Modern monitors, but a new feature? Horizontal 'Clock' adjustment?

[save2600]

Warning - this may be a really dumb question (this setting is NOT to be confused with a horizontal picture adjustment). But...

I know this topic has been beaten to death, especially by those living in the U.S., but looking around lately - I have seen a new adjustment called 'Clock'. In stores, the median setting is around 50. Pressing it to the left and watching it count down, even beyond 15, the entire screen shifts incrementally the left AND scrunches the image a bit.

You may then centre the image by adjust the horizontal placement. Looking at the specs of these newer monitors online (samsung, AOC and LG all have this new to me feature), they claim that the horizontal sync rate is 30khz. Well, I did manage to find a model that goes as low as 25khz, but still not 15khz.

SO... has anyone else noticed this "clock adjustment" yet? Are you REALLY adjusting the clock rate of the horizontal sync?!?

Inquiring minds want to know...

[Zac67]

It's not the horizontal line frequency, it's about the pixel clock.

TFT monitors are digital displays - they've got to resample the analogue VGA/RGB input. While resampling you'll only get a 100% sharp display when each sampled pixel matches exactly one output pixel: the sample frequency and the phase have to match - the better they do, the less sharpness you lose.

Clock Adjustment is simply the sample frequency/pixel clock; it it's too low you lose horizontal pixels and the image looks squashed. If it's too high you get doubly sampled/bogus pixels and the image gets stretched.

[save2600]

Thanks Zac - that makes sense to me and would also explain why LCD monitors look like crap when using their analogue inputs huh?

[Zac67]

Yes, that and the usual 'not quite' 24 bit color depth which may amplify noise quite a bit (low brightness background swimming and such).