white or gray balanced on digital camera

[william lan]

I am quite confused of the white balance on video camera. Normally white paper is used to execute the white balance but why Gray card can be used too? Does this mean that the gray colour will be neutralised to 'white' since a white paper with colour tint will have the colour tint neutralised during 'white balance'? Please help explain in details. Thank you very much.
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[David Rasberry]

White balance should be done ideally with a color neutral calibrated reference, white or gray doesn't matter. A Kodak 18% gray reference card is as good as any.
Random pieces of white paper may have subtle color casts that can throw the balance off slightly.

 

[Liam Hall]

Gray is just underexposed white.

 

[David Mullen ASC]

And white is just overexposed grey.

 

[George Butterfield]

If you use a white sheet you will get a setting, if you use an 18% grey card you will get a different reading. I don't know which one you should use with a RED camera to get an accurate white balance. Maybe Grahame will explain this once and for all. Of course you can always do tests for your unique 'setup'.

 

[Phil Holland]

You can use grey or white. I don't think there's anything wrong either way. But, I'll share my experience with this insanity.

I prefer to use an 18% grey card for the majority of white balance adjustments/readings. Mostly due to white cards picking up too much reflected light. If the scene has a lot of ambient object color contamination I've found white to be a bit inaccurate on numerous types of materials. I am often angling my grey card towards the key light or grabbing a specific shot at a better angle for color reference.

I tend to slap a white and grey card on the back of my slate and flip it just before a take so I have the option for both when color correcting later.

While I do prefer grey, I'll give you an example where white was very useful recently. I was shooting an interior with one key, one fill, and ambient daylight fill through windows and a screen door. I noticed that the sun bounced off the aged stucco wall and was producing a greenish yellow light. You could see this by rotating the white card towards my balanced K5500 key light. Added a bit of filtration to the key and fill and to get a bit more green in there. When color correcting in post I balanced to the bounced light off the wall. Adding some color to the lights and paying attention to color cast in the reflected daylight solved a potentially hazardous skin tone and color cast issue later on.

Beyond white balance, it is useful to have a white and grey reference for exposure and metering purposes, especially when lighting for close ups and tighter shots. For precision work though I use a full color card. I keep a Passport Color Checker on me pretty much at all times. Handy little bugger. Rugged too.

I'm pretty darn sure this is my most photographed subject.

 

[william lan]

Forgive me going back to basic. When white balance on a piece of white paper tinted with orange or whatever colour ambiance, we neutralise the ambiance turning the tinted white paper to pure white. Thus white balance on gray card with neutralise gray to white too. If so, anything with that grade of gray on the object will be captured as 'white'. Does this sound right? Really need any expert explanation. Sorry for the ignorance.

 

[David Rasberry]

fi you white balance on an off white paper, the paper will look neutral white afterwards, but all other color values in the scene will be shifted in the opposite direction, warm white paper will result in cooler scene colors, cool white paper in warmer scene colors.
I have used this trick deliberately to shift color balance slightly on video cameras where you don't have fine control over the color balance after the footage is recorded.

 

[william lan]

fi you white balance on an off white paper, the paper will look neutral white afterwards, but all other color values in the scene will be shifted in the opposite direction, warm white paper will result in cooler scene colors, cool white paper in warmer scene colors.
I have used this trick deliberately to shift color balance slightly on video cameras where you don't have fine control over the color balance after the footage is recorded.

Yes I agree with warm white paper will result in cooler scene colours and vice versa. Do you mean 'off white' is within the region of 'gray' irrespective of %? I presume this is because warm white paper is 'bleached' to white after throwing away the warmth and the cool white paper is 'bleached' to white after throwing away the coolness. So, will the gray paper be 'bleached' to white after throwing away the 'gray'?

 

[william lan]

please post your opinion, I need this urgently. Thanks.

 

[Erik Bien]

So, will the gray paper be 'bleached' to white after throwing away the 'gray'?

When you white balance a video camera you're only adjusting the color, not the exposure. So, if you balance to a gray card, the camera should record the card as a "neutral" (in other words, neither "warm" nor "cool") gray.

 

[Eric Lagerlof]

Additive color 'creates/registers' white as 3 equal amounts of red, green and blue light. When you white balance a camera, your telling whatever your camera is pointing at to adjust its internal RGB output levels to be equal so you are recording/seeing white- regardless of what actual color the card might be. In the 'real' world this is used to compensate for variations in color temperature, a white card at a beach at sunset is going to be a different white than that same card under fluorescent lights in an office setting. Our eyes/brains compensate, a white card is a white card... Video cameras are not so smart.

A camera looking at a grey card will do the same thing, adjust its proc amps so that the RGB levels are equal, resulting in an effective wite balance.

That should do you for now...black balance later

 

[Graeme Nattress]

On the RED, white balance doesn't effect the RAW data that is recorded.
White balance can be set on white or grey - it matters not as long as the white or grey is neutral. The result is that white becomes neutral white or the grey becomes neutral grey.
What is important is: not too dark, neutral colour, not clipping. White can be clipping as it's bright, which is why grey is often preferred. But as long as white is not clipping that is fine.

Graeme