What does the sharpening knob do?

[knn]

I have a general question about the sharpening knob of VCRs.

What does "softness" and "sharpness" mean?

When I turn the knob to the left and the video softens, is a blurring filter applied? Or is this the picture as it is?

So my question is basically:

Is it
blur (left) - unfiltrered (middle) - sharpen (right)

Or is it
normal (left) - sharpen a bit (middle) - sharpen a lot (right)

Thank you for any answer.

[kadzbiz]

Wow, what a question. My question is "why do you want to know"? I would suggest that either direction applies a filter and that the middle position is unfiltered.

[lordsmurf]

I've never seen a VCR with such a knob. And I've owned a lot of VCRs in the past 25+ years.

[edDV]

I've never seen a VCR with such a knob. And I've owned a lot of VCRs in the past 25+ years.

I had a NEC S-VHS deck with DNR that had such a control. An analog TV with a sharpening control employs a low pass filter to remove high frequencies (detail). One would use this to reduce high frequency noise. In the other direction the control would enhance high frequencies. This would sharpen edges but also amplify high frequency noise.

[davideck]

Basically, a sharpness control is a high frequency gain control for video, similar to a Treble control for audio. Higher gain at high frequencies yields a sharper picture, while a lower gain yields a softer picture.

Many VCRs have sharpness controls. The Panasonic AG-19XX VCRs have a Sharpness slider, where the center detent provides a gain of 1 (no boost or cut) and sliding it left or right decreases or increases the high frequency gain, respectively.

[Video Head]

I've never seen a VCR with such a knob. And I've owned a lot of VCRs in the past 25+ years.

I have had such a knob on a Mitsubishi and 2 different Sony VCR's. As I usually have a ProcAmp connected I would just leave it in the middle or neutral position. I found that the effect they gave was sort of an "off or on" effect. No real control...just a big blast of hard or soft. Not a real tool.

VH

[Alan69]

When I turn the knob to the left and the video softens, is a blurring filter applied? Or is this the picture as it is?

So my question is basically:

Is it
blur (left) - unfiltrered (middle) - sharpen (right)

Or is it
normal (left) - sharpen a bit (middle) - sharpen a lot (right)

Ever heard the expression 'everything's relative'? Without an independent reference for the same system, when it's set to the 'blur' end you'd have no real way tell if it's actually 'blurring it more' a little or if you're at the low end and the circuit only 'sharpens' and any blur down there is due to the rest of the circuitry. In other words no matter what you're seeing the circuit could really be set up to do either of those, positive to negative adjustment, or only positive. Is the train speeding down the track? Or is it sitting still with spinning wheels, and the rest of the world and track are rushing by under it? With only a relative measurement, you have no way to tell..

Realize that if it's hardware you're talking, even if the circuit is only additive or only subtractive, they will probably have moved the end point up or down vs that, so that the 'neutral' would be somewhere near the middle of the adjustment. Also realize that since the circuit is designed to affect the video signal, it may well do so even at its most neutral setting. Due to amplifier and component limitations, it will probably be affecting the video slightly even when you put it to where the overall average is exactly the same as the incoming signal.

It is mainly a visual function. You adjust it to where it looks best for what you want, and be happy with it. If you don't want this and only want an exact copy of the input, don't even put it through something with a 'sharpness' control, only use something that has an exactly flat amplifier or as close as possible. Pretty much same goes for software 'sharpness' as well.

Technically, you could expect a 'sharpen' control to start at neutral and only affect the signal to enhance sharpness, and a 'sharpness' control to swing both ways and have center as neutral. But most people absolutely suck in logic and especially in relating logic to language, and the person putting this label on equipment often has no idea how the circuit was designed etc etc.

[oldfart13]

Both my Sony SLV-R5UC and Hitachi S730 have sharpness controls which are best left in the center position unless you REALLY know what you are doing....