Use of Grey Card: simple approach

[Asher Kelman]

Use WhiBal or Grey Card: simple approach

Let me start this off by giving ther advantages.

Let's say you are photographing in mixed light, you can take a shot which includes a grey card or a Whi-bal card or other standard and by merely clicking on the grey with the eye dropper with the eye dropper in any one of a number of software packages, the contaminating hues are removed.

My impression is that if you now don't alter your color setting in any software, then if you now print that file with an Epson printer with the supplied profile being used a separate thereas) you will get a darn good print, even though the screen picture may not be perfect.

This thread is just for instructions in different software packages for using the WhiBal Grey card or similar.

Asher

 

[Bart_van_der_Wolf]

Let me start htis off by giving ther advantage.

Let's ay you are photographing in mixed light, you can take a shot which includes a grey card or a Whi-bal card or other standard and by merely clicking on the grey with the eye dropper with the eye dropper in any one of a number of software packages, the contaminating hues are removed.

Yes, it is very difficult (if not impossible) to determine if an unknown object is e.g. red and illuminated with a kind of daylight illumination, or white and illuminated with a reddish kind of illumination. Some objects make it easier to approximately guess the correct color (as we remember it), but nothing beats a known reference that allows to 'neutralize' the scene's color balance with a single click (works best with Raw files).

That doesn't mean that a slight color cast won't benefit the look of an image, but a neutral gray/grey card or a white reference does offer a great starting point. Creativity can take over from there ...

Bart

 

[Asher Kelman]

..... but a neutral gray/grey card or a white reference does offer a great starting point. Creativity can take over from there ...

Bart

\
O.K. Now I'm trying to get us going to make this entry forum work. The idea is to get someone up and running and then be able to wade in to the main forums. So everything should be simple, workable, concise and well written.

Now let's have your simplest steps to use that for for an entry level digital photographer (Mary or a film guy with his first DSLR).

Use whatever software you can describe best.

Asher


You can include advanced variations and considerations in the Color Management thread and link to it as "for more advanced discussion, see here")

 

[Dierk Haasis]

Let's ay you are photographing in mixed light

Bad example, a grey card reference may help you with mixed lighting conditions but usually you won't get a good result. Although I consider it quite clear why, a short explanation:

Say you have two different coloured lights shining on you WhiBal, one red, the other blue. One side of your card shows blue, the other red and there'll be a continuous change from one to the other giving several purplish hues in between. Wherever you now click to get a neutral grey you will end up with a huge colour shift in some areas towards neutral, one huge shift towards the complementary cast [complementary to the colour you clicked on] and minor shifts in between.

The main use of a neutral grey card is in everyday shooting situations under one dominant light, where you get one or several reference points throughout a series of photos giving you a one-click possibility to the correct colour. I usually shoot one in sunlight, one in a light shadow [don't ever use the dark shadows not brightened by scattered light] and probably one of each with flash.

Be aware that a neutral reference is death to any special effect shot based upon light: night shots, sunsets/-rises, mixed lighting for coloured backgrounds etc.!

 

[Asher Kelman]

Dierk,

Your answer has validity, but not in this section except to say,

just for here, as an entry suggestion, gray card is fine in most lights where one light is dominant such as in a social event or outside during the day.

That is the working assumption for this thread since this is entry level.

More advanced comment on the trials and tribulations of wonderful sunsets etc and how to ruin them, belongs in the http://www.openphotographyforums.com/forums/showthread.php?t=927 This thread is very interesting and reflects some of your thoughts.

What we want to do is leave that out for the moment.

Just a workflow for using a grey card for remove unwanted casts with CS2, Lightzone or whatever you know how to demonstrate.

Then we can refer to this simple thread the next time someone asks!


Thanks,

Asher

 

[Dave New]

The first correction I would make is not to refer to a 'gray card', lest the entry level digital photographer make the mistake of using one.

The so-called gray cards were not designed for color-balance, but for exposure-setting. Recommended instead something like the 'WhiBal' or a GretagMacbeth color- or mini-color checker.

