Using 18% gray card to render proper white balance
In a certain environment, the lighting condition may not be perfect and the pictures may pick up a certain tints that that needs to be corrected later. For example, you were shooting tungsten studio light and you forgot to adjust the white balance control. Or you were shooting in a gym or church that bans the using of flash. Or you forgot to remove the color filter from your lens and shoot a bunch of pictures.
Having a 18% gray card in any one of the picture allows you to quickly correct the white balance and display the right color. You can then apply the correction to the rest of the in one stroke. Back in the days when we shot slides, a lot of the serious photographers would shoot the first couple of frames of a 18% gray card before doing their real shooting. Just in case the processing rendered some color tints to the rest of the roll, the frist couple of frames would provide a guiding standard for calibrating the white balance..
The above pictures were shot with tungsten light with the camera's white balance at daylight setting. The pictures improperly picked up an orange tint.
We are going to demonstrate how to correct the white balance of this group of pictures with a simple trick.
Adding a New Level Adjustment Layer
Open the two pictures and make the one on the left active. From Photoshop's menu, click on Layer->New adjustment layer->Level. Press <Enter> to accept the default layer name.
The above level adjustment window will be open. Click on the middle eyedropper and the curser changes into an eyedroper. Position the eyedroper on the 18% gray card (the middle color) and click on it. With the Preview box checked, you will instantly notice the color tint of the pictures changes. Click on different area of the gray card until the picture displays the desired color color tint. Then click OK to accept the adjustment.
The new adjustment layer is added to the layer window as shown above.
The picture above shows the corrected corrected image.
Applying the same adjustment to other pictures taken with the same lighting condition.
Postion the cursor over the new adjustment layer. Drag and drop the layer onto the picture you want to apply the same adjustment, for example, the picture on the right.
Instantly, the pictures on the right adopted the same level adjustment as the one on the left, as seen below.
Caution
This technique would work only for pictures taken with the same lighting environment.
If you did not place the gray card in the picture, you may apply the eyedrop on an area of the pictures having the proximity of 18% gray. Most of the time, it will still works.
|
