GL2 - Purple uniforms record as blue at DVinfo.net

Terry Adams · September 26th, 2003, 05:28 PM

My daugther's uniform in drill team is primarily purple. I have recorded 2 performances under different lighting and both turned out blue. One was in a gym with the camera white balance set with a white card. The other was under outdoor stadium lights. Setting that white balance didn't show purple, so I tried the other automatic white balance settings. I also tried increasing the red, but still the uniforms show as blue.
I have a UV filter to protect the lens.
Are there any other settings I can use? Is there a different filter that would help?

Barry Goyette · September 27th, 2003, 08:04 AM

Terry

From my experience in photography (and now video) I can tell you that Purple, especially deeper shades, can be very problematic on the reproduction end of things...I've found (as have others-you might do a search for purple in the gl2 forum) that the gl2 does a better job than most cameras at reproducing this particular color. My guess is that the problem has more to do with the artificial lighting that you are shooting under. Gymnasiums and sports stadiums are notorious for using light sources like metal halide, which reproduce color in very narrow wavelengths (in the case of metal halide, it nearly wipes out the red portion of the spectrum, which would cause exactly what you are seeing).

Do a test, photograph the uniform under normal daylight using either the preset daylight WB or by setting a custom one yourself. Hopefully this will show that purple is a color that your camera can reproduce. If this works then you will probably not find any solution to reproducing that color under the given light sources, short of adding a magenta filter over the lens after white balancing...which of course will make everything pink-er, not just the uniform.

If the daylight test doesn't show an improvement, then another culprit is possibly to blame...optical brighteners in fabrics can often play tricks with color reproduction...we have had issues exactly as you describe since the early 80's when these brighteners became standard items in many fabrics. A way to test this would be to compile a group of other purple items--magazine pages, paint chips, plastic items, other fabrics, ribbon...photograph them together to see if some of them appear purple, while others appear blue...

Unfortunately, if this one color is the only one that is out of whack, there is little that a filter will do (other than possibly a UV--but you've tried that). You might be able to do something in post, although I don't know of any "selective color" (as in photoshop) adjustment in any of the popular video NLE's. (I'm only really familiar with final cut pro).

One last thought, when white balanced under the lighting conditions you've described, do the rest of the colors look great, or instead maybe just a little cyan-ish and washed out in the reds. If this is the case, you might try printing a page on an inkjet printer with a 10% cyan fill. Try using this to white balance with, rather than the white card...this will shift your colors slightly red, and may just fix your problem...or maybe not. (there is a company called www.warmcards.com that makes a commercial product that will do the same thing)

Hope this is of some help.

Barry

Ken Tanaka · September 27th, 2003, 10:05 AM

Purple is, indeed, a color that video cameras of all varieties find nearly impossible to duplicate. Watch a Minnesota Vikings football game on television and you'll see that their uniforms and helmets look royal blue...even though they're very purple.

I recently read a techie article explaining why this is so, but the bottom line is: fuggettaboutit.

Ken E. Williams · September 29th, 2003, 10:34 AM

FWIW - I noticed the same purple to royal blue shift when taking stills of flowers in the garden. Perhaps this is a limitation of NTSC encoding or gamut?

I understand that there are also problems with NTSC accurately registering some shades of red.

Aaron Koolen · September 29th, 2003, 02:02 PM

Ken W, not just NTSC. I have an XM2 and I posted here about this several months ago. Someones tights in a wrestling show were purple and coming out blue. I did some a test at home and managed to get a purple flower looking purple under my home lighting so I assumed the scummy little flouro's were doing it for me.

Ken T, that's interesting to hear about pro shot stuff coming out blue too. Makes me not feel so inadequate ;)

Cheers
Aaron

September 26th, 2003, 05:28 PM	#1
Terry Adams Tourist Join Date: Sep 2003 Location: Kirkland, WA Posts: 1	GL2 - Purple uniforms record as blue My daugther's uniform in drill team is primarily purple. I have recorded 2 performances under different lighting and both turned out blue. One was in a gym with the camera white balance set with a white card. The other was under outdoor stadium lights. Setting that white balance didn't show purple, so I tried the other automatic white balance settings. I also tried increasing the red, but still the uniforms show as blue. I have a UV filter to protect the lens. Are there any other settings I can use? Is there a different filter that would help?

