Michael For small items like coins and jewelery, and you can shoot from overhead, serran film (plastic food wrap)stretched taunt in an embroidery hoop is magic. You lay your background behind that. The object appears to float in space. I can provide a little more detail if you like. AZ LOOKAROUND - Since 1978 Build a 120/35mm Lookaround! The Lookaround E-Book FREE COPY http://www.panoramacamera.us > -------- Original Message -------- > Subject: [SPAM] Re: Chroma Key and macro photos > From: Tim Corio <tcorio@xxxxxxxxxxxxxxxx> > Date: Sat, December 19, 2009 8:07 pm > To: List for Photo/Imaging Educators - Professionals - Students > <photoforum@xxxxxxxxxxxxxxxxxx> > Oops. I missed an important requirement. I am taking photos of items > that I may never have access to again. To use these photos for > different purposes I want to be able to change the background at will. > For a projected presentation I would give them a black background. For > publishing in a book I would give them a white background. I'm sure > that I'll come up with other uses over the years. > For round coins I wrote a script that uses edge detection to find a > bunch of points on the edge of the coin. Then I calculate a best-fit > circle. Using Imagemagick I then mask out the background (anthing > outside the circle) and replace it with whatever color I want. > This method will be easy to extend to items that are more-or-less > convex. But complicated shapes with many holes will be difficult to > handle like this. The most complicated items I am likely to encounter > are badges consisting of a pin with small chains suspending a medal. > This is the type of medal that a person would wear pinned to their > lapel. These items will have the background showing through around the > medal and the pin as well as between them and and through the links of > the chain. > Since I may have to handle dozens of these in a given day it's not > practical to do it manually. I think chroma-key is the way to go. But, > I am open to other suggestions. > Thank You, > Tim > On Sat, 2009-12-19 at 17:53 -0500, michaelhughes7a@xxxxxxx wrote: > > In a message dated 19/12/2009 22:36:32 GMT Standard Time, > > tcorio@xxxxxxxxxxxxxxxx writes: > > My first thought is to > > find an opaque piece of blue plastic and light it from below > > > > If the material is opaque what is the point of having a light below > > it. Did you perhaps mean translucent blue plastic material, > > > > For display purposes black velvet is often used as a background in > > showcases designed for ordinary viewing. > > > > > > Michael
