Home ﹥ Custom Page > FAQ - Camera DCC Filter > ☉ What's wrong with Gray Card or White Card?
☉ Why can’t obtain the exact Visual Color Photo from using the “White Card” or “Grey Card”?
There is an
important basic concept to be understood that the color of light is the color temperature
itself. When the light is
projected onto the surface of object and reflected from the object,
the original light is also doing the color rendering effects on the
object surface.
Gray world theory based on an ideal world, it
says that its integrated reflectivity is18% if all the objects in
all the colors of the world were put together. In reality of real
photographic scene, the integrated reflectivity could be vastly
away from 18 degrees gray due to the insufficient samples of the
objects and inappropriate proportion of certain colors to other
colors. It is great to use Gray Card for purpose of
exposure. However, neither
white card nor gray card is suitable for white balance since it is
tinted by ambient lights that make it as an “incorrect” color
standards as shown in the comparison photos indoors or
outdoors.
When a variety of ambient lights are projected
on the gray card or white card, these original “standard gray card”
or “standard white card” has been subject to varying degrees of
color rendering (light pollution). To camera’s color compensation system, these
tinted “standard gray” or “standard white” was not the accurate
value any more. By using these color inaccurate “gray card”
and/or “white card” reflected light for the manual white balance
purpose at scene or use the photos of them to adjust the color
temperature adjustment afterwards with application, the adjusted colors would certainly differ
from the true color of the actual photographic scene.
You can easily make use of the aforementioned “How to get Visual
Color” to compare the colors differences with the actual scene
colors and the calibrated colors from using “gray card” or “white
color”.
Under complex light sources, the
grey card would be tined to
various degrees of grey color which is reflected to camera for
white balance at different locations of the shooting
scenery. In such case, it would be a nightmare to adjust the
color of each photo even using the best PS skills.
Only “Raynauld™
Directivity Color Calibration Filter” can be used to take the
framed photographic scene incident lights that are absorbed,
homogenized and diffused through its neutral entity filter to
camera’s sensor to provide the most accurate Color Calibration
compensation value toward the camera’s gray card system to
capture the almost perfect mirror image color photo/video in
one shot.