Topic
Digital camera
About: Digital camera is a research topic. Over the lifetime, 12169 publications have been published within this topic receiving 137431 citations. The topic is also known as: digicam & digital still camera.
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TL;DR: In this article, a cross-camera calibration procedure that allows concurrent use of an unmodified digital camera and a NIR-sensitive digital camera without preset shutter speeds or aperture settings was proposed.
Abstract: Off-the-shelf consumer digital cameras are convenient and user-friendly. However, the use of these cameras in remote sensing is limited because convenient methods for concurrently determining visible and near-infrared (NIR) radiation using these cameras have not been developed. Two Nikon Coolpix 4300 digital cameras were evaluated in tandem to determine the effectiveness of a cross-camera calibration procedure that would allow concurrent use of an unmodified digital camera and a NIR-sensitive digital camera without preset shutter speeds or aperture settings. The NIR-sensitive camera was modified to detect NIR radiation by replacing the internal hot mirror with a Hoya RM72 filter. Each camera was calibrated at five exposure levels using a Gretag-Macbeth ColorCheckerTM reflectance panel, and raw camera brightness values were converted to relative reflectance by exposure compensation equations. The method was tested on a series of 26 diffuse reflectance targets, which also yielded the same exposure compensation relationships. The relationship between camera channel brightness and target reflectance was nonlinear within each exposure, but sensitivity was linear between exposures. The procedure was tested on 36 cotton plots (Gossypium hirsutum) in an irrigation study in 2006. Images obtained on eight dates during the season were corrected for exposure and converted to relative reflectance values. The normalized difference vegetation index (NDVI) values from the plots were then compared with ground-based spectrometer measurements of NDVI. Corrected camera-based NDVI values were closely correlated with the spectrometer NDVI values (r2 = 0.72), suggesting that the camera system can more consistently estimate crop reflectance characteristics if exposure compensation is applied.
37 citations
Patent•
27 Mar 2010
TL;DR: In this article, a system for taking motion pictures of a scene with different parts at different focal lengths with a camera that normally would not have sufficient depth of field to capture all parts of said scene in focus.
Abstract: A system for taking motion pictures of a scene with different parts at different focal lengths with a camera that normally would not have sufficient depth of field to capture all parts of said scene in focus. A computer (610) controls a high-speed, digital camera (605) and a lens (600) with rapid focus capability to produce a stack of images at different focal lengths for rapid processing into a composite serial image montage stream in motion picture output format (625). Operator controls permit continuous selection of depth of field (DOF) in the output image and enable a plurality of in-focus and out-of-focus regions over the depth of an image. An optional output port (640) provides for real-time recordation of all images in each stack for later processing. An optional remote control (1015) duplicates the main controls in the camera system (1000) so that a second person can assist in optimizing images as they are recorded, or for remote control of the camera itself. An audio input (645) and an optional digital data input (650) are provided for sound and cueing.
37 citations
TL;DR: The results obtained show that PRACTISE is a fast and user-friendly tool, able to derive the microscale variability of snow cover extent in high alpine terrain, but can also easily be adapted to other land surface applications.
Abstract: . Terrestrial photography is a cost-effective and easy-to-use method for measuring and monitoring spatially distributed land surface variables. It can be used to continuously investigate remote and often inaccessible terrain. We focus on the observation of snow cover patterns in high mountainous areas. The high temporal and spatial resolution of the photographs have various applications, for example validating spatially distributed snow hydrological models. However, the analysis of a photograph requires a preceding georectification of the digital camera image. To accelerate and simplify the analysis, we have developed the "Photo Rectification And ClassificaTIon SoftwarE" (PRACTISE) that is available as a Matlab code. The routine requires a digital camera image, the camera location and its orientation, as well as a digital elevation model (DEM) as input. If the viewing orientation and position of the camera are not precisely known, an optional optimisation routine using ground control points (GCPs) helps to identify the missing parameters. PRACTISE also calculates a viewshed using the DEM and the camera position. The visible DEM pixels are utilised to georeference the photograph which is subsequently classified. The resulting georeferenced and classified image can be directly compared to other georeferenced data and can be used within any geoinformation system. The Matlab routine was tested using observations of the north-eastern slope of the Schneefernerkopf, Zugspitze, Germany. The results obtained show that PRACTISE is a fast and user-friendly tool, able to derive the microscale variability of snow cover extent in high alpine terrain, but can also easily be adapted to other land surface applications.
37 citations
TL;DR: In this article, a new technique for detecting damaged tyres employing a standard digital camera that produces JPEG images was proposed, the camera takes pictures of the tyre and if the image size is too large, the tyre is deemed to be with a damage and dangerous for use.
Abstract: Many people die each year in car accidents because of damaged tyres. There are some techniques that have been suggested during the years to detect such tyres. In this paper, we suggest a new technique for detecting damaged tyres employing a standard digital camera that produces JPEG images. The camera takes pictures of the tyre and if the image size is too large, the tyre is deemed to be with a damage and dangerous for use. In such a case an automatic system will draw the driver attention to the tyre condition before a severe accident may happen. The system was checked on many tyres and has high accuracy of damage detection.
37 citations
TL;DR: This work has developed an efficient technique for the recovery of text from digital camera images, which simultaneously treats these three problems, unlike other local thresholding algorithms which do not cope with blur and resolution enhancement.
Abstract: As digital cameras become cheaper and more powerful, driven by the consumer digital photography market, we anticipate significant value in extending their utility as a general office peripheral by adding a paper scanning capability. The main technical challenges in realizing this new scanning interface are insufficient resolution, blur and lighting variations. We have developed an efficient technique for the recovery of text from digital camera images, which simultaneously treats these three problems, unlike other local thresholding algorithms which do not cope with blur and resolution enhancement. The technique first performs deblurring by deconvolution, and then resolution enhancement by linear interpolation. We compare the performance of a threshold derived from the local mean and variance of all pixel values within a neighborhood with a threshold derived from the local mean of just those pixels with high gradient. We assess performance using OCR error scores.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
37 citations