Vision is the term used to describe the ability of the eye to respond to electromagnetic radiation. By definition, light is that part of the electromagnetic spectrum that stimulates the retina of the (human) eye, and the brain, then associates different colors with different wavelengths of the light. Typically, the human eye has the ability to resolve wavelengths extending from the ultra-violet (around 380 nm) to the infrared region of the visible spectrum (around 740 nm).

Even so, color is subjective because the sensitivity to different wavelengths varies significantly between individuals, implying that each person sees a slightly different image when receiving the light scattered or reflected from an object. For the average subject, however, the sensitivity of the normal human eye varies in an approximately Gaussian fashion in daylight, reaching a maximum in the green region of the spectrum. Typically, thousands of different colors can be distinguished. However, modern optical devices show even greater sensitivity and better discrimination between wavelengths than this.

In simple terms, a colored image, for example, captured on a digital camera, is stored as an array of small colored dots (or pixels). These colored dots are represented, first as an electrical charge on the imaging device in response to the characteristics of the incident light, before being transmitted to the digital computer, where both the color and position of the pixels within the image are stored numerically.

Similarly, the number and range of possible colors that can be represented digitally has risen steadily as the numerical precision of digital computers has increased, and corresponding improvements have been made to display monitors and color printers. Again, these factors were discussed in the earlier paper. Many colorful items use could be found in many different resources, check out postallads4free.com as one of sources to view many variety of colors and many other related ads.

In modern measurement systems, a PC is typically used to capture and store the data in digital form. The sensor signals can then be converted from the original input (say a temperature or pressure) into a voltage. These voltage values are then interpreted through detailed analysis, or the observed signals might need to be converted into another form, for example, back into the original pressures or temperatures.

Specialized software also allows the data to be analyzed, for example, to determine how the intensity of the scattered light varies with the wavelength. These advances have revolutionized experimental study, greatly extending the range of properties that can be measured, and enabling better methods of analysis and presentation to be adopted.