Here's an experiment using an orange piece of cardboard as my background. I replaced that background with black. That should enhance any flaws in the replacement. Original photo at http://the-rna.com/chroma/test.jpg Processed photo at: http://the-rna.com/chroma/dest.jpg The following command was used (convert is part of the Imagemagick suite): $ convert test.jpg -fill black -fuzz 20% \ -draw 'color 100,100 replace' dest.jpg This command: i) Specifies a new background color of black. ii) "Blurs" the image before processing to even out the background. iii) Selects the color at the point (100,100) near the top left of the image as the color to be replaced. This pull tab will be reasonably representative of the pieces I want to apply this to. This almost works. The problems that I see are: 1) The background is not very even and there are some defects. This should be correctable by using a more even background. 2) Some of the original background is being reflected around the edges of the subject. I don't see any way to fix this. More experimentation is needed. 3) Some of the original background is being reflected off the top of the subject. This is most obvious at the wide end of the tab. 4) Some areas around the edges of the tab did not get filled in. This most obvious in the notches at the base of the "ring". I think this is because of shadows. I think this best resolved by elevating the subject as was previously described using Saran Wrap. I think I will try: a) Elevating the subject. b) Less illumination on the background. c) Illumination from the sides for the subject. The ring light I used for this experiment will probably cast a lot of light on the background causing the same reflection problems. FUN FACT: Those of us at lest in our fourties recognize this as a pull tab. This particular tab probably came from a Pepsi product. The ring and the tab could be separated. The thin end of the tab was inserted into the notches at the base of the ring. Pull back on the ring to apply some tension. Let go of the ring, the tab springs back and sends the ring flying. When used this way we called them "flingers". With some practice a fairly good aim could be achieved. The removable pull tab was outlawed (I think) in the early eighties. This particular tab was found on the ground last summer in Akron Falls part (Akron, New York). Tim On Mon, 2009-12-21 at 13:45 -0600, David Dyer-Bennet wrote: > On Mon, December 21, 2009 13:34, lookaround360@xxxxxxxxxxxxxxxxx wrote: > > > Que Saran Saran? Whatever will be, will beee. > > And stay fresh in the refrigerator! > > > Construction hints: > > Stretch the SARAN on the hoop fairly taunt and then hold it near a warm > > light bulb and it will draw perfectly tight. A big, translucent white > > plastic bucket or waste can is great for a base. You place various > > background material in the bucket. I used a selection of colored craft > > felt. Side lighting through the bucket gives some extra effects. > > (continues taking notes) > > This would be particularly useful for some of the jewelry shooting I've > done, I think. Some other stuff is a bit too heavy to be supported this > way I guess (haven't done testing yet!)
