the 24 frames of film across 60 interlaced fields. This maintains the runtime of the film and preserves the original audio, but may cause worse interlacing artefacts during fast motion. NTSC receivers have a tint control to perform colour correction manually. If this is not adjusted correctly, the colours may be faulty. The PAL standard automatically cancels hue errors by phase reversal, so a tint control is unnecessary yet Saturation control can be more useful. Chrominance phase errors in the PAL system are cancelled out using a 1H delay line resulting in lower saturation, which is much less noticeable to the eye than NTSC hue errors. However, the alternation of colour information—Hanover bars—can lead to picture grain on pictures with extreme phase errors even in PAL systems, if decoder circuits are misaligned or use the simplified decoders of early designs (typically to overcome royalty restrictions). This effect will usually be observed when the transmission path is poor, typically in built up areas or where the terrain is unfavourable. The effect is more noticeable on UHF than VHF signals as VHF signals tend to be more robust. In most cases such extreme phase shifts do not occur. PAL and NTSC have slightly divergent colour spaces, but the colour decoder differences here are ignored. Outside of film and TV broadcasts, the differences between the two formats when displaying video games are quite dramatic. Games ported to PAL have historically been known for having game speed and frame rates inferior to their NTSC counterparts, being typically slowed by approximately 16.7% in order to avoid timing problems or unfeasible code changes. Full motion video rendered and encoded at 30 frames per second by the Japanese/US (NTSC) developers was often down-sampled to 25 frames per second or considered to be 50 frames per second video for PAL release—usually by means of 3:2 pull-down, resulting in motion judder. In addition to this, PAL's increased resolution was not utilised during conversion, creating a pseudo letterbox effect with borders top and bottom, which looks similar to a 14:9 letterbox, and leaving the graphics with a slightly squashed look due to an incorrect aspect ratio caused by the borders. This was especially prevalent during the 8-bit and 16-bit generations when 2D graphics were used almost exclusively. The gameplay of many games with an emphasis on speed, such as the original Sonic the Hedgehog for the Sega Genesis/Mega Drive, suffered