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AJA HA5 Question -- OT

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Steve Harley
AJA HA5 Question -- OT
on Nov 4, 2009 at 2:28:22 am

Sorry about this off-topic post - but there does not seem to be a Creative Cow forum for general AJA questions.

So, here it is:

I have a AJA HA5 -- HDMI to HD-SDI Converter. I am using it to capture the screen of a standard PC by using a DVI to HDMI adapter connected to a nVidia GeForce 9800GT graphics card.

When I open a SMPTE Color Bars .tif file on the PC -- the chroma and luminance are almost perfect on my scopes. But when I view the PC's desktop -- or an application like a web browser -- the chroma and luminance levels are completely off-the-charts and in illegal territory.

I don't know the proper way to reconcile these differences. If I use the graphic card's control panel to drop the "PC desktop" levels to a legal level -- I will adversely affect real images and web video that I display and capture from this PC.

If I leave the settings calibrated for the Color Bars .tif -- I'll have to use a legalizer and clamp down on the offending signal levels in an undesirable way.

Anyone have any suggestions?

Thanks



Here's the AJA HA5:

http://www.aja.com/products/converters/converters-hd-ha5.php


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gary adcock
Re: AJA HA5 Question -- OT
on Nov 4, 2009 at 2:38:10 pm

[Steve Harley] "When I open a SMPTE Color Bars .tif file on the PC -- the chroma and luminance are almost perfect on my scopes. But when I view the PC's desktop -- or an application like a web browser -- the chroma and luminance levels are completely off-the-charts and in illegal territory. "

Tif files may or may not be in the same color space as the video signal is. Tif's are RGB, video is NOT.


Make the Bars image your desktop background and calibrate on image as you are capturing it. if the background is not correct anything that shows will not be correct either.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL


http://library.creativecow.net/articles/adcock_gary/AJAIOHD.php




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Steve Harley
Re: AJA HA5 Question -- OT
on Nov 4, 2009 at 6:11:26 pm

Hi Gary,

Thanks for your response. I think I should have been more specific.

When I display my Avid 1080 Color Bar .tif in the Windows Picture Viewer (in full-screen slide-show mode) the bars are perfect on my Black Magic Ultrascope. If I view those bars with the Windows Picture Viewer application title bar and scroll bars visible -- my luminence levels are illegal. Those PC graphic elements are the culprit.


When I view a Photoshop-converted JPG of those same bars in a browser like Firefox (which has no facility to eliminate the title bar or scroll bar (as far as I know) the same illegal issues crop up. And when I navigate to any website on the Internet -- the levels are similarly illegal.

My principle application for the AJA HA5 is to integrate web content into videos that I am cutting for specific clients. I will need to capture computer applications -- as well as websites, images and video off the Internet.

My original thought was to use the color bars as a way to determine that the output of my graphics card was in conformance with legal video levels. But the PC's desktop and application video levels do not match the color bars images.

If I use the nVidia Control Panel I have the option of selecting RGB vs. YUV dynamic range (0-255 vs. 16-235) but that has no effect. I can also selectively control brightness, contrast and saturation parameters -- but the video looks flat and dull when I do that. And, I'd rather not use the Avid legalizer to arbitrarily force the signal level into conformance.

My quandry is how to "setup" this PC's native display -- regardless of color bars -- so that I can capture computer applications, websites, images and video off the Internet -- and incorporate them into videos that I am cutting.


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