At least those actually have a proper gray color on them, unlike the old gray cards, which were anything but neutral.

 

[Asher Kelman]

Yes, Dave!

A great correction. I personally use WhiBal for all my work.

It is a lifesaver in indoor events especially.

Asher

 

[John Sheehy]

At least those actually have a proper gray color on them, unlike the old gray cards, which were anything but neutral.

The Kodak grey step cards tend to be magenta-ish, as well. I wish I had something like them in Color-checker material (the kodaks are far too glossy, as well).

 

[Kathy Rappaport]

Maybe I can simply this?

Okay - For example, I am doing my first professional product shoot. My subject is eyeglasses for a web page. I am using a white seamless shooting tent so the glasses will appear with an invisble background. My camera records the background as grey. How can I use a Grey card to make the background white? What steps should I take to make the background white/white?

 

[Dierk Haasis]

That's an easy one, you won't need a grey card for that: Simply dial in exposure correction; +2 may be enough but with digital you can just try it out step by step and look at the result instantly. This works great with weighted average but I also get good results with matrix.

The problem with grey cards here would be that digital cameras do not use the same 18% reflection value.

Background: Any meter has to be calibrated to a reference. For historical reasons that had been set to 18% reflection (which isn't exactly right either), a rather dark scene. The moment your subject differes greatly from this reference your meter will dial in correction, which you have to dial out again. Typical scenes are snow in the sun or black cats in a shadowy corner. The last example shows that you may have to dial in your own corrections even if the entire scene would be 18% reflective but your main subject (the black cat) isn't. Matrix [Nikon's term] did away with a lot of guess work but still isn't perfect.

 

[Bev Sampson]

Okay - For example, I am doing my first professional product shoot. My subject is eyeglasses for a web page. I am using a white seamless shooting tent so the glasses will appear with an invisble background. My camera records the background as grey. How can I use a Grey card to make the background white? What steps should I take to make the background white/white?

To my mind the background is grey because of light falloff. Perhaps you need to add more lighting or rearrange your lights to cover the background more fully. Or you could make the adjustment to a white background in Photoshop using various tools.

Bev

 

[Michael Tapes]

There are 2 issues here.

1 - Exposure. This will determine of the White back ground will appear as white or gray.

2 - White balance. This will take care of any color cast on the background and/or product.

For exposure, follow Dierk's suggestions.

For WB place a WhiBal at the product position and take a "reference shot". Setting of white balance does not matter on camera (we are assuming shooting RAW here).

Assuming PS CS2...

In Bridge, select all of the final shots along with the reference shot. Open all in Camera RAW. Select the reference shot and use the WB tool to click on the WhiBal card. Make any other tweaks in terms of exposure etc. Now click on Select all, and then Synchronize. All the shots will now be adjusted perfectly in terms of WB and exposure. Of course this assumes that the capture exposure was the same on all. If not any individual shots or groups of shots can be further tweaked.

I think it would be educational to take a look at the new WhiBal Videos at my site.

 

[Asher Kelman]

Michael,

I appreciate when the MFR of a product is available to explain things directly in a simple way, yet fit it in to other advice already given (here Dierk's).

Chuck from Canon is also here regulaly and we have a number of other "embedded" members who are key in "certain other major things" we use. We'll try to further increase this strength of OPF.

Again, Michael good to see you!

Asher

 

[Michael Tapes]

While it certainly has product bias to WhiBal, my new video tutorials will provide a good education about White Balance and the use of "Gray cards" in general.

WhiBal Video Tutorials

 

[Ray West]

Michael,

I reckon you should show the last one first - re the chess board - sells itself, then.

Best wishes,

Ray

 

[Diane Fields]

That's an easy one, you won't need a grey card for that: Simply dial in exposure correction; +2 may be enough but with digital you can just try it out step by step and look at the result instantly. This works great with weighted average but I also get good results with matrix.

The problem with grey cards here would be that digital cameras do not use the same 18% reflection value.

