[ken_ht]

I have a 42px25u. Has anyone else noticed a remarkable difference in the black levels between the picture when input in the component vs HDMI input? I use the "split" feature and put the pictures side by side, each input has the identical video settings and the component picture has a significantly different black level - which in turn makes the colors look much deeper. It is particularly striking when the picture has a black backdrop (e.g., a night scene). The component looks truly black and the HDMI picture has almost a dark grey background.


The picture source is my PACE cable box provided by BrightHouse cable. The situation is present with both SD and HD broadcasts.


I have 25 foot component and HDMI cables (same length). And I'm using the factory video settings.


Any thoughts?

 

[Bob Pariseau]

This is not surprising. You need to separately calibrate whites/blacks/colors/sharpness for EACH combination of source device and cabling of outputs to inputs. What would be surprising is to discover that, by pure luck, the same levels happened to work for both.


Some source devices even require significantly different calibration according to the RESOLUTION you select. This really shouldn't be the case, but nevertheless, it occurs.


Apparently with your particular hardware there is a confusion between what light output level is meant when the data asks for "Black". This is easily corrected by separately calibrating for each type of cabling. There may also be a confusion as to whether signal space is left for passing "Blacker than Black" data. You can't correct for that except by not using the connection that improperly clips "Blacker than Black".


Even if neither such problem existed, the inherent differences in processing in both the source and display for the different cabling would likely require differenct calibration levels, although perhaps not so dramatic.

--Bob

 

[jrock65]

Is it DVI to HDMI? I've read that sometimes DVI to HDMI can clip blacks.

 

[Joe Murphy Jr]

Actually, it's the HDMI-to-DVI connection that has the HDMI bug because it's caused by the HDMI transmitter chip.


If you haven't calibrated the two different inputs, you need to do this before making any comparisons. If you have, then you will need to find out where in the cable box's setup menu there are options for the HDMI output. If you can find such a menu option, try the different settings to see if the black level problem can be eliminated. Here are some examples: standard/enhanced (or expanded) -- pick standard, RGB: video/PC (or computer) -- pick video.

 

[ken_ht]

Actually it is DVI-to-HDMI.


The cable box has no adjustments for picture settings, just output resolution (mine set to 1080i) and aspect ratio.


I'll try to calibrate the HDMI picture manually to see if I can get the blacks to the level I see on the component input. The component picture is quite stunning with just the factory settings. I was naively expecting the same on the HDMI input I suppose.


Thanks for the advice.

 

[mdrums]

I have not throughly tested this but while playing around with my Denon 5900 DVD player run through a BenQ 8700+ at my friends house we did not notice a HUGE differance with DVI over Component. I actually prefered the component myself. We did notice 720p looked slightly better with movment and blacks and color saturation over 1080i.

 

[ken_ht]

One issue I'm going to have with the 42px25 is that it retains the same video settings for a given mode (like standard, cinema, vivid) across all it's inputs, so I won't be able to use the same setting, like standard, for both component and HDMI.


I'll have to tweak, say cinema, for HDMI and then use, say standard, for component. A little annoying but that's life.

 

[Joe Murphy Jr]

>>>I have 25 foot component and HDMI cables (same length). Actually it is DVI-to-HDMI.

 

[ken_ht]

I have a DVI output from my PACE cable box. I have a HDMI (digital only) input on the 42px25 TV. So I use a 25' DVI-to-HDMI cable from the cable box to the TV.


Clearer now I hope?

 

[Joe Murphy Jr]

Since HDMI cables and DVI-to-HDMI cables are not the same, yes, it is clear now.

 

[ken_ht]

So now that I clarified that I'm using a DVI-to-HDMI connection, is there still any reason I would be seeing reduced black levels compared to component?

