This is a
short tutorial on how to adjust an internet or
auction seller's pictures
to get accurate colors in rocks or gemstones.
Generally if a seller has at least one photo with a
plain white background this process is much easier.
However if you know that one of their stones has a
white area you can use this one photograph to obtain
accurate pictures of all their photos. If a seller
doesn't have any photos or backgrounds with white
simply ask them to send you some photos of the
material wet (if rough or slabs) with a plain white
background. I also request outdoor or natural light
if possible or the use of similar quality indoor
lighting such as SoLux if possible.
seller's original photo.
to see the REAL colors in this stone. Does the rock
have a light blue zone?
Photo adjustment to show
real colors. The light blue is actually more like
a gray color. The process to obtain this picture
is explained in the tutorial below.
A second rock from the same
seller. We know that noreena jasper has WHITE and no
light blue. This picture is
used as a "constant" or "control" since we know that
the light blue areas are actually white. If you have a
known white background then the background can be
used as the constant.
The fixed noreena jasper
photo showing the corrected white areas. Once you
adjust the white areas to look white then all the
other colors in the photo are fixed as well.
I use Corel Paint Shop Pro Photo XI to make
adjustments. The nice thing
about this program is it can save your last
adjustment settings so after the first adjustment
you can add pictures quickly and fix them.
Open picture with known white area in the program
and go to Adjust-Color Balance.
Use the slider to adjust the picture so that the
light blue turns to white. Set Settings to "Last
Used". Hit "OK".
After clicking OK in the last step you now have
the corrected image displayed.
Now you open a different picture from the same
seller. I picked this jasper because I don't know
any of the colors in this stone. But since I know
the color shift of the noreena I can use this
knowledge to extrapolate the correct colors of this
rock. Based on the last stone I'm guessing that the
light blue color band in this rock really isn't this
Same process as before but this time it's easier
since the settings were saved from the first
adjustment. To be sure, look and see that "Last
Used" is selected under "Settings" when the next
Window opens and previous settings are
automatically displayed. Simply hit "OK" and photo
is color adjusted.
So here is the final picture showing accurate
colors. Note that the areas that appeared to be
light blue are actually more of a gray color.