WB test - Grey vs. White card

[dwalker]

Many are recommending a grey card to set WB but I haven't gotten accurate skin tones with this method so I decided to conduct my own test. You might be surprised at the result.

See the results here:
http://64.85.6.147/D30_wb_test.asp

[Roger_Cavanagh]

dwalker wrote:
Many are recommending a grey card to set WB but I haven't gotten accurate skin tones with this method so I decided to conduct my own test. You might be surprised at the result.

But, which is the best?

Cheers,

[Griffin]

'nuff said. :D

[dwalker]

To Roger and Griffin:

You have both missed the point!

Since "I" did the test with the modeling head, "I" can tell you with absolute certainty that the white card yeilds the most accurate colors. From the responses I've seen over at dpreview.com, I am not alone in this conclusion.

There is no subjectivity involved except in your responses. Since neither of you have anything to compare the photos to, your conclusions are flawed and are maybe based on wishful thinking. Canon recommends the white card for good reason - it is the only method that provides accurate colors with the D30.
All the posts from those individuals using Expodisks, grey cards, styrofoam cups, coffee can lids, etc. are all trying to accomplish the same thing - to get accurate color rendition. I've not seen any posts from anyone using a white card (until now) even though the D30 manual recommends this method.

It is critical to get skin tones correct if you want your customers to continue doing business with you - not what you think "looks good".

You can lead a horse to water but...

[Roger_Cavanagh]

dwalker wrote:
You have both missed the point!

I didn't miss the point, but I had no idea that "dead nuts" was supposed to be complimentary, so concluded that the WB example was incorrect in some way. Clearly, another case of separation with a common language. :)

Cheers,

[dman65]

Can anyone tell me where to purchase a white card? None of the local camera shops have even heard of one. They all have the Grey Cards, but no one has the white cards.

[dwalker]

I purchased a package called "Kodak Gray Cards" that has one 4x5 and two 8x10 cards and lists for $14.95. All cards are gray on one side and white on the other. B&H, Adorama and Amazon.com all carry this package.

Hope this helps.

[dwalker]

Roger wrote:
I didn't miss the point, but I had no idea that "dead nuts" was supposed to be complimentary, so concluded that the WB example was incorrect in some way. Clearly, another case of separation with a common language.


Sorry Roger, I shouldn't have used a colloquial phrase. That phrase has since been replaced.

Thanks for pointing that out.

[Roger_Cavanagh]

dwalker wrote:
Sorry Roger, I shouldn't have used a colloquial phrase. That phrase has since been replaced.

Thanks for pointing that out.

Good, now we've got that sorted out. :) Can I ask exactly what you did: take a close-up picture of a white card and use that in CWB in-camera, or set CWB in conversion, or what. If you've tried different methods, do they come up with the same result?

Regards,

[JCDoss]

dwalker wrote:
...Since neither of you have anything to compare the photos to, your conclusions are flawed and are maybe based on wishful thinking...

First, I don't see a whole heckofalot of difference between the gray card and white card shot. Both look fine to me (and both look MUCH better than any of the preset WBs you used!). I think that *that's* the major lesson to be learned here... use Custom WB whenever possible.

As to gray vs white, it's subjective as you said. There's no point in arguing which is more accurate since you're the only one who was present in the studio.

JCDoss

[dwalker]

JCDoss wrote:
As to gray vs white, it's subjective as you said. There's no point in arguing which is more accurate since you're the only one who was present in the studio.


What I said was that those who responded were being subjective since they did not have access to the modeling head. My tests were objective since the modeling head provides a standard that does not change. That's the entire point - to conduct a test that is repeatable with no variables. The modeling head provides that standard. Unlike real people, the modeling head's facial characteristics, color and tone do not change. The facial color of people will change depending on many factors and cannot be depended upon to be consistent from day to day.

Even if all you shoot is landscapes, you should still have some accurate starting point before doing your post processing. If your currently using a Kodak gray card and the back of it is white, why not try it? My tests can be easily repeated by anyone.

[dwalker]

Roger wrote:
Good, now we've got that sorted out. Can I ask exactly what you did: take a close-up picture of a white card and use that in CWB in-camera, or set CWB in conversion, or what. If you've tried different methods, do they come up with the same result?


I shot both the white card and the gray card (filled the entire frame) and set the CWB in camera using the apropriate frame. When converting from Breeze Browser, I left the default WB to "As shot (Preset)" which will use the proper CWB for that particular photo.

