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Old March 10th, 2009, 11:26 PM   #1
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Color reproduction anomalities

I have been recording in 720p 60fps for several years now, first with the HVX-200, and for the last few months with the HPX-170. I love the cameras and the format, but have repeatedly noticed that shades of blue and purple frequently record in a different color than the original. Its still beautiful color, but the shade is wrong. This is not a white balance problem, as it occurs under many different types of lighting, and all other colors are correctly reproduced. I assume this is a weakness of the three chip colorspace used by the cameras. Anyone out there with a technical explanation ?

Apologies in advance for the mis-spelling of "anomalities".

Last edited by Mark Donnell; March 10th, 2009 at 11:29 PM. Reason: Mis-spelling
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Old March 14th, 2009, 09:37 AM   #2
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Mark,
Are you saying that the color changes from looking at the output of the camera live to playing the footage back on the same camera into the same monitor that the color changes are more than would be expected from the compression noise introduced by playing back a recording? You haven't said how much things change. There are many possible explanations but you haven't provided enough info to suggest a complete answer.
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Old March 14th, 2009, 01:55 PM   #3
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Its actually very interesting, Daniel. Again, only on some shades of blue, purple, or wine, the color seen with your eye is very different from the color seen through the camera viewfinder. The viewfinder color matches well with the color played back from the P2 card into either a monitor or a LCD HD TV, but not with the color seen by the naked eye. All other colors match excellently, and the same phenomena occurs under several different light sources. I can't believe that I am the only one who has noticed this, although yours has been the only reply. I suppose I'll have to do some controlled studies to see whether or not this phenomena is real.
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Old March 14th, 2009, 06:37 PM   #4
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Mark,
Every camera has its own color rendition based on its electronics and optics. Your eye does not have the same limitations as the camera. The camera may match what your eyes sees under some situations but often will not. It sounds like you don't like the cameras treatment of blue which is due mostly to how the camera electronics are set up and little to do with the compression afterwards. You can try playing with the Matrix to see if that helps. Not sure if this level of Panasonics have adjustable Matrixes or just preset ones. Most likely you are looking at Panasonic's best guess as to what the color response should be. People are usually more sensitive to warmer colors so they may be biasing the camera in that direction. An adjustable Matrix can play with the values of color differently than gain, gamma and pedestal adjustments. These settings can also influence the color rendition but assuming they are correct you may not want to unbalance them to deal with this issue. Many video cameras have color rendition issues which show up with specific colors. Also remember some colors do not react well under mixed light conditions. I was once on a big industrial where the pink lit screens looked closer to purple until the other lights where turned off and the camera then read them as pink. White balancing didn't help this situation. Try color correcting some of the footage and see if you come up with a preset you like as doing it in camera may not be very reliable
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Old March 14th, 2009, 09:47 PM   #5
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Mark,

The HPX170 has a drastically different - and lower noise - color response than the HVX200 (the original, not the "A" version). In fact it's is more accurate at reproducing 18% grey than the 200 could due to the newer chipset technology.

It's always important to do a white-balance using either the built-in LCD (when properly setup using PLUGE lines) or an external (properly calibrated) monitor. Your eyes may have become accustomed to the look of the 200's output but the 170 will be different.

I think you'll find that when properly setup the output from the 170 is more natural, especially with skin tones than the 200 was. (The 200A and 170 share the same chipset)
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Old March 15th, 2009, 11:56 PM   #6
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I'm definitely not complaining about the color, but it is interesting to see these differences between what the eye sees and what the camera sees with regard to certain colors. Skin tones are always excellent - this only seems to occur with some fabric colors, but the color difference can be impressive. When it occurs, it is usually with indoor lighting, often mercury vapor lamps. I'll do some tests and see if this occurs with natural light. It is only really just a curiosity - something out of the ordinary.
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Old March 19th, 2009, 09:36 PM   #7
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Mark,
Despite your curiosity I still don't get why you think your eye would see all the same color in tone and intensity as the camera or even less likely the cameras LCD would? The more you understand about color spectrum,color temperature and color saturation the more you would understand why the camera sees what it sees regardless of what your eyes see. Monitors have their own limitations as well. Some of the limitations are intrinsic to the technology and some are adjustable. You still might be able to push the camera or monitor to see or display what you see but this will not work in all kinds of light,with all colors and certainly not with all monitors. Granted we would love to have cameras and monitors which reproduced colors the same way and as well our eyes but we don't.
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