History

Digital imaging was developed in the 1960s and 1970s, largely to avoid the operational weaknesses of film cameras, for scientific and military missions including the KH-11 program. As digital technology became cheaper in later decades, it replaced the old film methods for many purposes.

The first digital image was produced in 1920, by the Bartlane cable picture transmission system. British inventors, Harry G. Bartholomew and Maynard D. McFarlane, developed this method. The process consisted of “a series of negatives on zinc plates that were exposed for varying lengths of time, thus producing varying densities,”. The Bartlane cable picture transmission system generated at both its transmitter and its receiver end a punched data card or tape that was recreated as an image.

In 1957, Russell A. Kirsch produced a device that generated digital data that could be stored in a computer; this used a drum scanner and photomultiplier tube.

In the early 1960s, while developing compact, lightweight, portable equipment for the onboard nondestructive testing of naval aircraft, Frederick G. Weighart[3] and James F. McNulty[4] at Automation Industries, Inc., then, in El Segundo, California co-invented the first apparatus to generate a digital image in real-time, which image was a fluoroscopic digital radiograph. Square wave signals were detected by the pixels of a cathode ray tube to create the image.

These different scanning ideas were the basis of the first designs of digital camera. Early cameras took a long time to capture an image and were poorly suited for consumer purposes.[1] It wasn’t until the development of the CCD (charge-coupled device) that the digital camera really took off. The CCD became part of the imaging systems used in telescopes, the first black and white digital cameras and camcorders in the 1980s.Color was eventually added to the CCD and is a usual feature of cameras today.

Methods

A digital photograph may be created directly from a physical scene by a camera or similar device. Alternatively, a digital image may be obtained from another image in an analog medium, such as photographs, photographic film, or printed paper, by an image scanner or similar device. Many technical images—such as those acquired with tomographic equipment, side-scan sonar, or radio telescopes—are actually obtained by complex processing of non-image data. Weather radar maps as seen on television news are a commonplace example. The digitalization of analog real-world data is known as digitizing, and involves sampling (discretization) and quantization.

Finally, a digital image can also be computed from a geometric model or mathematical formula. In this case the name image synthesis is more appropriate, and it is more often known as rendering.

Digital image authentication is an issue[13] for the providers and producers of digital images such as health care organizations, law enforcement agencies and insurance companies. There are methods emerging in forensic photography to analyze a digital image and determine if it has been altered.

Previously digital imaging depended on chemical and mechanical processes, now all these processes have converted to electronic. A few things need to take place for digital imaging to occur, the light energy converts to electrical energy- think of a grid with millions of little solar cells. Each condition generates a specific electrical charge. Charges for each of these "solar cells" are transported and communicated to the firmware to be interpreted. The firmware is what understands and translates the color and other light qualities. Pixels are what is noticed next, with varying intensities they create and cause different colors, creating a picture or image. Finally the firmware records the information for future and further reproduction.

Advantages

There are several benefits of digital imaging. First, the process enables easy access of photographs and word documents. Google is at the forefront of this ‘revolution,’ with its mission to digitize the world’s books. Such digitization will make the books searchable, thus making participating libraries, such as Stanford University and the University of California Berkley, accessible worldwide. Digital imaging also benefits the medical world because it “allows the electronic transmission of images to third-party providers, referring dentists, consultants, and insurance carriers via a modem”. The process “is also environmentally friendly since it does not require chemical processing”. Digital imaging is also frequently used to help document and record historical, scientific and personal life events.

Benefits also exist regarding photographs. Digital imaging will reduce the need for physical contact with original images. Furthermore, digital imaging creates the possibility of reconstructing the visual contents of partially damaged photographs, thus eliminating the potential that the original would be modified or destroyed. In addition, photographers will be “freed from being ‘chained’ to the darkroom,” will have more time to shoot and will be able to cover assignments more effectively. Digital imaging ‘means’ that “photographers no longer have to rush their film to the office, so they can stay on location longer while still meeting deadlines”.