[charles beasley]

A truly neutral white card may be best if one is careful to not overexpose it. If any of the RGB values = 255, effects will probably be undesirable. This danger is why most recommend gray card.

[dwalker]

charles beasley wrote:
A truly neutral white card may be best if one is careful to not overexpose it. If any of the RGB values = 255, effects will probably be undesirable. This danger is why most recommend gray card.

Overexpose a white card? I've never heard or seen anyone make that statement. Now you'd have to work real hard to accomplish that!
If you fill the D30 frame with the white card as you are supposed to and expose according to the meter reading you will never get that situation. Instead the meter will want to render the white card as 18% gray.
There is no problem here.

[Gomez Photography]

I have used both gray card and white card method. I have found that the gray card works best. When I got my D30, I started using a white card. I was not happy with the results. I is easy to over expose a white card. I found it more difficult to over expose a gray card. I also liked using a gray card for ambient readings since the cameras metering system looks at everything as if it was 18 % gray. So I can get a correct reading and a white balance at the same time. The gray card is part of the zone system. So there should be no difference if you are using a nuteral white or 18% gray card. The trick is to use them correctly. The white cards that I was using before was reflecting other colors because of its surface. Make sure it is a matte surface. If you want to compare the two. After setting a Custom White Balance, Take a full frame photo of a McBeth Color chart. then you will all have something in hand to compare it to. If you want real results, try icorrect. It will change your life. http://www.picto.com/pictoA.html
I have used it and am very happy with the results. You can batch process with other programs that come with your icorrect.
the process I use if in the studio is this: First I take a reading. Then I set the camera to the correct Aperture & Shutter Speed also set the camera on Auto white balance. Fill the frame and take the shot. Next, I set tne custom white balance to the image I just shot of the gray card. when I use Icorrect, i take a photo of a Mcbeth color chart full frame. I use this image to create a curve setting using icorrect. I'm ready to shoot the set , but kepping the light the same. The good thing about icorrect is that you could just do all this the simple way and shoot the image and correct later. Icorrect makes good results for most any image. Good Luck
Michael

[charles beasley]

dwalker-I was referring to a situation in which an incident meter and manual exposure is being used. Properly exposed a white patch on a Macbeth Colorchecker reads LAB:L=96 or RGB=242 in Adobe 98; half a stop over and you're close to 255. Of course if you are taking a reflective reading off the white card, the meter will give a reading that will render the card around middle gray or the same if you are in E-TTL as you were and the card occupies the metering area of the viewfinder.

Kodak gray cards are notoriously inconsistent and many are a bit on the cool (blue-green) side- hence the warm skin tones you reported when a cool gray card is used for a custom white balance.

Actually the best thing to do is use the Macbeth gray patch that is closest in reflectivity to the most important tone in the scene you a photographing,if you can zoom in enough to make one of them occupy at least the circle in the viewfinder. The reason I say this is that if, for example, you use the third gray patch from the left for a custom white balance you will find that the RGB values of that patch are close (within a point or two) to equal. The other patches won't be quite as close; a couple of patches away you may have 5 or 6 points difference. So the gray balance doesn't neutralize the entire range but only a point in the range.

[dwalker]

Charles Beasley wrote:
dwalker-I was referring to a situation in which an incident meter and manual exposure is being used. Gomez Photography wrote:
I was not happy with the results. I is easy to over expose a white card. I found it more difficult to over expose a gray card.

I appears that neither one of you have used the white card correctly. The proper way to use a white card is outlined in the D30 manual. If you follow those instructions you will not overexpose the white card.

Athough a gray card used for WB may render a scene with pleasing colors it does not render correct skin tones - the white card does. And it follows that if the skin tones aren't correct, neither are the rest of the colors. As far as iCorrect Professional goes, I have it. It's a very useful tool but it still takes work to get the skin tones corrected in a photo with WB based on a gray card - not so with a white card.

The Kodak Gray cards are useful for metering, the back side of that card (white) is more useful for WB.

I will try the McBeth Color chart, but for now, the white card has solved my skin tone WB problem.

Photography is a very subject field but there still needs to be standards to work from as a starting point. As far as I am concerned the white card used for WB, if used correctly, is part of that standard.

