Introduction to image sources

The principle energy source for images in use today is the electromagnetic energy spectrum. Other important sources of energy include acoustic, ultrasonic and electronic. Unlike humans, who are limited to the visual band of the electromagnetic spectrum, imaging machines cover almost entire electromagnetic spectrum, ranging from gamma to radio waves. They can operate on images generated by sources that humans are not accustomed to associating with images. These include,

• Ultra sound imaging.
• Gamma ray imaging.
• X-ray imaging.
• Imaging in an ultraviolet band.
• Imaging in the visible and infrared bands.
• Imaging in the microwave band.
• Imaging in the radio band.
• Electron microscopy.

figure 1: Electromagnetic spectrum