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Color image processing for digital cameras
Published in Sharma Gaurav, Digital Color Imaging Handbook, 2017
Most megapixel consumer cameras use the Exif11 image format, which is based on the JPEG standard.47 The Exif files are named and organized into folders using the DCF standard.48 DCF requires that the color image be interpreted as sRGB image data to ensure interoperability. In addition to the JPEG compressed image data, the Exif file stores various metadata describing the camera and picture-taking conditions.49 The metadata include the time and date, camera zoom position and focus distance, illumination level, camera calibration data, subject, and copyright owner. The metadata can be used to simplify image retrieval and provide higher-quality prints from the digital files.50 The Exif metadata include a thumbnail-size image at the beginning of the JPEG file to allow groups of images to be rapidly viewed so that appropriate images can be quickly selected for viewing, copying, or printing.
Semantic Enrichment for Automatic Image Retrieval
Published in Spyrou Evaggelos, Iakovidis Dimitris, Mylonas Phivos, Semantic Multimedia Analysis and Processing, 2017
Clement H. C. Leung, Yuanxi Li
Location data: Cameras having a built-in GPS receiver will automatically capture the location data and store it in the Exif header when the image is taken. In addition, GPS data can be retroactively added to any digital photograph, either by correlating the time stamps of the photographs with a GPS time-dependent record from a hand-held GPS receiver or manually using a map or mapping software.
CEP: calories estimation from food photos
Published in International Journal of Computers and Applications, 2020
Hong Liang, Yuan Gao, Yunlei Sun, Xiao Sun
The approach proposed by Akpa et al. [15] is to use a mobile phone camera to take a food photo and take two chopsticks next to the food container as a reference object to estimate the food container based on the EXIF metadata (camera focal length and sensor size) of the food image in order to estimate the size and the volume of food, according to food density and nutrient information obtained by the type of food to estimate calories. For weight estimation, the average relative error rate was 6.65% and the calorie estimated relative error rate was 6.70%. Akpa does not implement automatic food recognition, so users still need to select a recognition area. A phone is only used as a shooting device while computing job needs to be uploaded to the backend server, which may affect the user experience in a poor network environment. Likewise, their job is also focusing on calorie estimation of the food prepared in a restaurant.
Unmanned aerial vehicle inspection of the Placer River Trail Bridge through image-based 3D modelling
Published in Structure and Infrastructure Engineering, 2018
Ali Khaloo, David Lattanzi, Keith Cunningham, Rodney Dell’Andrea, Mark Riley
Once features have been detected throughout the data-set, the features are matched across an image pair using the multithreaded implementation of the Fast Approximate Nearest Neighbours (FANN) algorithm (Muja & Lowe, 2014). Using Exchangeable Image Format (EXIF) metadata embedded in each digital image to extract values of the focal length and image size, a fundamental matrix (F-matrix) (Hartley & Zisserman, 2004) is fitted to all the features in the image pair based on the epipolar geometry, in tandem with RANSAC (RANdom SAmple Consensus) (Fischler & Bolles, 1981) and the eight-point algorithm to remove outliers and false matches (Hartley & Zisserman, 2004). To illustrate, Figure 4 shows the extracted and matched SIFT feature points on sample images from Placer River Bridge.
Volunteered remote sensing data generation with air passengers as sensors
Published in International Journal of Digital Earth, 2021
Chisheng Wang, Yongquan Wang, Leyang Wang, Zhongwen Hu, Shaobiao Zhang, Shuanglong Wang, Wenqun Xiu, Hongxing Cui, Dan Wang, Qingquan Li
In addition to the camera positioning information, approximate interior orientation parameters, including the focal length and the sensor size, are also needed to facilitate conjugate point searching. Currently, most of new digital camera automatically saves EXIF data with the photo. The focal length, camera manufacturer and model number are typically included in the EXIF data. With the camera model number, the sensor size can be found from the product specification file (normally available in the website of manufacturer). Also, the interior camera orientation parameters will be further refined in the next step.