[Gomez Photography]

I am going to try the white card agian and read the directions this time. This discussion has been a good debate to make one think more about white balance. Please keep the experiences posted.
Michael

[charles beasley]

dwalker, With all due respect, if you didn't have such a defensive attitude, you would realize that I was agreeing with you that a white card is better than a gray card, as long as it is not overexposed.
For the sake of this discussion, I went back and read the D30 instruction book on the subject and all it says is: :"Take a picture of a white subjectct as you would a normal picture."

dwalker wrote: "Overexpose a white card? I've never heard or seen anyone make that statement. Now you'd have to work real hard to accomplish that!If you fill the D30 frame with the white card as you are supposed to and expose according to the meter reading you will never get that situation. Instead the meter will want to render the white card as 18% gray.There is no problem here."

Do you ever shoot in a studio environment with studio flashes (as opposed to 550EX in E-TTL mode?) If you do so and use an incident meter, the incident meter's reading will recommend an exposure that will render a white card white, not 18% gray as you say.

I have stated that the reason you were getting warmer skin tones with the gray cards id that many gray cards are not truly neutral. You have stated that we need a standard for doing this and I am suggesting that one exists and is widely recognized and that is a Macbeth Color Checker. Indeed it is used by many to profile digital cameras.

You have chided others for being too subjective of your test. Why dont't you include a standard such as a Macbeth in each shot of your mannequin head, so we can have an objective guide by which to judge you test?

[Gomez Photography]

charles beasley wrote:
Why dont't you include a standard such as a Macbeth in each shot of your mannequin head, so we can have an objective guide by which to judge you test?
I agree There has to be a standard that we can hold in our hands,
or ship us you "head" Ha Ha. lets not get so hot about this , we are all here to help each other get the best results. Maybe we should ask the Digital god Fred Miranda.

[dwalker]

Charles Beasley wrote:
Do you ever shoot in a studio environment with studio flashes (as opposed to 550EX in E-TTL mode?) If you do so and use an incident meter, the incident meter's reading will recommend an exposure that will render a white card white, not 18% gray as you say.

If you're not willing to take the time to expose the white card correctly then you can't come to any conclusions about it's validity. This test should be a no brainer and you can conduct it yourself (make sure you use a real white card like the back side of the Kodak gray card). Just turn down the power on your studio flashes until you get a reasonable histogram without clipping on the high end. Make sure the white card fills the frame for these shots. Set the CWB and shoot some test shots. If you have a MacBeth then include it in your test shots. It couldn't take more than 5 minutes at most.

If you don't want to use a white card, then don't - it's your choice. It is working well for me.

[oops]

Wow. This is great slam-dunk action and, like most spectators, I will probably get a chair broken over my head for butting in. This is such a "high level" discussion that it really has lots of merits for all members of the forum. The content is great, timely, and fits right in with the original purpose of this forum. I really need this information so I keep following the thread but, for crying out loud dwalker, please use emoticons so you can step on people's toes without ruining their shine!:D:D:D:D

These people are very kind and helpful; they are no threat. Take a couple of deep breath's, recompose your post a couple of times, and then fire it off. I did.:):)

[dwalker]

Last month I went to CA and spent the last two weeks of December visiting with my two daughters and their families. I took all my camera gear (about 50 lbs. worth), my Sony notebook, three backgrounds, a couple of light stands with umbrellas and two 550EX's. I took hundreds of photos using both AWB and CWB using a gray card (all shot with a Canon 28-70L). I was not at all satisfied with the colors rendered in the skin tones using these two methods. Although the colors weren't terrible, they just weren't accurate. Before I returned home, I purchased the modeling head you saw in my tests, determined to find a good, repeatable way to achieve accurate color from my D30. Like a lot of you, I originally dismissed the D30 manual's call for a white card to set WB. I finally decided to try some tests when I got home. I can tell you that with the modeling head sitting next to my monitor, I am hard pressed to notice any difference in color rendition between the modeling head and viewing the image on screen (after using the white card to set WB).

I chose to share the results of my tests here in the spirit of helping others who also may not be completely satisfied with AWB, any of the other WB presets or CWB using a gray card.
I hope someone may have benefitted from my efforts. ;)

[Roger_Cavanagh]

Well, here's a poser:

http://www.robgalbraith.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=8&t=001945

In this thread over at Rob Galbraith's place, Chuck Westfall, the occasional visiting senior techie from Canon is recommending the grey card despite the manual's recommendation.

Hmmmm?

