Color still picture transmission system

A video telephone capable of transmitting a color still picture, comprising:

• a color video camera;
• an interface for converting a color image taken by the color video camera into a luminance signal and color difference signals;
• an analog to digital converter for analog to digital converting the luminance signal an the color difference signals into luminance signal data and color difference signal data, respectively;
• a video memory for storing the luminance signal data and the color difference signal data of at least one screen;
• a color display coupled to the video memory for displaying a color moving picture based upon the data read from the video memory;
• first key input means for acting on the video memory to inhibit the video memory from being altered;
• second key input means for commanding a start of transmission;
• a modem for modulating data to be transmitted;
• a network control circuit for selectively connecting a telephone line to anyone of the modem and a speech telephone;
• a buffer memory for receiving and temporarily storing the luminance signal data and the color difference signal data of a plurality of lines which are read from the video memory;
• first transmitting means for transmitting the luminance signal data of one screen read from the buffer memory onto the telephone line through the modem in response to an operation of the second key input means;
• calculating means coupled to the buffer memory for calculating average data of the color difference signal data of a plurality of adjacent picture elements on the basis of the color difference signal data being temporarily stored in the buffer memory means for each of the color difference signals;
• and
• second transmitting means coupled to the calculating means for sequentially transmitting the average data for each of the color difference signals of the plurality of lines onto the telephone line through the modem until the completion of the transmission of all the lines of one screen, said network control circuit connecting the telephone line to the speech telephone in response to a detection of the completion of transmission of the average data of one screen.