Colour - and gammaspace.

[Asgeir Helgestad]

If you edit your stills in Photoshop you might chose to use the big, nice 16-bit colourspace called Prophoto. But if you print it or send it by mail your pics will look grey and colourless , simply because the printer can’t print all the colours in that colourspace. I suppose your mail-program can’t show them either. For that reason you should down-convert your colourspace to sRGB before you deliver photos (unless you know that your customer can use ProPhoto). And that downconvert should be Perceptual – to move all colours inside the smaller sRGB colorspace - not clipping them away. (Relative Colorimetric is what you might use to convert the other way).My question is:Does it matter what colour- and gammaspace to chose when editing videoclips in Redcine-X for TV?Can you loose colours on your way if clips get converted from a big video-colourspace (Redgamma3 - what is it?? ) to a broadcast-format? I would suppose so?I just ask because too many people tell me that my clips look more grey after I got my RED Epic, using Redcine-X. How can I make sure that my colours look great all the way?

[David Rasberry]

There is no reference standard gamma curve for REC709 compliant video. Typical studio reference monitor calibrations fall in the 2.35-2.4 gamma range vs 2.2 standard for sRGB computer gaphics.

The best way to insure your footage looks right for broadcast compliant video is to use a properly calibrated HDTV monitor, not a computer monitor, when you do your final grade and encoding pass. This doesn't have to be expensive. I use a sub $400 LG 32" ISF certified consumer LCD TV which has sophisticated calibration menus for use with colorimeters. It is a true 10bit display and provides a much better reference for HD video quality via HDMI input than any sub $1k computer monitor. Purists will tell you that plasma TV's are better, and they are. But the vast majority of people are watching LCD TV's of one kind or another these days. I grade using a calibrated Expert setting and then toggle thru all of the out of the box settings the TV has to see how it holds up under the factory viewing calibrations that most people will pick from.

Graeme has referred to Redcolor and Redgamma as "REC709 friendly".

[Terry VerHaar]

David - can you point us to this monitor? What are the specific "sophisticated calibration menus" that make it usable with colorimeters? Thanks.

[Asgeir Helgestad]

Thanks David!

If Graeme says it is REC 709-friendly, I suppose it’s mostly the same colourspace in Redgamma3 as in REC 709 and CCIR 601. I agree that you need a monitor that you trust. But this case is actually not about the monitor, but the size of the colourspace. I deliver ProRes-files in HD that get crunched down to a Standard Definition IMX. It doesn’t matter if it looks nice at my computer if the transmitter of the TV-station send out a highly compressed signal with a different colourspace. It’s like when I printed a big panorama from a ProPhoto-file, graded on the best Eizo-screen, showing AdobeRGB. When I picked it up it was black and white whith 50% of the colours! The other colours had been clipped away as the lab couldn’t reproduce that space on their printer.

[Gunleik Groven]

Asgeir. If you want to prepare colors for broadcast, it is a huge advantage to monitor the signal on a broadcast monitor... :)

Fits very well with your own example...

[Steve Shaw]

For calibration info have a look at the various pages on the Light Illusion website:

www.lightillusion.com

There is a lot of info there that should help.

[Jaakko Rinne]

David - can you point us to this monitor? What are the specific "sophisticated calibration menus" that make it usable with colorimeters? Thanks.

I would assume he means it has a CMS and 10 point grayscale calibration.

[Stacey Spears]

There is no reference standard gamma curve for REC709 compliant video.

There is now, it is defined in ITU BT.1886. Its 2.4.

[David Rasberry]

David - can you point us to this monitor? What are the specific "sophisticated calibration menus" that make it usable with colorimeters? Thanks.

Most of LG's Plasma, LCD and LED models for the last two years from 32" up carry an ISFccc certification. They are all true 10 bit xycc deep color displays. Just look for the sticker or look for it on the spec sheet. Other makes and models with this sticker will have similar menus buried somewhere. The Expert mode menus include selectable color temps, selectable gamma curves, RGB drive and offset adjustments, discrete white balance correction for each of 10 IRE gray scale reference values ( don't mess with this without a colorimeter). There is also a neat built in guided setup wizard that allows a very reasonable basic user calibration by eye.

[David Rasberry]

There is now, it is defined in ITU BT.1886. Its 2.4.

Thanks Stacey, good to know.