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Best Color Calibration with X-Rite ColorChecker Passport and Adobe Photoshop Camera Raw Software
The best color calibration for digital photographs is achieved with the combination of a gray balance adjustment and the use of a custom DNG camera profile. The X-Rite ColorChecker Passport provides the reference color target and software to make a custom DNG camera profile which is used to calibrate the color in your digital photos. The DNG profile does not set the white balance; therefore, the additional step of adjusting the gray balance of your photos in Adobe Photoshop® is necessary to remove unwanted color casts.
To use this workflow, you must set your digital camera to record photos in the raw file format and open the raw files with the Photoshop Camera Raw plug-in. Adobe Photoshop automatically launches the Camera Raw plug-in when you open a raw file from Photoshop.
Note: This approach works equally well in Adobe Lightroom.
Step 1
The first step in this workflow begins at your photo shoot. Place the X-Rite ColorChecker Passport and a gray card in the scene and take a picture (see example photo below). For best results, the ColorChecker should be at least 10% of the total image area. Make sure the photo is recorded in the Raw file format. This will be your reference photo for building a custom DNG camera profile and a custom gray-balance setting. Continue with your photo session capturing photos with your digital camera until you have a new lighting condition. Take a reference photo, with the ColorChecker Passport and gray card in the scene, for each new lighting condition that is significantly different from an earlier lighting condition.
Note: The set of color patches on the X-Rite ColorChecker Passport includes six neutral patches. Either of the two medium-gray neutral patches can be used as the gray object in the scene for the custom gray-balance adjustment. I personally prefer to use the Robin Myers Digital Gray Card (shown in the example photo below) as the gray object in the scene for the custom gray balance adjustment because the surface area is larger which allows me to frame a larger scene and still have the gray card appear large enough to easily implement the gray balance adjustment.
Step 2
You must convert your reference shot raw file into the Digital Negative (.DNG) file format in order to use the X-Rite software to make a custom DNG camera profile. When you are ready to work on the photographs on your computer, open the Raw file for your reference photo (i.e. photo that contains the ColorChecker Passport in the scene) in Adobe Photoshop. Photoshop will automatically launch Adobe Camera Raw and you will see your photo displayed in the window. In the lower left corner of the window, click on the Save Image button. The Save Options dialog box will open (see screen shot below). Select the Destination folder where you want the file to be saved. Choose a File Naming format. For the File Extension choose .DNG. At the bottom of the dialog box select Digital Negative for the Format. Select Camera Raw 4.6 and later for the Compatibility. Then click on the Save button. You can continue this process to convert the raw files from additional reference shots into the Digital Negative file format.
Step 3
Close Adobe Photoshop. This step is important because Photoshop will not recognize the custom DNG camera profile you are about to create until Photoshop is closed and reopened. You will open Photoshop again in Step 5.
Step 4
Launch the ColorChecker Passport application and follow the instructions shown at the left side of the screen (see first screen shot below). After the application loads the DNG file and automatically detects the image of the ColorChecker, click on the Create Profile button at the lower right corner of the screen (see second screen shot below). A Save dialog box will appear. Give the profile a name and select the folder where you want to save it. Then click on the Save button. You can continue this process to create more DNG camera profiles from additional reference shots.
Step 5
Open Adobe Photoshop, and then open the first reference shot raw file that you want to adjust (e.g., the reference shot with the gray card or X-Rite ColorChecker Passport in the scene). Photoshop will automatically launch Adobe Camera Raw and you will see your photo displayed in the window. You will make a gray balance adjustment to this photo and save the setting for use on other photos.
Step 6
In the upper right corner of the window you will see a series of icons. Click on the Camera Calibration icon (The icon looks like an SLR camera.). Then select the DNG camera profile that you created in Step 4 from the Name menu (e.g., Park-Sunlight is the DNG camera profile that I created for the photo taken in a park with direct sunlight). You will see changes in the colors in your photo. From my experience, the changes are most obvious in the blue hues.
Step 7
Now it is time to make the custom gray balance adjustment. In the upper left corner of the window you will see a series of icons. Click on the White Balance Tool icon (The icon looks like a partially filled eyedropper). Then click your cursor on the gray object in the scene to apply a custom gray balance. A gray balance adjustment will be applied to the image to make that point in the image a neutral gray (e.g., R=G=B for the pixel values for the three color channels). The gray balance adjustment is now finished.
Note: I do not know why the tool has the name "White Balance Tool." The result of using the tool is a custom gray balance similar to what you will get when using the Curves adjustment in Photoshop. I will assume that the name is intended to conform to digital camera terminology where "white balance" is the preferred term.
Step 8
Now save the custom White Balance and Camera Calibration settings. Go to the top right corner of the controls window and click on the menu icon. Select Save Settings (see screen shot below).
A full menu of settings will appear on your screen (see screen shot below). In the Subset menu at the top of the screen select White Balance. Then click on the check box next to Camera Calibration to add that to the settings list. Now click on the Save button. A Save Settings dialog box will appear. Give the settings file a name and click on the Save button to save the custom settings file.
Step 9
Open the first photo that you want to adjust in Photoshop. Go to the top right corner of the controls window and click on the menu icon. Select Load Settings and choose the saved settings file for the custom White Balance and Camera Calibration (i.e., the file saved in Step 8). These settings will be applied to the image on your screen. You can continue with other adjustments to the image in Camera Raw or click the Open Image button at the bottom right corner of the screen to open the image in Adobe Photoshop.
Step 10
Repeat Step 9 for all photos that you want to adjust that were taken with the same lighting condition. To work on photos that were taken under a different lighting condition, repeat Step 2 through Step 9.
The X-Rite ColorChecker Passport has many useful features. On this page I described how to use the X-Rite ColorChecker Passport to create a custom DNG camera profile. The medium gray neutral patches on the ColorChecker Classic Target panel can also be used for the custom gray balance adjustment with the White Balance Tool in Adobe Camera Raw. The X-Rite ColorChecker Passport has two more panels: Creative Enhancement Target and White Balance Target. The Creative Enhancement Target has warming and cooling patches and can been seen and captured in a reference shot with the ColorChecker Classic Target (see photo gallery). The White Balance Target is on the back side of the Creative Enhancement Target panel, so the White Balance Target cannot be seen and captured with the ColorChecker Classic Target. The White Balance Target is best used as the neutral reference object for creating a custom white balance setting in your digital camera.
Click on this link to the photo gallery with example images to see variations of the processed Raw file.
Robin Myers Digital Gray Cards
The links below will take you to the Robin Myers Imaging Web site where you can purchase the product featured in the link.
Digital Gray Card (Small): RMI Price $14.95
Pocket size 10 x 15 cm. (approximately 4 x 6 in.)
http://store.rmimaging.com/digitalgraycard-100.aspx
Digital Gray Card (Large): RMI Price $29.95
Camera bag size 15 x 22.5 cm. (approximately 6 x 9 in.)
http://store.rmimaging.com/digitalgraycard-150.aspx
Note: To learn more about digital raw capture and raw files, follow this link to a PDF on the Adobe.com site.
Note: Photoshop is a registered trademark of Adobe Systems Incorporated in the United States and other countries.