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-   -   Matching colors - need help (https://forums.steves-digicams.com/tips-tricks-71/matching-colors-need-help-125994/)

whatmework? Jul 20, 2007 5:02 PM

1 Attachment(s)
Hello all,

I need some help with color management. I know little about it, so go easy please ;-)

What we are doing now: I have a dental practice where we do a lot of cosmetic work for our patients. We use a digital camera (XT Rebel; 100mm macro lens; ring flash) to create pics which are then emailed to our lab. The lab uses the image on their screen as a reference as to the exact shade to make the new crowns.
http://picasaweb.google.com/jnebenzahl/SampleShade
The photo shown is an example of how we convey the image. The sample shade tooth is one of a series of standardized shades used in dentstry. It is in the picture to serve as a reference. (This is a really knarly mouth -- not our usual patient. It was the only picture I had available here at home!)
http://picasaweb.google.com/jnebenzahl/SampleShade
The Problem: We are not getting accurate color representation on the computer. I know that all montors should be calibrated. We've never done that but I'm ready to start, but I'm also concerned that the image from the camera is a as accurate as possible. There are very subtle differences in tooth color that are important for us to be able to discern. Ideally, the shade of the sample tab we hold in the photo, should appear on the monitor as in real life.

What I need: It would be great if someone could offer a way for us to take pictures, email them, and have the viewed result on the lab's computer, appear the same as it does in real life.

I would really appreciate anyone's thoughts or sugggestions how we could do this.

Many thanks!

pcs34109 Jul 22, 2007 1:06 PM

Hi,
Do you have photoediting software? If so, there should be a tool to "pick up" the color. I use PSE 5 and there is an eyedropper tool. It will give you the RGB coordinates as well as the HTML code. Some colors are websafe, meaning they will be true, and some aren't. Here is a link to a site that will show websafe and not safe. http://www.ficml.org/jemimap/style/color/wheel.html Hope this helps.

pcs34109 Jul 22, 2007 1:10 PM

Don't know what happened to the link. Some extra characters were thrown in at the end. Should end with html. Delete anything after that. http://www.ficml.org/jemimap/style/color/wheel.html

VTphotog Jul 22, 2007 3:15 PM

It starts with the camera, of course. Are you using the flash WB setting, or auto WB? Variations in lighting (ambient) can cause WB to be read differently in auto mode. Ideally, you should set up a custom WB using a white or grey card and your ring flash. This should give you the most accurate representation.

If using email, the question of web safe colors should not enter. You do need to have an image editing or viewing program which can display the RGB values of the color in question. This will help determine if any color cast is present, which can happen. Digital cameras create images which the mfr determines are pleasing to the eye, not necessarily accurate, so the tone curves of the primary colors get adjusted by the camera depending on what type of scene it thinks is being shot. If you can shoot in fully manual mode, or access the menu to disable any scene modes, it should help also. (I'm not familiar with your camera's operation, as you may have guessed)

Checking it all would involve taking a picture of a gray scale card, and displaying it on both monitors involved, checking the RGB values first to make sure it is gray (RGB values the same from dark to light), then adjusting your monitors to get correct output. Probably would want to use a calibration tool ( spyder or some such).

If you just need colors to be correct relative to your sample, then just the last should be all you need to do.

brian

whatmework? Jul 22, 2007 7:04 PM

:cool: Thanks to you both, pcs34109 and Brian! Your replies brought me to one of those, "Ah ha!" moments. It sounds like once the custom white balance is set and the monitor is calibrated, I should be in good shape. I ordered a gray card today.

Thanks!



pcs34109 Jul 22, 2007 11:01 PM

I'm sprry if I gave incorrect information, but I thought the photo that was provided was acceptable and the color needed to be duplicated.... Anyway, VT photog, do I understand by your handle that you are a Virtual Tour photographer? If so, I am also. What technology do you you use?

pcs34109 Jul 22, 2007 11:11 PM

Ok, I should have investigated before I asked. I now realize that VT, means Vermont, and NOT Virtual Tour. Mea Culpa, again.

ICC_Color Jul 25, 2007 10:53 PM

You shouls take a look at http://www.perfxshots.com for digital camera profiling.

ICC_Color


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