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Fundamentals of image acquisition and imaging protocol
Published in Michael O’Byrne, Bidisha Ghosh, Franck Schoefs, Vikram Pakrashi, Image-Based Damage Assessment for Underwater Inspections, 2019
Bidisha Ghosh, Michael O’Byrne, Franck Schoefs, Vikram Pakrashi
The RAW image format should be retained for archival purposes. RAW images contain minimally processed data from the image sensor. They are capable of storing a maximum level of information from a scene (i.e., wider dynamic range and color gamut). Post-processing of RAW files allows for all adjustment of exposure, color, and other qualities of the image. The RAW format differs depending on the camera model and camera manufacturer, although each format contains essentially the same data and metadata. An additional step, if desired, would be to convert the original RAW formats to an open standard and well-supported format, namely the digital negative (DNG) format, which is a popular and freely available format developed by Adobe Systems™. Since there is a wide range of proprietary RAW formats, it is hard for applications and programs to guarantee future compatibility with them all, especially for some of the lesser known and lesser used RAW formats. Thus, the additional step of converting to the DNG format from the original RAW format would be of particular value to users that have, or expect to have, imagery acquired from a number of devices, and would like to unify the RAW formats into a common format that retains all of the original information.
Establishing Integrity of Digital Images for Court
Published in Brian E. Dalrymple, E. Jill Smith, Forensic Digital Image Processing, 2018
Brian E. Dalrymple, E. Jill Smith
Adobe offers a free DNG converter that allows users to convert the RAW files from over 350 cameras to a DNG format. This may be useful when using older versions of Adobe Photoshop and shooting images with newer cameras that are not supported in the older software. Find the free converter on Adobe's download page: http://www.adobe.com/support/downloads/.
Dental shade matching assisted by computer vision techniques
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2023
Willian Pulido Beneducci, Marcelo Lucchesi Teixeira, Helio Pedrini
From the practice of digital photography, several authors point out that the use of images in RAW format, such as Digital Negative (DNG), is more recommended than the use of JPEG format (Joint Photographic Experts Group). This is because, in JPEG images, there is compression in which valuable colour information is lost. On the contrary, in RAW format, the image has information that can be easily converted, highlighting important colour information (Jedynakiewicz 2005). In fact, a JPEG image usually has 8 bits that represent each of the three colours; therefore, they usually have 24 bits in total. Each colour has an intensity ranging from 0 to 255. By computing this value for the cube, there is the possibility of representing 16.7 million colours. There are studies that indicate that the human visual system distinguishes between 7 and 10 million colours (Leong 2006). A RAW image, in turn, can have 12 to 14 bits representing each colour channel. It is quite common to find the standard with 12 bits, which can represent up to 4096 possibilities per channel. Adding this value to the cube, it is possible to compute that there are a total number of 68.7 billion achievable colours, which represents 40,000 times more possibilities than the standard JPEG.