Background: Any meter has to be calibrated to a reference. For historical reasons that had been set to 18% reflection (which isn't exactly right either), a rather dark scene. The moment your subject differes greatly from this reference your meter will dial in correction, which you have to dial out again. Typical scenes are snow in the sun or black cats in a shadowy corner. The last example shows that you may have to dial in your own corrections even if the entire scene would be 18% reflective but your main subject (the black cat) isn't. Matrix [Nikon's term] did away with a lot of guess work but still isn't perfect.

Dierk is right on this. I do catalog shots for a pillow designer and shoot against a white background in my small studio. Its actually become sort of pieced together as its been rolled up and down, but---its still white and to have it record white, I must do a +EC. (In the end, I drop out the background and replace with a gradient of my creation plus text)

However, for correct WB (both here and in my room shots for upholstered furniture mfg.) I use a WhiBal. I place this in the first shot propped up so that it is in the same light and shoot--remove it and go on to take my regular shots. I shoot in RAW---so that in my RC (raw converter) I then just use the eyedropper (I think all of the RCs have this--can't think of any available for PCs that don't) to click on the WhiBal in the first shot and use that as reference for all my remaining shots in that series/same lighting. In most all of the RCs you can copy the WB and then paste it to the others selected--or in ACR's case, you can 'sync' the WB (and other settings) to the selected files.

For my room shots, they are in mixed lighting with color castes from old halogens in some cases, sometimes some natural light and tungsten plus my multiple flashes and using the WhiBal just saves me so many headaches since its absolutely crucial to have the fabrics be the correct colors. Not to push a particular product, but before WhiBals I used an old Kodak 'grey' card--but, as said, its not really neutral. I had tried a variety of white things, all with castes, so the WhiBal is just 'the ticket' IMO. Thanks Michael for developing it (mine is an old one, BTW, but works fine--the new ones have more bells and whistles I think, but I wouldn't trade my WhiBal for anything LOL--it saves me a LOT of work).

Hope this is helpful.

Diane

 

[Asher Kelman]

I concur with Diane. I have fussy models who want their clothes to look perfect and I shoot works of art for museums and these have to be spot on too. I have come to rely on the WhiBal for all my work.

The best thing is to be able to have girls in the pool with floating fabrics and have them hold a WhiBal and not worry about it getting wet or a splash of chorinated water. I just wash it off and dry it and its perefect. Try that with card!

So can someone give a couple of screenshots of the eye droppers to use the grey target? We want to show how easy it is.

Asher

 

[Jeff O'Neil]

Already this has been an informative thread.

I have in the past few days looked at the WhiBal tutorials and was wondering how many shooters actually use it? I have my answer.

I'll be ordering this soon as this is something that has most definetly been missing from my workflow.

Jeff

 

[Michael Tapes]

So can someone give a couple of screenshots of the eye droppers to use the grey target? We want to show how easy it is.

Asher

It is all in the videos.

 

[Ray West]

Speaking simply/roughly, are you sort of saying that a grey or white card in the 'artificial' light takes on the same colour tinge as the other objects? If you then move the grey point to where it would be under some other 'normal' light, what happens to the rest of the colours in the image? Do the colours shift proportionally, or en-masse. i.e. grey card sitting at say 190, 205,190, but should be at 190,190,190, do all shades of yellow lose 15, so brightest becomes 240 (assuming 8 bit cs) or does yellow maximum, say, at 255 stay there, but gradually other lesser shades get shifted?

Is it possible to 'catch it out' i.e. you have a shade, maybe a different surface, reflective, whatever, that is actually at or near 190,205,190. (I'm thinking here of extreme case such as in predominant sox lighting, where yellow and white look the same) that would presumably go to 190,190,190, too, unless you were aware of it.

Best wishes,

Ray

 

[Michael Tapes]

When the RAW converter (on a PC, Mac or in the camera) crete the color mapping for a shot, it NEEDS to know the color of the light. It takes this from the WB setting and uses it when mapping the color from the monochromatic 1 channel RAW data and turning it into a color 3 channel RGB image. An accurate White balance is the best path to proper color relationships and no color casts. If you want to adjust it from there, that is fine.

With inaccurate or missing WB info, it is like cooking a delicate recipe in an oven wehre the temp of the oven in unknown.