September 27th, 2003, 10:05 AM	#3
Ken Tanaka Retired DV Info Net Almunus Join Date: Dec 2001 Location: Chicago, IL Posts: 6,943	Purple is, indeed, a color that video cameras of all varieties find nearly impossible to duplicate. Watch a Minnesota Vikings football game on television and you'll see that their uniforms and helmets look royal blue...even though they're very purple. I recently read a techie article explaining why this is so, but the bottom line is: fuggettaboutit. __________________ Lady X Films: A lady with a boring wardrobe...and a global mission. Hey, you don't have enough stuff! Buy with confidence from our sponsors. Hand-picked as the best in the business...Really! See some of my work one frame at a time: www.KenTanaka.com

September 29th, 2003, 02:02 PM	#5
Aaron Koolen Trustee Join Date: Apr 2002 Location: Auckland, New Zealand Posts: 1,727	Ken W, not just NTSC. I have an XM2 and I posted here about this several months ago. Someones tights in a wrestling show were purple and coming out blue. I did some a test at home and managed to get a purple flower looking purple under my home lighting so I assumed the scummy little flouro's were doing it for me. Ken T, that's interesting to hear about pro shot stuff coming out blue too. Makes me not feel so inadequate ;) Cheers Aaron __________________ My Website Meat Free Media

September 27th, 2003, 08:04 AM	#2
Barry Goyette Trustee Join Date: Oct 2001 Location: San Luis Obispo CA Posts: 1,195	Terry From my experience in photography (and now video) I can tell you that Purple, especially deeper shades, can be very problematic on the reproduction end of things...I've found (as have others-you might do a search for purple in the gl2 forum) that the gl2 does a better job than most cameras at reproducing this particular color. My guess is that the problem has more to do with the artificial lighting that you are shooting under. Gymnasiums and sports stadiums are notorious for using light sources like metal halide, which reproduce color in very narrow wavelengths (in the case of metal halide, it nearly wipes out the red portion of the spectrum, which would cause exactly what you are seeing). Do a test, photograph the uniform under normal daylight using either the preset daylight WB or by setting a custom one yourself. Hopefully this will show that purple is a color that your camera can reproduce. If this works then you will probably not find any solution to reproducing that color under the given light sources, short of adding a magenta filter over the lens after white balancing...which of course will make everything pink-er, not just the uniform. If the daylight test doesn't show an improvement, then another culprit is possibly to blame...optical brighteners in fabrics can often play tricks with color reproduction...we have had issues exactly as you describe since the early 80's when these brighteners became standard items in many fabrics. A way to test this would be to compile a group of other purple items--magazine pages, paint chips, plastic items, other fabrics, ribbon...photograph them together to see if some of them appear purple, while others appear blue... Unfortunately, if this one color is the only one that is out of whack, there is little that a filter will do (other than possibly a UV--but you've tried that). You might be able to do something in post, although I don't know of any "selective color" (as in photoshop) adjustment in any of the popular video NLE's. (I'm only really familiar with final cut pro). One last thought, when white balanced under the lighting conditions you've described, do the rest of the colors look great, or instead maybe just a little cyan-ish and washed out in the reds. If this is the case, you might try printing a page on an inkjet printer with a 10% cyan fill. Try using this to white balance with, rather than the white card...this will shift your colors slightly red, and may just fix your problem...or maybe not. (there is a company called www.warmcards.com that makes a commercial product that will do the same thing) Hope this is of some help. Barry

September 29th, 2003, 10:34 AM	#4
Ken E. Williams Regular Crew Join Date: May 2003 Location: New Hampshire Posts: 55	FWIW - I noticed the same purple to royal blue shift when taking stills of flowers in the garden. Perhaps this is a limitation of NTSC encoding or gamut? I understand that there are also problems with NTSC accurately registering some shades of red.