首頁 ﹥ FAQs > 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.