In computing, indexed color is a technique to manage digital images’ colors in a limited fashion, in order to save computer memory and file storage, while speeding up display refresh and file transfers. It is a form of vector quantization compression.
When an image is encoded in this way, color information is not directly carried by the image pixel data, but is stored in a separate piece of data called a palette: an array of color elements. Every element in the array represents a color, indexed by its position within the array. The individual entries are sometimes known as color registers. The image pixels do not contain the full specification of its color, but only its index in the palette. This technique is sometimes referred as pseudocolor or indirect as colors are addressed indirectly.
Perhaps the first device that supported palette colors was a random-access frame buffer, described in 1975 by Kajiya, Sutherland and Cheadle. This supported a palette of 256 36-bit RGB colors.
A thermal imaging camera (colloquially known as a TIC) is a type of the thermographic camera used in firefighting. By rendering infrared radiation as visible light, such cameras allow firefighters to see areas of heat through smoke, darkness, or heat-permeable barriers. Thermal imaging cameras are typically handheld, but may be helmet-mounted. They are constructed using heat- and water-resistant housings, and ruggedized to withstand the hazards of fireground operations.
While they are expensive pieces of equipment, their popularity and adoption by firefighters in the United States is increasing markedly due to the increased availability of government equipment grants following the September 11 attacks in 2001. Thermal imaging cameras pick up body heat, and they are normally used in cases where people are trapped where rescuers cannot find them.
A thermal imaging camera consists of five components: an optic system, detector, amplifier, signal processing, and display. Fire-service specific thermal imaging cameras incorporate these components in a heat-resistant, ruggedized, and waterproof housing. These parts work together to render infrared radiation, such as that given off by warm objects or flames, into a visible light representation in real time.
The camera display shows infrared output differentials, so two objects with the same temperature will appear to be the same “color”. Many thermal imaging cameras use grayscale to represent normal temperature objects, but highlight dangerously hot surfaces in different colors.
Cameras may be handheld or helmet-mounted. A handheld camera requires one hand to position and operate, leaving only one free hand for other tasks, but can be easily transferred between firefighters. The majority of thermal imaging cameras in use in the fire service are handheld models.
The National Institute of Standards and Technology Fire Research division is the lead government agency developing performance standards for fire service thermal imaging cameras in the United States, although the U.S. Army Night Vision Laboratory has contributed to the effort. Preliminary recommendations from the field include visible low-battery warnings, ability to withstand full immersion in water, and the ability to provide meaningful visual readouts beyond 2,000 °F (~1,100 °C).
A thermal imaging camera (colloquially known as a TIC) is a type of the thermographic camera used in firefighting. By rendering infrared radiation as visible light, such cameras allow firefighters to see areas of heat through smoke, darkness, or heat-permeable barriers. Thermal imaging cameras are typically handheld, but may be helmet-mounted. They are constructed using heat- and water-resistant housings, and ruggedized to withstand the hazards of fireground operations.
While they are expensive pieces of equipment, their popularity and adoption by firefighters in the United States is increasing markedly due to the increased availability of government equipment grants following the September 11 attacks in 2001. Thermal imaging cameras pick up body heat, and they are normally used in cases where people are trapped where rescuers cannot find them.
On NOAA POES system satellites, the two images are 4 km / pixel smoothed 8-bit images derived from two channels of the advanced very-high-resolution radiometer (AVHRR) sensor. The images are corrected for nearly constant geometric resolution prior to being broadcast; as such, the images are free of distortion caused by the curvature of the Earth.
Of the two images, one is typically long-wave infrared (10.8 micrometers) with the second switching between near-visible (0.86 micrometers) and mid-wave infrared (3.75 micrometers) depending on whether the ground is illuminated by sunlight. However, NOAA can configure the satellite to transmit any two of the AVHRR’s image channels.
THERMAL SCANNING
Multispectral scanning that is limited to the thermal portion of the EM spectrum.
Provide for very Rapid Results.
To maximize sensitivity, detectors need to be kept artificially cooled(i.e.liquid nitrogen) to near absolute zero.
Interpreting Thermal Scanner Imagery
Applications in:
1.Determining rock types, structure soil types, soil moisture
2.locating water springs, forest fires, subsurface fires.
Qualitative information collection:
1.relative differences in radiant temperatures.
Thermal images, or thermograms, are actually visual displays of the amount of infrared energy emitted, transmitted, and reflected by an object. Because there are multiple sources of the infrared energy, it is difficult to get an accurate temperature of an object using this method. A thermal imaging camera is capable of performing algorithms to interpret that data and build an image. Although the image shows the viewer an approximation of the temperature at which the object is operating, the camera is actually using multiple sources of data based on the areas surrounding the object to determine that value rather than detecting the actual temperature