 

[Bart_van_der_Wolf]

Speaking simply/roughly, are you sort of saying that a grey or white card in the 'artificial' light takes on the same colour tinge as the other objects?

Sort of. Actually, a gray/white target ideally provides for a uniform (equal for all spectral colors) reflection of incident lighting (dominant light source + ambient lighting (mixture of lighting and local reflections)). There are algorithms (e.g. Robertson's) that allow to estimate the dominant color temperature as if the subject were illuminated by a simple black body radiator, characterized by a single color temperature.

If you then move the grey point to where it would be under some other 'normal' light, what happens to the rest of the colours in the image? Do the colours shift proportionally, or en-masse. i.e. grey card sitting at say 190, 205,190, but should be at 190,190,190, do all shades of yellow lose 15, so brightest becomes 240 (assuming 8 bit cs) or does yellow maximum, say, at 255 stay there, but gradually other lesser shades get shifted?

Unfortunately it is a non-linear (Raw) conversion, compared to the gamma adjusted color space in which we view the image. The resulting effect of white-balance clicking is therefore harder to describe than mere shifting shades, but 'all' colors will indeed shift as if the entire image is illuminated by a different 'color temperature' of light.

Bart

 

[Ray West]

I've just spent some time playing around with an IT8 colour chart, and various coloured light sources, and the eyedropper in cs2 and the whitebalance correction in bridge. It tends to raise more questions than answer. If I could be bothered, I suppose I should set up a proper test rig, with more controlled conditions, but the counter argument is that in the real world, little is naturally controlled. I am fully aware of reflections, glare, uneven lighting, flourescence, sensor noise, and the like, all or any of which effected the results I achieved. I may, try and summarise it all, quite a few numbers and images, but it may persuade someone else, perhaps with access to some more appropiate tools, to write the definitive article on 'white balance' ;-)

Ayway, this has strayed from the simple approach, and nobody has posted the two images to show how easy it is.

Best wishes,

Ray

 

[Cem_Usakligil]

Last week, I have placed an order for a WhiBal G6 Pocket edition, to be shipped to Holland by regular post. The order confirmation mentioned that I should get it within two weeks. To my pleasant surprise, it was in my snail-mail box three days later. I am very satisfied with the speed of the delivery and the product so far, thank Michael .

As soon as I have had some chance playing with it, I'll try to share my experience as a novice with you here on the forum.

Cheers,

Cem

 

[Tim Smith]

Very interesting thread. In some ways, it represents the considerable learning curve required of photographers like myself who are just entering the digital realm from a film background. In the old days it was color temperature (for color film) but now, white balance has become as integral as the more standard exposure fundamentals like film speed, shutter speed and aperture.

Thanks to everyone here who's already reached a high level of understanding, you've helped me crawl a bit closer to that understanding myself.

And by way of offering a something to the discussion, I'll reference an article by Thom Hogan concerning 18% grey cards and a bit of their history: Meters Don't See 18% Gray

Cheers!
Tim

 

[nyschulte]

Hi,

I discovered the hard way, how the proper usage of a white balance card can make life easier:

When i did a session in studio i wanted to experiment with gold reflector in a softbox.
Before i was only using the silver inlay on the softbox.

I am using a NikonD200 and shoot only RAW.

As before with the strobes, i used camera with auto white balance and change to daylight whibal in the workflow.
I was in for a bad surprise, as all shoots had a yellow (golden) cast.

After some reading, i ordered a white balance card, and took one picture with the same lighting conditions and the white balance card as subject (1 week after the orignal session).

My workflow now is the following:
I use Lightroom beta4.1 on Mac
In the development module, i choose the picture containing the whibal card.
I use the white balance selector tool on the whibal card. This will adjust white balance on this picture.
Back to the library module , i use the copy settings button. Here i select only white balance.
Then i select all pictures with the same lighting conditions and hit the paste button.

