You can't, because there IS NO COLOUR on RGB, what you need to adjust is the contrast.


Yes, RGB is best (by a LONG way), S-Video next, and then composite. However, the MPEG compression used on digital TV means that you don't get any where near RGB quality anyway - so the potential improvement is greatly reduced. Often there's really very little difference between the three!.

You CAN, at least on my Panasonic, adjust saturation and colour balance as well as contrast and brightness for both RGB and Component inputs!

What type of telly ... do people see a large difference on their

CRT or LCD or Plasma or DLP tvs

as reported not much difference on my 2 year old JVC 28in 100Hz CRT

I can do this on mine, too - also a Panasonic.

I am very disappointed with the Humax RGB on my new Samsung 32". I can see a lot of shimmering type effect round objects. Using CVBS gives a more acceptable if softer picture.

I have tried different scart leads. On my previous 26" Samsung it was quite good.

SKY through HDMI is excellent.

Any advice

Shimmering round objects is what you would expect to see if you were using composite (CVBS).

Is your Samsung 32" LCD or a CRT TV. If It is LCD then this is a problem with digital scanning. Same thing applies if your CRT TV is 100Hz scanning.

Keith

It is a brand new Samsung LCD.

A couple of observations on display characteristics - technical and subjective.

The Humax (and (every?) other digital tv box) is converting a digital signal to analogue, whether via RGB, Composite (CVBS), SVideo or RF feed. The maximum dot resolution is something like 720 (horizontal) by 576 (vertical) but many broadcasts have lower values. The characteristics of the D to A circuit will set the sharpness of transitions of colour, brightness.

When played on a 'digital' display - LCD, Plasma - the analogue signal has to be mapped to the dots (pixels) on the panel. On bigger, newer screens there will be a lot more dots than in the original broadcast. The mapping to pixels will be determined by an algorithm that will try to avoid introducing visual imperfections e.g. blocks of colour and unnatural sharp edges. (Think of what zooming in on a digital photo is like when the zoom is over 100%.)

The mapping algorithm could well give rise to 'shimmering' around edges. I expect some display algorithms work better than others and may also be happier handling the output of only a subset of digital TV decoders.

On the subjective front, some people appear to like a little noise in a picture. My 91-year-old father-in-law prefers the colour and 'sharpness' of a CRT display from a VHS video recorded on long play. To my eyes, the subtlety of colour and brightness has gone and the picture is harsh. He appears to think there is more detail, mistaking the noise for picture content. Appreciation of colour, sharpness etc is very subjective and a matter of personal taste.

I am lucky enough to be able to view a variety of inputs to my 32" LCD. In order of quality (In my opinion)

1/ SKY HD. (Stunning, especially the BBC HD).
2/ SKY SD through the HDMI input. (Excellent)
3/ The internal Freeview receiver. (Very acceptable)
4/ Humax CVBS. (No longer first choice)
5/ Humax RGB. ( Uncomfortable to watch)

As a result I only use the Humax to record when the SKY HD box is otherwise in use. This is very sad because I was a big Humax fan when I had my last LCD a 26" Samsung.

Jusat a thought - probably wrong - but does your set have a sharpness control and if so have you tried turning it down to see if that "tames" the edge effects on RGB? When I was shopping for my latest LCD TV I noticed that the default sharpness setting on some models was way too high, presumably to give a good "showroom impression" of picture quality. If this is so then CVBS might be benefitting from the extra sharpening while RGB is being "overdone".

Some sets keep a different set of settings, contrast, colour etc., for each input so that each source can be optimised although I don't know if this is the case for Samsungs.
Last edited by agraham : 29-11-2006 at 15:30

What's SKY SD like thorugh CVBS and RGB?

Re 5 - why is it uncomfortable?

Talk about comparing apples and oranges.

Join us for tomorrow's instalment; fixerman tells us which is quicker - a 2CV or a Ferrari. On Friday's programme we find out if a dolphin can swim better than humans.

If I had Sky HD, I'd sell the Humax. You're comparing it to something that sells (and prices) itself on the better picture quality. Even if the Humax had a HDMI output, it still wouldn't be a fair comparison.
Last edited by TimmyRaa : 29-11-2006 at 18:28

Because of the poor quality. The picture is coarse without fine detail except with a still picture. Once there is movement the picture detail dissolves into a blur until motion ceases. Even the station identifiers have a blurred halo round the edges. It is a backward step.

Not tried that but I will just to draw a comparison. I will report back!

I have to say that these are not normal characteristics of an RGB picture. Sounds like an issue with the TV's processing circuitry.

I have just connected my humax via RGB for the first time, I would say it's comparable to the NTL RGB signal, much better than CVBS once I got used to the more colourful picture.

What make and type of telly.

it's a JVC 32inch CRT, about 5 years old, I can't remember the model.

I need to use the CVBS setting, as in RGB mode the colours aren't natural and many of the faces are Green!

This may have something to do with my STB being Scarted through my Old VCR before the signal gets to my CRT Phillips television via another Scart.

VCR's don't do RGB, so you can't feed RGB through it.

CVBS (otherwise known as 'composite video') is a terrible compromise. Basically it's a wired version of PAL, so it has to go through the decoder and it suffers all the usual limitations eg dot crawl, limited res etc.
RGB is applied directly to the video amplifiers of the TV and is a lot better. CVBS should only be chosen if your system will not handle anything else.

Why don't you connect the VCR to the VCR SCART of your STB, and the TV to the TV SCART of your STB?

It's funny you mention green faces, as I have seen that several times on my old Humax pvr8000T. The faces of the actors or presenters take on a greenish tinge, usually when the lighting levels of the set (usually outdoors) are overcast/dull. I saw this again recently on Emmerdale.

I have also seen a pinkish hue which the Humax applied to certain parts of old black and white films.

I came to the conclusion that the Humax had some problem in its circuit design, as the Thomson box displays balanced pictures.