The conversion between RGB and YUV image Video format

Monitor Image Display Overview:

We know that there are three electronic guns in the ordinary color CRT display, electronic gun to activate the fluorescent powder of the monitor screen, three kinds of phosphor emit light to generate a pixel position color point, this is our human eye can see a pixel. Each pixel corresponds to red, green, blue (R, G, B) Three intensity levels, each pixel occupies 24 bits, can display nearly 17 million kinds of colors, this is what we call True color.

Ordinary color CRT display is based on the television technology raster scan, the electron beam scanning one line at a time, from the top to the end of the scan, the entire screen scanning once (we call it 1 frames), the electron beam after a frame scan back to the original position for the next scan.

TV Image Display Overview:

TV display principle is similar to CRT, but uses interlaced scanning, our country's broadcast television uses is 625 rows interlaced scanning way. Interlaced scanning is a two-time (field) scan of a frame image. First sweep out 1, 3, 5, 7 ... such as odd-numbered line grating, the second sweep out 2, 4, 6, 8 ... Equal even line grating. The field called odd fields (also called the field) that sweeps odd-numbered rows is called even number field (also known as the end). Why does the TV choose interlaced scanning because it makes the display of moving images smoother. The following two images are the first and next scanning processes for a frame image.

(Figure 1 on-field scan)

(Figure 2 Next scan)

The common television standard has three kinds: NTSC, pal, SECAM, our country's broadcast television uses the PAL standard, our country television standard frame frequency only 50HZ and our daily use current frequency is same, the PAL frame frequency is 25fps, At the end of the article I will use a 720x576 image to convert to 720x 576 PAL interlaced video format of the television scene for detailed description.

RGB Introduction:

In the recording of computer images, the most common is the use of RGB (red, green, blue) color components to save color information, such as uncompressed 24-bit BMP image on the use of RGB space to save the image. One pixel 24 bits, each 8 bit preserves a color intensity (0-255), for example, Red is saved as 0xff0000.

YUV Introduction:

YUV is a color coding method adopted by European television system, which is widely used in Chinese radio and television. where "Y" indicates brightness (luminance or luma), which is the gray-scale value, and "U" and "V" represent chroma (chrominance or chroma). Color TV using YUV space is precisely to use the brightness signal y to solve the color TV and Black-and-white TV compatibility problem, so that black-and-whites can also receive color TV signal.