiveness of our proposed method in terms of accuracy and ease of use.

Visual impression of photographic density of the brain in head CT images: verification of optical illusion by visual subjective evaluation of medical images

The purpose of this study was to clarify the psychological influence of optical illusion on the photographic density of the brain in head CT images. In this study, I attempted to compare the visual impression of photographic density of the brain using visual subjective evaluation according to observers and cases. The results showed that the visual impression of photographic density of the brain at cerebellar CT depended upon the mode of appearance of the optical illusion (assimilation, contrast, picture frame effect, etc.). In addition, that impression varied according to differences in cases (difference of picture pattern) and observers. Further, it was clarified that the optical illusion had been observed according to individual differences among observers. Moreover, cases could be divided into two main classes. Some cases were recognized as a kind of outline figure (the white skull was recognized as an induction color, and the brain as a non-induction color) with assimilation, and consequently the brain seemed whitish. In other cases (the white skull was not recognized as an induction color) in which there was no assimilation, the brain did not seem whitish. This was considered to have occurred because the degree of influence of the skull on the visual impression of the photographic density of the brain had changed according to differences in cases.

A comparative study on the photographic density of root canal materials when taking a photograph by X-ray in the dental use

A comparative study on the photographic density of root canal materials when taking a photograph by X-ray in the dental use

頭部CT画像における「枠の効果」の検証 : 頭部CT画像の脳実質写真濃度についての心理学的検討

When reading and diagnosing head CT images, it is not always clear whether or not the optical illusion known as the "picture frame effect" is present. In order to examine this phenomenon, I used personal computer image processing application software to create head CT images that look upon the skull and the background of the image as a single frame. Second, I tried to compare them using the visual subjective evaluation of nine observers. The results were then analyzed statistically. Because of the differences between frames, the discriminative ability of the human visual system (contrast/assimilation) could determine whether the picture frame effect was taking place. Even if the brain was shown at exactly the same photographic density, sometimes the plural frame in the image would leave a whitish impression on the observer and sometimes it would leave a blackish impression ; thus, it would seem that the practical density had been observed differently. Therefore, photographic density is under the influence of the frame that occasionally surrounds the image. In the future, we should further consider the "picture frame effect."

バルーンを用いた写真濃度による拡散反射率の簡易推定法

バルーンを用いた写真濃度による拡散反射率の簡易推定法

Evaluation of Signal Detectability with Lung Nodular Reproduction by ROC Analysis using Photographic Density

Evaluation of Signal Detectability with Lung Nodular Reproduction by ROC Analysis using Photographic Density

Aerial Films and Solar Angles: Influences on Silver Sagebrush Inventory

Aerial photos in Alberta are generally acquired according to topographic mapping and forestry specifications. The parameters for interpreting rangeland vegetation, such as silver sagebrush (Artemisia cana-Pursch), need to be explored and condensed into an operational specification. Five aerial films and 3 solar angles were evaluated by 7 photo interpreters to determine the optimal conditions for interpreting silver sagebrush at a scale of 1:20,000. Interpreter accuracy and preference are determined for the 2 experimental conditions as to determine operational specifications. Kodak Panatomic-X 2412 achieved the highest interpretation accuracies for silver sagebrush cover detection and plant density estimation (91.0% and 94.4% respectively), while Kodak Aerochrome Infrared 2443 and Agfa Avicolor H100 performed best for estimating plant vigor (92.7% and 93.7% respectively). Photo interpreters also chose Kodak Panatomic-X 2412 as the preferred film for interpreting silver sagebrush (7.7 on a scale of 10). Positive correlations were obtained between combinations of interpretation accuracy, interpreter film preference and photographic density range measurements, indicating the trends for higher accuracy and preference are associated with higher density ranges. Solar angles of 20 degrees, 37 degrees and 54 degrees were evaluated by photo interpreters with significant preference shown for 20(.). Recommendations for modifying Alberta's air photo operational specifications to include high resolution (Kodak Panatomic-X) imagery and decreasing the acceptable lower boundary for the operational solar angle from 30 to 20 degrees for interpreting silver sagebrush at the 1:20000 scale are proposed.

Studies on the photographic density of the root canal filling material when taking a photograph by X-ray in the dental use

Studies on the photographic density of the root canal filling material when taking a photograph by X-ray in the dental use

Identification of forest stands by aerial photographic density

Identification of forest stands by aerial photographic density

435. CR画像における最適圧縮率の基礎的検討 第2報 : 写真濃度特性の評価

435. CR画像における最適圧縮率の基礎的検討 第2報 : 写真濃度特性の評価

"New" B and V Photometry of the "Old" Type IA Supernova SN 1937C: Implications for HO

view Abstract Citations (33) References (60) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS "New" B and V Photometry of the "Old" Type IA Supernova SN 1937C: Implications for HO Pierce, Michael J. ; Jacoby, George H. Abstract We have digitized and analyzed the original Baade and Zwicky 18 in. Palomar Schmidt films of the type Ia supernova SN 1937C. The data set consists of 76 films in the photographic bandpass mpg and a series of 50 previously unreduced photovisual (m_pv_) films. These data were supplemented by the three known, prediscovery plates of SN 1937C taken by Leutenegger and Grenat. The films and plates were scanned using the KPNO PDS microdensitometer and calibrated by fitting the integrated photographic density to a magnitude sequence of local standards on each film/plate. The resulting calibrations have typical rms dispersions of 0.06 and 0.04 mag for m_pg_ and m_pv_, respectively. Our magnitudes at the earliest epochs are systematically 0.30 mag fainter than those reported by Baade & Zwicky, with the two datasets converging by the eighth observation, about 11 days after maximum. We converted our mpg and mpv photometry to B and V using transformations determined both theoretically using synthetic photometry of spectrophotometric standards, and empirically using the local standard stars. The B and V light curves and B - V color evolution of SN 1937C were fitted with template light curves from previously well-observed supernovae to obtain B_max_= 8.94+/- 0.03, V_max_ = 9.00+/-0.03, and (B - V)_B(max)_ = -0.08 +/- 0.04. These correspond to M(B_max_)= - 19.42 and M( V_max_)= - 19.36 when combined with the Cepheid distance to IC 4182, the host galaxy. In comparing our results with the visual photometry of Beyer we found evidence for a color term which when applied to Beyer's data, leads to V_max_ = 8.87. We stress the importance of determining accurate color terms in the photometry of SN Ia due to the wide color range (from B - V ~ 0 to B - V ~1) through which they evolve over the first 30 days after maximum. The SN 1937C light curves were best fit by templates with very slow rates of decline. The correlation between decline rate and luminosity implies that SN 1937C, with {DELTA}m_15_ = 0.85 mag, was as much as 0.44 mag more luminous than average SN Ia and that it was one of the most intrinsically luminous SN Ia studied to date. The luminosity calibration for SN 1937C was applied to the Hubble relation derived by Hamuy et al. for which distant SNe magnitudes were corrected for their decline rates. This calibration of the SN Ia distance scale yields a Hubble Constant between H_0_ = 68+/-5 km s^-1^ Mpc^-1^ and H_0_ = 74+/-6 km s^-1^ Mpc^-1^, depending on the choice of slope for the decline rate relation. Publication: The Astronomical Journal Pub Date: December 1995 DOI: 10.1086/117737 Bibcode: 1995AJ....110.2885P Keywords: SUPERNOVAE: INDIVIDUAL: SN 1937C; ISM: ABUNDANCES full text sources ADS | data products SIMBAD (8) NED (2)