[dwalker]

Roger Cavanagh wrote:
In this thread over at Rob Galbraith's place, Chuck Westfall, the occasional visiting senior techie from Canon is recommending the grey card despite the manual's recommendation.
In that thread, Chuck did not clarify why he made that recommendation. I suspect it was simply a compromise since the gray card can also be used to determine exposure, giving you both an exposure setting and CWB in one shot. The gray card will push the color towards the red spectrum and will not be noticed for most general photography or landscapes. From my tests, the white card produces more accurate colors which is desirable for skin tones and I continue to get better results in my actual photos not just in testing. This is true for interiors, exteriors, architectural, portraits and landscapes. For now I will continue using this method until it can be shown that there are real problems with this technique.
I wonder if Chuck has actually done any tests with the white vs. gray card.:D

[Gomez Photography]

Walker,
Are you assigning a profile for your camera? If you are, did you downlaod it or create it from your own camera? Are you also using your softproof functions for photoshop 6.0? What ever works for you is fine. I still will try the whit card when I get the time. So I am not saying that one way is more correct than the other. I just know that a Color Chart from McBeth should be the standard for most since we can all have one in our presents when compairing resultss. I did a custom white balance with the gray card and then shot a frame of a Color Chart with the exact settings. I went to the lab to print it and told then to make no corrections. the print came back an exact match. I had never had this happen before, so I stopped testing any other ways to improve this cwb method.
It seems that everyone has a way to make things work for themselves other are not sure what to do. This discussion has been a good one for all to view. They will do their own tests and hopefuly post their results. As for me, my 1D just came in so I will be doing many tests soon and will let all know the results. Michael Gomez

[dwalker]

Michael Gomez wrote:
Are you assigning a profile for your camera? If you are, did you downlaod it or create it from your own camera? Are you also using your softproof functions for photoshop 6.0?
When converting from raw to tif, I left the WB "as shot" and set the in camera profile to "normal, normal, normal". In PhotoShop, I did not assign a profile to the image. Instead I am using the ICC profile provided by the manufacturer of my monitor (Mitsubishi Diamond Pro 900u) that is loaded in the "Color Management" section of the Windows "Display Properties". In this situation, there is no difference when setting the softproof to Monitor RGB since the ICC profile is already loaded. I'm not an expert at this so if you see a flaw in my setup, by all means chime in.

I started using a Kodak gray card shortly after receiving my D30 last July and after doing a little research at this forum, a few others, Don Cohen's site and Fred Miranda's site. Most were recommending a gray card and none recommended a white card (or more correctly, made no mention of the white card). I assumed that the D30 manual was making some wacky recommendation so I ignored it. I was never really satisfied with the colors in my portrait images so I decided to investigate the recommendations in the D30 manual (hence the test with the modeling head). I've profiled my Epson 1280 printer to match my monitor. The resulting prints look exactly like the modeling head when held up for a side by side comparison as does the monitor. That fact tells me that my monitor/printer are at least very close to reality. I've read dozens of posts about profiling monitors, color space, icc profiles and such but the fact that my monitor/printer/modeling head all look the same says to me that my setup may not need additional calibration. One thing I haven't done is to send the files out to a professional lab for prints. I intend to do that soon.

For many, the gray card may be close enough for all practical purposes especially when you cannot verify the results such as landscapes. In addition, it is certainly valid to enhance those images with post processing to one's liking. I wanted to see if I could come up with a way to get more accurate color rendition when I needed it. :D

[charles beasley]

I am making another reply mostly because Oops asked for more information on the subject, and I feel that if we can get past the white vs. gray card issue we can possibly help others like Oops. I've been 100% digital in the studio about 3 years now (still film at weddings.)
I don't consider myself an expert, but the following seems to be the routine agreed upon by most "experts."

dwalker wrote:"so if you see a flaw in my setup, by all means chime in."

You are using what is known as a "closed loop" workflow: "I've profiled my Epson 1280 printer to match my monitor."
This is apparently working for you at the moment. But.... "One thing I haven't done is to send the files out to a professional lab for prints. I intend to do that soon."
What if the lab's printer doesn't match your monitor?

The two biggest flaws in your setup, if you want to go beyond a closed loop workflow, are assigning the monitor profile to your images and making your printer match your monitor.

Monitors change dramatically over time so a "canned profile" is not as good as one you make yourself with a colorimeter and profiling software such as Colorvision's Spyder and Optical. This should be done about every thirty days.

