White balance at DVinfo.net

Kris Verstappen · March 9th, 2004, 04:28 AM

Hey all !

I'm a new owner of an XM-2 and so far I'm impressed. My previous camcorder was a Sony Hi8 and it was pretty old :)

I was messing around a bit with custom white balance yesterday, using a white sheet of paper. But if I understand correctly, it would be better to white balance with a 18% gray card. Somehow I don't understand how you can "white" balance with a gray card. So could someone explain this to me, or am I just wrong? :)

Robin Davies-Rollinson · March 9th, 2004, 04:46 AM

Always white balance with white! (well, there are some little tricks you can play with non-white materials, but that's not relevant here) Just make sure that it's not over-exposed when you try to balance.

Robin.

Kris Verstappen · March 9th, 2004, 04:55 AM

Thanks for your answer, Robin.

So if I get it right: gray cards are then only used for light metering. Especially in photography I suppose.

What do you people use for white balancing? Normal paper? Sheep? ;)

Jeff Donald · March 9th, 2004, 06:23 AM

A grey card contains equal parts of red, green and blue. You can WB to a grey card and many people do to avoid the over exposure problem Robin mentions. You will get color shifts if you WB to colors that do not contain equal parts of R, G, and B.

Kris Verstappen · March 9th, 2004, 08:32 AM

Ah great! Like that it does make sense. Thanks to both of you again.

Aaron Koolen · March 9th, 2004, 02:50 PM

But Jeff, aren't you still telling the camera that gray is now white, so anything looking like that grey card will come out white? And so whites will be, well, not white...or "too" white?.

Aaron

Jeff Donald · March 9th, 2004, 02:59 PM

White is only a mixture of R, G, and B, as is black. The absolute value of white is a product of exposure (aperture, shutter speed and gain). You can WB to any shade of grey, as long as the R, G and B components are of equal value.

Graham Bernard · March 10th, 2004, 01:24 AM

. .Just as an aside here . . I recently went to a WB workshop where the "lead" demonstrated the use of a Blue lighting gel placed in front of the lens while WBing to make the shot warmer & reddish . . it worked very well .. Of course I as impressed . . I think others there knew about this "trick" . . BUT, and this is my point, it really drove home to me the value of correct WBing AND where the rules could be broken, for an effective result - yeah?

Grazie

Robin Davies-Rollinson · March 10th, 2004, 01:35 AM

That's what I meant in my previous post about various little tricks....
Getting back to what type of card, I have never used or seen used a grey card for balancing. In the day job, I use - or if I'm directing, someone else is using - various cameras from dcvam, digibeta to hi-def and we all use a white card. Sometimes it's just a sheet of paper on the PA's note pad.
Any major colour grading is going to be done in post anyway!

Robin.

Graham Bernard · March 10th, 2004, 01:52 AM

. . and this is what Robin "touched-on" in the his previous post . . [ I knew I should have added this ;-) . . . ]

. . The other thing this chap mentioned was that there is no such thing as a colour camcorder . .they are all black and white . .with colour "filters" and they are R,G,B . . . that helped me too .. .

Cards and their "hue" are very important. They are important as a small swing away from the "numbers" can give large chaanges in what you record . . . I've was told by a pro that he WBed straight at a lamp! I would not do it .. . seems a bit drastic . .

Robin, I think some "numbers" are in order here . .yes? What are the numbers and values of R,G,B? Wouldn't this assist? . . This is my "hamfisted" attempt to put some science into the discussion - yeah?

Grazie

Robin Davies-Rollinson · March 10th, 2004, 02:04 AM

Take a look at this: http://www.help4web.net/webmaster/Color/RGB-Values.html
for values of "different" whites, as well as some other colours!

Robin.

Graham Bernard · March 10th, 2004, 02:13 AM

Robin! That's brilliant! And so fast too . . I'm very impressed . . . I've seen this information in various ways but never so beautifully outlined and easily viewed. . It's a real pleasure to scan through it .. thanks for sharing your knowledge . .

