| Transparent photography |
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| Written by Alexis ISAAC | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Friday, 20 January 2006 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Demonstration of using 2 pictures of the same object on 2 different backgrounds to create a transparent picture of this object.
Test this with you webcam nowI have created a Flash application wich demonstrate this. It uses your webcam as the camera and your computer screen as the background. click here to test this.
Taking the picturesIn order to make transparent photos you have to take 2 shots of the same object on a black and on a white background :
The picture have to be taken exctly on the same position : the camera and the object mustn't move. Generating the alpha channelTo create the alpha chanel you have to compare the two pictures : If a pixel is the same on the two pictures then it must stay opaque if it changes then it must be transparent. Generating the black and white picturesAs we are working on a black and white background we will compare the two pictures on their luminosity
Comparing the picturesTo compare the pictures we'll have to invert one of the pictures then substract them. Inverting
SubstractionWhen you substract the two pictures you have the following image in result : This image can be used as the alpha channel of one of the 2 pictures taken to add transparency. Test with an actual photoOriginal shots
Final image Test this with you webcam now I have created a Flash application wich demonstrate this. It uses your webcam as the camera and your computer screen as the background. click here to test this.
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| Last Updated ( Saturday, 21 January 2006 ) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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