Video proc amp settings for VHS capture with ATI 600 USB?
 

I've just started archiving my VHS tapes and I noticed the picture is way too dark with the default "video proc amp" settings.

I need advice on how should I go about about changing these setting. Do I just do it by eye or is there a more precise way?

Also what exactly does the "VCR input" check box do?

Several ATI 600 users have reported that the checkbox refers to DirectShow settings that are not implemented for the ATi 600 and a couple of other capture devices. So, for the ATI 600 at least, the checkbox settings do nothing.

bUsually, only the brightness and contrast filters are useful. Most ATI 600 users turn sharpening down. Brightness adjusts black levels. Contrast adjusts the bright end. Hue and Saturation seldom come into play with analog tape's frequent color balance changes--better to adjust that in post processing. The saturation control on most capture devices has a serious limitation -- it adjusts saturation for all colors at once, not just one maverick color. You'll have to experiment with the sat control to see what works, if you use it at all. Good color correction of analog tape during capture is usually painful and futile, as you'll soon see, and often can be undone only by recapturing.

VirtualDub's capture histogram measures luminance input levels and works only in Preview mode. Use VDub capture's "Cropping" window to mask off black borders and bottom head switching noise that can throw off the histogram readings. Just as in the YUV histogram posted in your sample image, the "safe" y=16-235 range is bordered by unsafe shaded areas on each side that turn red when data overflows the 16-235 range. Values that spill into the red area indicate clipping, and will be further clipped by RGB editors and display devices. The histogram you posted shows black clipping.

After making proc amp adjustments and checking with the histogram, restore all cropping parameters to zero to turn off cropping, and turn off the histogram.

Trying to judge clipping areas by eyeball is very inaccurate and gets pretty wacky when using an uncalibrated monitor.