The one thing a immediately scanned was the examples of "white" and the numbers it is made from . .

Thanks again,

Grazie

Jeff Donald · March 10th, 2004, 06:36 AM

Those colors are only a starting point. The colors mixes they are purposing are not correct for NTSC or PAL video. The site is for web designers and RGB values can be very different from NTSC colors. The site lists black as 0, 0, 0, but for video it is 16, 16, 16.

The problem with white balancing off paper and other products is they contain optical brighteners, which contain a large blue component. The use of grey cards (18% grey used for film exposure) has been discussed extensively here in the past. Do a search on grey cards (gray) and you'll find various detailed discussions on the matter. Custom WB cards has also been discussed.

Graham Bernard · March 10th, 2004, 07:38 AM

Hmmm .. I wonder if Robin noticed this too .. I do hope so . . . interesting . . Thanks for the "warning" that this list is a starting point. Of course the other thing is that we are all "viewing" whatever colours through a whole range of decoding devices . . CRTs and LCD TFTs and goodness knows what else! . . ..

Thanks for the Heads-Up on this Jeff,

Grazie

March 9th, 2004, 04:28 AM	#1
Kris Verstappen New Boot Join Date: Nov 2003 Location: Belgium Posts: 22	White balance Hey all ! I'm a new owner of an XM-2 and so far I'm impressed. My previous camcorder was a Sony Hi8 and it was pretty old :) I was messing around a bit with custom white balance yesterday, using a white sheet of paper. But if I understand correctly, it would be better to white balance with a 18% gray card. Somehow I don't understand how you can "white" balance with a gray card. So could someone explain this to me, or am I just wrong? :)

March 9th, 2004, 06:23 AM	#4
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	A grey card contains equal parts of red, green and blue. You can WB to a grey card and many people do to avoid the over exposure problem Robin mentions. You will get color shifts if you WB to colors that do not contain equal parts of R, G, and B. __________________ Jeff Donald Carpe Diem Search DVinfo.net for quick answers \| Where to Buy? From the best in the business: DVinfo.net sponsors

March 9th, 2004, 02:50 PM	#6
Aaron Koolen Trustee Join Date: Apr 2002 Location: Auckland, New Zealand Posts: 1,727	But Jeff, aren't you still telling the camera that gray is now white, so anything looking like that grey card will come out white? And so whites will be, well, not white...or "too" white?. Aaron __________________ My Website Meat Free Media

March 9th, 2004, 02:59 PM	#7
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	White is only a mixture of R, G, and B, as is black. The absolute value of white is a product of exposure (aperture, shutter speed and gain). You can WB to any shade of grey, as long as the R, G and B components are of equal value. __________________ Jeff Donald Carpe Diem Search DVinfo.net for quick answers \| Where to Buy? From the best in the business: DVinfo.net sponsors

March 10th, 2004, 06:36 AM	#13
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	Those colors are only a starting point. The colors mixes they are purposing are not correct for NTSC or PAL video. The site is for web designers and RGB values can be very different from NTSC colors. The site lists black as 0, 0, 0, but for video it is 16, 16, 16. The problem with white balancing off paper and other products is they contain optical brighteners, which contain a large blue component. The use of grey cards (18% grey used for film exposure) has been discussed extensively here in the past. Do a search on grey cards (gray) and you'll find various detailed discussions on the matter. Custom WB cards has also been discussed. __________________ Jeff Donald Carpe Diem Search DVinfo.net for quick answers \| Where to Buy? From the best in the business: DVinfo.net sponsors

March 9th, 2004, 04:46 AM	#2
Robin Davies-Rollinson Trustee Join Date: Dec 2002 Location: Gwaelod-y-garth, Cardiff, CYMRU/WALES Posts: 1,215	Always white balance with white! (well, there are some little tricks you can play with non-white materials, but that's not relevant here) Just make sure that it's not over-exposed when you try to balance. Robin.

