Everyone's technique for background deletion has merits, but the
bottom line is that if the original photo of your shell is poorly
illuminated with heavy shadows and dark areas, turning the background
to a solid black color will be more than challenging no matter how
advanced the program's background tool algorithm is.

Photoshop has overall more powerful editing tools, yet I use
Paintshop Pro (PSP) version 11 on a daily basis for adding shell
images to my Web site.  Its ease of use with rapid results cannot be
beat.  I started using PSP years ago with version 3.  I stopped
upgrading PSP with ver.11 after Corel bought out JASC, the original
creators of PSP, and took the software in a different
direction.  With ver.11 PSP was a close equal to Photoshop, the
industry standard for image editing tools.  I can effectively
photograph (using the TWAIN function), composite and "clean up" a
shell image within minutes, all with the one program.

The most simplified method involves using the "fill" tool.  As
mentioned, start by photographing your shell(s) against a
non-reflective black background making sure it lays completely
flat.  Remove as much dust as possible using a lint-remover
roller.  The more complex a background, the more difficult it will be
to achieve a pure black BG.

Secondly, if all of the outside edges of your shell are well
illuminated and the shell is of a lighter color, use the PSP
background or flood-fill tool and start by adjusting the fill
"tolerance" setting to a moderate number (such as 20).  Set the color
to pure black (html #000000 or RGB to 000).  Click the background
with the fill tool and the background should totally black out.  If
the tolerance setting number is too high, the black will bleed into
the shell image in the darkest areas -- set it too low and the
background will not totally "black out".  Trial and error with the
tolerance setting will get you to a base line number from which you
can then adjust for the reflectivity of the shell.  The technique is
a bit more challenging when a shell is dark.  Using a light(er)
colored background is your best bet.  Filling the light colored
background with black is essentially done using the same process.

Even with a lint roller, dust spots invariably show up on a
photographed black background and can be touched up with either the
paint brush tool set to the same "000" black color or with a higher
fill level.

BTW Marien, your suggestion to temporarily view the picture as a
negative image effect is brilliant!  It does reveal any and all
background imperfections that can then be touched up after undoing
the negative image effect back to a positive image.  Though more
complex the "magic wand" tool is also a very effective method to
place a shell image over a pure black BG.  More recent versions of
PSP also have a "background eraser" tool that is even more powerful
that the basic fill tool, but a discussion of these techniques is far
outside of the Conch-L subject area.  So here are a few links
...  http://campratty.com/4tooltours/kz/bge1.html,
http://mrswizard.com/eraser_tool_and_tubes_paint_shop_pro_xi.html,
http://graphicssoft.about.com/od/paintshoppro/ig/lesson2/Eraser-Tool.htm

No doubt this may all sound like a bunch of gobbly-goop if you have
never used or experimented with these tools.  Don't let a little
complexity scare you away from experimentation.  These tools work,
and they work well.  The power of these image editing tools are
waiting to be revealed.  Then the value of doing your own shell image
editing will truly become evident.

Rich
~~~~~~~~~~~~~~~~~~~~~~~
www.worldwideconchology.com
~~~~~~~~~~~~~~~~~~~~~~~




At 11:17 PM 2/7/2012, you wrote:
>Unless you have photoshop skills, it's not easy, but possible. Best
>to get someone who knows how to do it for you - if the edges of the
>shells are spiny or irregular, and if there is not a lot of contrast
>between the edge of the shell and the existing background, good
>results take a level of expertise that I have not mastered.
>
>If you have a lot of time and a lot of patience, you can use Paint -
>the old version is much better. Blow the picture up to max
>magnification, then place a black border, pixel by pixel, around the
>shell a few pixels wide. Then you can use the other tools to blacken
>the rest of the background.
>
>And from now on, take yer photos on a piece of black velvet.
>
>mike
>
>On 2/6/2012 10:01 PM, Ron G. Noseworthy wrote:
>>Hi, everyone!
>>
>>I am preparing some color photos for a paper.  I am using Photoshop
>>and need a black background for the specimens but I don't know how
>>to achieve this effect.  If some on the list can help me, I would
>>really appreciate it.
>>
>>All the best from Korea!
>>Ron Noseworthy
>>
>>

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