There needs to be a camera profile "assigned" to the image early on in the workflow. This profile can be one you make yourself with something like Profile City's ICC DCam, or you could use one of Fred Miranda"s free ones. Then the image needs to be "converted" to a standard working space such as Adobe 98, Colormatch, Bruce RGB,etc. In these types of working spaces equal R,G,& B values of a given tone are truly neutral shades of gray (or white or black.) The same is not necessarily true with a monitor space (profile.) You can do this assigning and coverting with an action you make or with one of Pekka's or Fred's.

Finally, the printer must be profiled to tell Photoshop how it behaves;it most definitely should not be adjusted to match the monitor. In fact, when profiling the printer any user-adjustable settings such as color balance and lightness/darkness should be set to zero and left in this neutral state.

You would keep (archive) the image in the working space and when you print to the Epson (the Epson printer driver's interface is a whole 'nother can of worms) you convert to its profile, or if you send it to a lab you or they convert from your working space to their printer's profile.(Hopefully you will choose a lab that is up to speed on all this by using profiles and not making their printer match their monitor.)

[Gomez Photography]

Thank you Charles for beating me to the explanation. I cant type too well, but you stated exactly what I would say. If you are working in a closed loop and stay there I guess it would be ok for you. But when you give your images to someone on cd and the print it out where ever they go, they might get a different image than yours. A color monitor calibrator like the Spyder is about a $400-$600 item that will make a big difference in keeping colors correct. Your camera has its very own profile too. Freds profile will work close enough for a general profile, but if you want more accurate results make one from your camera. thia is where Gray Vs White really comes to play. Some professional labs can create one for you. The system and software to do this cost thousands. Most labs that are Kodak Q labs will have the sources. What you have to do is take a photo of a color McBeth chart after you preform a CWB using Gray or White card. True tests all have standards , this is why your "head" works well in your closed loop. But not for all to see. Printers also have there very own profiles. Epson has several in there install program that are placed in you color sync folder. I use a Mac. Using these are like using Freds Profile for your camera. Each printer has its very own profile too. Use Photoshops Soft Proofing System to view and color correct the image before you print, Some labs like to use the Pro Photo RGB Working space because it has the least clipping on the files during conversions. Most labs or press companies will provide you with their printers profiles if you ask or will have them on their web site. The important thing is to not break the link from start to finish. This needs to become part of the workflow.
This info is important to professionals who have their images output with many different printers. This is what I know so far. I am also learning more.
P.S. If you plan to use this work flow by calibrating your monitor and are using a Windows based PC make sure you have a ATI Card to run the monitor. From what I've been told Windows based PCs do not have a standard
like Mac.

[dwalker]

To Michael Gomez and Charles Beasley:

I have read both your posts with interest. My next step is to send the file to a lab. I'll post here again with the results.

Thanks to both of you for your explanations.:D

Doug Walker

[Gomez Photography]

Check out this link to understand ICC profiling.
http://www.adobe.com/support/techguides/color/colormanagement/cmsdef.html

[charles beasley]

Doug-You're welcome- it's my pleasure. I'll check back to see how your lab prints go.

Michael-good link, although anyone going from a digicam to RGB printers such as Kodak LED's, die subs and Fujis, or to inkjets needn't get bogged down in the CMYK aspect that that article says is a necessary ingredient.

[stephen]

I have used the Grey card and white card and find that I still get better results with the grey card exposed properly, this is done on a D30, two actually, A DCS proback, a Leaf contare xy and a 1D, I also use a Macbeth Color Checker and have compared all the results and still have found that the white card woks fine in a black matte studio but add a color backgound and the reflected light seems to through the balance off, as seen on the color checkers, I have also used calibration equipment and found the same results thought that was more a test of the color calibrator then the camera. So far I have also determined that there are better sources of grey with the kodak grey cards full frame the shades actually vary when checked throughing off your whole neutral point. Use the macbeth and focus tighter on the grey it seems to be substantially more consistane and also more expensive. Plus you should take care not to touch the color patches and to not allow sun to get to it. Lest we get some fading and you need to spend another $70.00. Oh another thing to watch out for is an assistant who likes to spill coffee on your color charts, that renders everything a bit off as well. Haha. Anyway I will still use the grey card and still shoot the first frame of every setting with a macbeth color checker and then do a Digital clip test later if needed. Funny thing is most of my fashion is gelled anyway after i whitebalance, then we stick on some 1/2 straw filters for a pleasing warm glow. Go figure.

Stephen