March 9th, 2004, 04:55 AM	#3
Kris Verstappen New Boot Join Date: Nov 2003 Location: Belgium Posts: 22	Thanks for your answer, Robin. So if I get it right: gray cards are then only used for light metering. Especially in photography I suppose. What do you people use for white balancing? Normal paper? Sheep? ;)

March 9th, 2004, 08:32 AM	#5
Kris Verstappen New Boot Join Date: Nov 2003 Location: Belgium Posts: 22	Ah great! Like that it does make sense. Thanks to both of you again.

March 10th, 2004, 01:24 AM	#8
Graham Bernard Old Boot Join Date: Aug 2002 Location: London UK Posts: 3,633	. .Just as an aside here . . I recently went to a WB workshop where the "lead" demonstrated the use of a Blue lighting gel placed in front of the lens while WBing to make the shot warmer & reddish . . it worked very well .. Of course I as impressed . . I think others there knew about this "trick" . . BUT, and this is my point, it really drove home to me the value of correct WBing AND where the rules could be broken, for an effective result - yeah? Grazie

March 10th, 2004, 01:35 AM	#9
Robin Davies-Rollinson Trustee Join Date: Dec 2002 Location: Gwaelod-y-garth, Cardiff, CYMRU/WALES Posts: 1,215	That's what I meant in my previous post about various little tricks.... Getting back to what type of card, I have never used or seen used a grey card for balancing. In the day job, I use - or if I'm directing, someone else is using - various cameras from dcvam, digibeta to hi-def and we all use a white card. Sometimes it's just a sheet of paper on the PA's note pad. Any major colour grading is going to be done in post anyway! Robin.

March 10th, 2004, 01:52 AM	#10
Graham Bernard Old Boot Join Date: Aug 2002 Location: London UK Posts: 3,633	. . and this is what Robin "touched-on" in the his previous post . . [ I knew I should have added this ;-) . . . ] . . The other thing this chap mentioned was that there is no such thing as a colour camcorder . .they are all black and white . .with colour "filters" and they are R,G,B . . . that helped me too .. . Cards and their "hue" are very important. They are important as a small swing away from the "numbers" can give large chaanges in what you record . . . I've was told by a pro that he WBed straight at a lamp! I would not do it .. . seems a bit drastic . . Robin, I think some "numbers" are in order here . .yes? What are the numbers and values of R,G,B? Wouldn't this assist? . . This is my "hamfisted" attempt to put some science into the discussion - yeah? Grazie

March 10th, 2004, 02:04 AM	#11
Robin Davies-Rollinson Trustee Join Date: Dec 2002 Location: Gwaelod-y-garth, Cardiff, CYMRU/WALES Posts: 1,215	Take a look at this: http://www.help4web.net/webmaster/Color/RGB-Values.html for values of "different" whites, as well as some other colours! Robin.

March 10th, 2004, 02:13 AM	#12
Graham Bernard Old Boot Join Date: Aug 2002 Location: London UK Posts: 3,633	Robin! That's brilliant! And so fast too . . I'm very impressed . . . I've seen this information in various ways but never so beautifully outlined and easily viewed. . It's a real pleasure to scan through it .. thanks for sharing your knowledge . . The one thing a immediately scanned was the examples of "white" and the numbers it is made from . . Thanks again, Grazie

March 10th, 2004, 07:38 AM	#14
Graham Bernard Old Boot Join Date: Aug 2002 Location: London UK Posts: 3,633	Hmmm .. I wonder if Robin noticed this too .. I do hope so . . . interesting . . Thanks for the "warning" that this list is a starting point. Of course the other thing is that we are all "viewing" whatever colours through a whole range of decoding devices . . CRTs and LCD TFTs and goodness knows what else! . . .. Thanks for the Heads-Up on this Jeff, Grazie