Another advantage to digital photography is that it has been expanded to camera phones. We are able to take cameras with us wherever as well as send photos instantly to others. It is easy for people to us as well as help in the process of self-identification for the younger generation

Aerial Digital Imaging for Agricultural Applications

High Eye Aerial Imaging Inc provides NDVI Imaging services for Ontario's agriculture industry. Our ability to make frequent flights means that images can be taken across different dates to see how a crop / turf has changed over time. Change detection images allow a crop or turf manager to quickly determine if the crop / turf is growing uniformly or if problems exist that are causing the vegetation stress. 

Actionable information that NDVI imaging can provide:

• Chlorophyll levels

• Plant stress and health

• Fertilizer Optimization

• Nitrogen Management Solutions

• Insect and pest plant diagnostics

• Plant disease diagnosis

• Forrest Analysis

• Plant Identification

• Develop farm plan

• Guide cultivation plan

• Guide pruning

• Develop harvest plan based on vigor

Utilizing UAVs for Digital Imaging Analysis (DIA)

Unmanned Aerial Vehicles (UAVs) are an exciting new remote sensing tool capable of acquiring high spatial resolution data. Our UAVs are capable of collecting hyper resolution visible, multispectral, and thermal imagery for application in Precision agriculture. Traditional modes of data collection are not well suited to the detection of subtle but important changes in plant structure given low spatial resolutions. 

Mapping with UAVs has the potential to provide imagery at an unprecedented spatial resolution. Our UAVs have several payload options including visible imagery, which is processed using feature matching and photogrammetric techniques to create Digital Surface Models (DSMs). A thermal infrared camera can be used to map soil moisture enabling assessment of irrigation efficiency, and multispectral camera enables the calculation of vegetation indices that relate to vegetation vigour and health.

Drawbacks

Critics of digital imaging cite several negative consequences. An increased “flexibility in getting better quality images to the readers” will tempt editors, photographers and journalists to manipulate photographs. In addition, “staff photographers will no longer be photojournalistists, but camera operators…as editors have the power to decide what they want ‘shot’^. Legal constraints, including copyright, pose another concern: will copyright infringement occur as documents are digitized and copying becomes easier.

Digital imaging

Digital imaging or digital image acquisition is the creation of digital images, typically from a physical scene. The term is often assumed to imply or include the processing, compression, storage, printing, and display of such images. The most usual method is by digital photography with a digital camera but other methods are also employed.

Raster

Raster images have a finite set of digital values, called picture elements or pixels. The digital image contains a fixed number of rows and columns of pixels. Pixels are the smallest individual element in an image, holding quantized values that represent the brightness of a given color at any specific point.

Typically, the pixels are stored in computer memory as a raster image or raster map, a two-dimensional array of small integers. These values are often transmitted or stored in a compressed form.

Raster images can be created by a variety of input devices and techniques, such as digital cameras, scanners, coordinate-measuring machines, seismographic profiling, airborne radar, and more. They can also be synthesized from arbitrary non-image data, such as mathematical functions or three-dimensional geometric models; the latter being a major sub-area of computer graphics. The field of digital image processing is the study of algorithms for their transformation.

Raster file formats

Most users come into contact with raster images through digital cameras,which use any of several image file formats.

Some digital cameras give access to almost all the data captured by the camera, using a raw image format. The Universal Photographic Imaging Guidelines (UPDIG) suggests these formats be used when possible since raw files produce the best quality images. These file formats allow the photographer and the processing agent the greatest level of control and accuracy for output. Their use is inhibited by the prevalence of proprietary information (trade secrets) for some camera makers, but there have been initiatives such as OpenRAW to influence manufacturers to release these records publicly. An alternative may be Digital Negative (DNG), a proprietary Adobe product described as “the public, archival format for digital camera raw data”.[1] Although this format is not yet universally accepted, support for the product is growing, and increasingly professional archivists and conservationists, working for respectable organizations, variously suggest or recommend DNG for archival purposes.

Vector

Vector images resulted from mathematical geometry (vector). In mathematical terms, a vector consists of point that has both direction and length.

Often, both raster and vector elements will be combined in one image; for example, in the case of a billboard with text (vector) and photographs (raster).

Image viewing

Image viewer software displays images. Web browsers can display standard internet image formats including GIF, JPEG, and PNG. Some can show SVG format which is a standard W3C format.

Some viewers offer a slideshow utility to display a sequence of images.