Optoelectronic remote sensing systems collect images in the optical range of electromagnetic waves. They are sensitive to visible and infrared wavelengths.
The panchromatic band is a grayscale image that covers the red, green, and blue portions of the electromagnetic spectrum (0, 45-0, 90 m), therefore they are black and white. Satellites of the new generation of high and very high resolution, as a rule, acquire images in both panchromatic and multispectral modes.
By examining the strength of reflection, we can understand a conditions of land surface, e.g., distribution of plants, forests and farm fields, rivers, lakes, urban areas. Optoelectronic images can’t depict information during period of darkness and over cloudy areas.
Spatial resolution is considered as the most important parameter of optoelectronic image and can be defined as the smallest discernible detail in an image. The factors that impact spatial resolution are the parameters of optoelectronic system, as well as the orbit height, i.e. the distance from the satellite to the shooting subject. The best spatial resolution is achieved during collection at the nadir, when a satellite deviates from nadir the resolution is getting worse.
Radiometric resolution describes its ability to discriminate very slight differences in the recorded energy. It is determined by the number of color gradations corresponding to the change from absolute "black" to a completely "white", and is expressed in bits per pixel. This means that when the radiometric resolution is 6 bits per pixel, which is only 64 color gradation, 8 bits per pixel - 256 color gradations, 11 bits per pixel - 2048 color gradations.