GROUP OF PIGEONS
Pigeons and doves constitute the animal family Columbidae and the order Columbiformes, which includes about 42 genera and 310 species. The related word "columbine" refers to pigeons and doves. They are stout-bodied birds with short necks, and short slender bills that in some species feature fleshy ceres. They primarily feed on seeds, fruits, and plants. This family occurs worldwide, but the greatest variety is in the Indomalaya and Australasia ecozones. Pigeons and doves are likely the most common birds in the world. The distinction between "doves" and "pigeons" is not consistent. In modern everyday speech, as opposed to scientific usage or formal usage, "dove" frequently indicates a pigeon that is white or nearly white. However, some people use the terms "dove" and "pigeon" interchangeably. In contrast, in scientific and ornithological practice, "dove" tends to be used for smaller species and "pigeon" for larger ones, but this is in no way consistently applied. Historically, the common names for these birds involve a great deal of variation between the terms. The species most commonly referred to as "pigeon" is the species known by scientists as the rock dove, one subspecies of which, the domestic pigeon, is common in many cities as the feral pigeon.
Chroma key compositing, or chroma keying, is a special effects / post-production technique for compositing (layering) two images or video streams together based on color hues (chroma range). The technique has been used heavily in many fields to remove a background from the subject of a photo or video – particularly the newscasting, motion picture and videogame industries. A color range in the foreground footage is made transparent, allowing separately filmed background footage or a static image to be inserted into the scene. The chroma keying technique is commonly used in video production and post-production. This technique is also referred to as color keying, colour-separation overlay (CSO; primarily by the BBC), or by various terms for specific color-related variants such as green screen, and blue screen – chroma keying can be done with backgrounds of any color that are uniform and distinct, but green and blue backgrounds are more commonly used because they differ most distinctly in hue from most human skin colors. No part of the subject being filmed or photographed may duplicate the color used as the backing.