Postage STamp Watermark

I am trying to read the watermark on some postage stamps by scaning them or by scanning them with a film scanner (shining light thru the stamp.)

I can make the watermark visable using color adjustment on some stamps but not all.

I would appreciate any suggestions.
Regards
Tom

"collector tom" wrote in message

I am trying to read the watermark on some postage stamps by scaning them or by scanning them with a film scanner (shining light thru the stamp.)
I can make the watermark visable using color adjustment on some stamps but not all.

I would appreciate any suggestions.

One idea would be to use a flatbed scanner that supports transparency, scan the same stamp by reflected and transmitted light, superimpose the two images in difference mode, effectively using Photoshop to subtract the images from one another. If you have access to a digital camera, try doing the same thing, only using backlight from different angles. --
Mike Russell
www.curvemeister.com

Thanks Mike.

I have attached some files of the stamps to see if you can get to the watermark.

http://www.frontiernet.net/~collectorsel2/postagedueslide.jp g

http://www.frontiernet.net/~collectorsel2/pdneg.jpg

http://www.frontiernet.net/~collectorsel2/postageduewatermar k1.jpg

http://www.frontiernet.net/~collectorsel2/postagedue6.jpg

Thanks for your help

Tom

"Mike Russell" wrote in message

"collector tom" wrote in message

I am trying to read the watermark on some postage stamps by scaning them or by scanning them with a film scanner (shining light thru the stamp.)
I can make the watermark visable using color adjustment on some stamps but not all.

I would appreciate any suggestions.

One idea would be to use a flatbed scanner that supports transparency, scan the same stamp by reflected and transmitted light, superimpose the two images in difference mode, effectively using Photoshop to subtract the images from one another. If you have access to a digital camera, try doing the same thing, only using backlight from different angles. --
Mike Russell
www.curvemeister.com

Have you tried going to the store and getting a whole stack of colored cellophane in every color you can find and putting it between the scanners light and the stamp. (or go to the store with a stamp or two and try it in the store) By changing the color you might be able to get different results.

I don't know enough about color theory and pigments, but I bet if the ink color is blue and you scan with a red sheet under it and then scan with a blue sheet under it, you will get very different results as long as the pigments let light go through them. If they are truly opaque, you might not be able to scan the printed area and you could just separate out the areas where there is no pigment.