 

[Bob Pariseau]

ken_ht,

It is almost certainly just a case of your not having properly dialed in the right level settings for the digital input yet. The manufacturer's default settings in displays are almost never correct. These displays are also pretty finicky as regards such settings. The image will improve DRAMATICALLY when you get the right levels set up for whites/blacks/colors/sharpness for that combination of source device and output/input cabling. In fact if you are using the manufacturer's default settings for your component connection, the odds are you can improve THAT image as well!

--Bob

 

[Joe Murphy Jr]

I hate to say this, but the cable company could be using a DVI setup that clips blacks. It is possible the box is geared toward 0 - 255 digital PC levels vs 16 - 235 digital video levels. That would suck, but you might have to live with it.


Can you list the output options in the cable box's menu or let us know the type of box, brand and model #? There may be a download or Help section available from the manufacturer that we could browse to possibly help you figure out the problem.

 

[ken_ht]

I have a PACE HD550 cable box:
http://www.pacemicro.com/us/products...cts.asp?id=550


The manual isn't much help.


It has both component and DVI outputs (and S-video and composite) but no settings that I can find that are specific to any individual output.


I have the component output connected to the component input of the 42px25 and the DVI output of the PACE connected to the HDMI input of the TV. I put both pictures side by side ("split" mode on the TV) and the black levels are staggeringly different.


As stated above, I might be able to tweak the video settings of the TV for the HDMI input to match what I see in the component picture, I'm just surprised at the difference I see.

 

[Joe Murphy Jr]

Thanks for posting the link. You're correct, options for the DVI output and what type of output it is are not to be found in the manual or in the specs download. I sent PACE an email for you. Maybe they will be able to answer the question of digital PC levels vs digital video levels for your cable box. It may just come down to tweaking the HDMI input.


On the other hand, it does seem like a nice cable box. Much better than the POS boxes that Charter Communications provides in my area. Not that it matters, because I canceled digital cable and gave them the box back. They kind of suck as a cable company, but I'm not paying for extra receivers for satellite service (even though the previous owner left me his dish). I just flip through the channels anyway, so analog cable fits the bill.

 

[ken_ht]

Geez, thanks for going the extra mile Joe, I appreciate that. I coulda sent the email but I was checking with you gurus first.


Ken

 

[mdrums]

I just did a test on my Denon 5900 and my Huges HD Tivo Sat receiver between DVI and component shown on a new Sim2 HT 300 E-Link and then on a RCA HD receiver Hughes HD Sat receiver and a Loewe 42 HD plasma. I set up both comp and dvi inputs and calibrated them with my dig video dvd disc. Suprisingly to me component won out. Way to many issues with DVI. I have not yet seen where DVI is a better hook up yet. maybe if you use all the same brand Sat Rec, TV and DVD player DVI might work but if you use differant brands there are too many protocall problems.

 

[Joe Murphy Jr]

Ken

This is what I received from Pace support:

Joe,

> The DVI is video level based. Are you having an issue with the DVI output?

> What make and model is your HDTV?

> Regards,

> Pace Customer Support



Based on this reply, you may want to work on the calibration of your HDMI input. The Pace box is using the correct digital video standard, so there should not be any clipping of the blacks.


You may want to check any setup options with your display's HDMI input. It may be configured to expand the 16 - 235 range to 0 - 255, thus throwing away below black and above white signals. If that's the case, you should be able to change it to a different mode (standard, normal, etc) for proper display.


I'd check this last part first, just to be sure. If it's set correctly, try adjusting the display's settings on the HDMI input.

 

[ken_ht]

Hmmmm...


Well there isn't a single input adjustment that is specific to any one input. So I will have to calibrate the HDMI using one video mode (e.g., standard) and adjust the component using another video mode (e.g., cinema).

 

[Joe Murphy Jr]

That's not quite what I was talking about, but it is an option.


What I meant was this. When you select the HDMI input, is there a section that gives you any options for what type of processing occurs (some likely terms may be expanded, enhanced, normal, RGB, standard, etc)? I'm not talking about the picture memories (Dynamic, Auto, Standard, Cinema), but something in the setup of the HDMI input.