Colour recovery from B&W kinescope films

[cbenham]

Originally Posted by Joel Cairo

So the short answer is: assuming the kinescope film was properly and professionally transferred, the full frames are all there-- it's just that their respective fields are slightly jumbled in places...
-Kevin

This thread began as a discussion of the process by which B&W kinescopes made from Pal colour video could be processed electronically to recover the
color information and restore the program to full colour.

This is only possible because both the PAL video system and the kinescope camera operate at 25 frames per second. Thus each frame of the resulting B&W film includes all of the video frames and fields, and more importantly the 8 field PAL colour sequence which is the key to the colour restoration process. Without the 8 field colour sequence recovery of the original colour program can not be done

In NTSC B&W kinescopes, the 4 field color sequence is lost because 12 video fields per second are not captured in the 30 to 24 frame per second conversion process thus breaking the color sequence and making recovery of the 4 field color sequence impossible.

If the original NTSC kinescope process had used a film camera operating at 30 frames per second then recovery of the 4 field color sequence would be possible and just as in the Pal kinescope method, the 30 fps NTSC kinescopes containing all the complete frames and fields, and more importantly, the 4 field color sequence could be processed to successfully recover the color signal.

Not being able to recover the 4 field color sequence from 24 frame kinescopes is the stumbling block in NTSC.