As shot

Daylight white balance

After paste settings from white balance card

Some other pictures can be seen here

PS: I ordered the whibal card after visiting Frank Doorhof's site. (DynaTech link)

This is new for me as well and the result kind of saved my day

Nicolas

 

[Mr.Lauren MacIntosh]

with regard to the following sentence: [ Just a workflow for using a grey card for remove unwanted casts with CS2, Lightzone or whatever you know how to demonstrate. ] there are so many types foto image soft ware but every time I turn around everybody states CS-2 well a lot of us are not that rich for CS-2 , I am have-ing a hard enough time with the Simple Photoshop 4 elements and now they bring out #5 ? can not win in this digital world[ Grr]

 

[John Maio]

One little point that is inferred, but not overly stressed, is that the reference card (WhiteBal, ColorChecker, etc.) needs to be in the same lighting environment as the subject. I've seen some photographers hold the card in front of a tripod-mounted camera because it was convenient, but the card wasn't in the same lighting as the subject. If your subject is human, have them hold the card in the same plane as their face. If your dog is very well trained, he can do the same.

I know everyone knows this, but I thought I'd mention it just in case...


PS: It is not necessary to focus on the card. In fact, put your lens on manual focus, or you might not get the shutter to release. Just don't forget to put it back to AF, once you have the reference image and the WB set.

 

[Mr.Lauren MacIntosh]

After Watching the tapes provided by Michael Tapes Its Interesting to veiw and think about?
As I believe he states If you can not take a reading before you shoot of your subject such as a candid foto, your take the shoot and then go to where the subject was and shoot the WhiBal card at that time ?
Hope-fully its a short time and the light has not changed that much since you shot the foto, But it does open some posiblities and may cause some
other problems :

Lets assume I am shooting a foto Of a Flower like I like to do Outside, so I put the [WhiBal] card in the area of the flower I am about to shot!
Now we now have to make a decision as to weather a high contrast foto is wanted or a soft looking foto ,you have a bunch of varie ables , this is where we have choices to make to get the foto we see in our mind and wish to present to the viewer!

So do we take a reading with the card at the point of subject which is truely the way it should be done ,But you have no shade and your shooting in strong sun lite ,So Now do I take one reading in the bright sun lite and another in the shadow lite; So now I have a split reading , and now how to deal with it when you ready to print the foto and correct the color shade:

Am I confusing the subject or am I just Confused in this whole matter:

 

[Dave New]

I believe that what Lauren is asking about is the situation where there are significant areas of the subject lit by open shade vs. direct sunlight. The shaded areas will have a much higher (cooler or more blue) color temperature than the daylit areas. Thus, if you white balance using a Whibal set in direct sunlight, the shadow-lit areas will tend to turn rather bluish in comparison. A camera set to auto-balance will often 'split' the difference (plus or minus whatever its algorithm is really doing), minimizing having either overly warm highlights or cool shadows.

This is a common problem, and the usage of a Whibal is not really at fault, here. In fact, if you wish, you can get a head-start on solving the problem by snapping reference frames with the Whibal in direct sunlight, and also in the shadow-lit areas, if possible, to get two different white balance references.

Then, using color masking or similar techniques in Photoshop, you can produce essentially 'separation' layers, one for the direct sunlit-portions, and the other for the shadow-lit portions, and apply a different color balance setting to each. Note that since you can't do this in ACR directly, you will have to put up with a much-less-than perfect white balance situation. I'd much prefer to do this kind of masking and balancing during the RAW conversion, but ACR doesn't offer that kind of flexibility (yet -- Thomas, are you listening?)

Seth Resnick (or was it Ben Willmore) showed such a technique at the last Photoshop Soup2Nuts seminar, using a shot of the Taj Majal as an example. I recall it was an unusal application of one of the layers tools, using an 'option' version of one of the buttons, to produce a feathered split layer. Bruce Fraser also used such a separation technique for shadows/highlights, to selectively apply local contrast enhancement, as well.

I'll have to see if I can find my notes, or some other reference to this technique. Seems I recall that it may be outlined in one of the "Real World" Photoshop books, or similar tomes, that give all sorts of recipes for color correction problems.

Anyone else have this techique in their toolbox, and can share?