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Photoshop and Chroma Key Digital Keying & Masking:
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digiphoto
Newbie
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5. December 2004 @ 13:24 |
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<h2><font face="Times New Roman, Times, serif"> Technique</font></h2>
<h4><font face="Times New Roman, Times, serif"><em> Step 1: Select the Color of the Screen to Use</em></font></h4>
<h4> <font face="Times New Roman, Times, serif">Choose Blue or Green – based on which color will NOT be present in the subject you are photographing or videoing. </font></h4>
<h4> </h4>
<h4><font face="Times New Roman, Times, serif"><em> Step 2: Setting Up and Lighting the Screen</em></font></h4>
<h4><font face="Times New Roman, Times, serif"> There is nothing magic, or complex, in setting up and lighting the scene, just a few simple rules that we have listed below: </font></h4>
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<li>
<h4><font face="Times New Roman, Times, serif"> Light the subject separately to the blue screen, but ensure that, if anything, the subject is NOT illuminated more than the background screen.</font></h4>
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<h4><font face="Times New Roman, Times, serif"> Ensure that the blue or green screen is evenly illuminated. Don't just guess this, it is the most important part of setting up the lighting, check it with a light meter. If this is not correct it will be more difficult to extract the subject at a later stage.</font></h4>
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<h4><font face="Times New Roman, Times, serif"> Light the screen with 500 watt quartz lights, positioned one at each side of the screen, angled at 45 degrees towards the screen, and about 3 to 4 feet in front. Don't over light the screen as this will wash out the color and the saturation of the color will be diminished. If you are using flash lighting - use a light meter to make sure you lighting is flat and even (no variations) accross the entire background.</font></h4>
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<h4><font face="Times New Roman, Times, serif"> Place your subject as far away as possible from the screen, 4 feet or more, as this will prevent color spill from the blue screen being visible on your subject. If you see spill or light falling onto the subject - block off or "gobo" the light causing the spill. </font></h4>
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<h4><font face="Times New Roman, Times, serif"> Light the subject with a soft light by using two sets of lights, position the lights left and right of the subject. Again, 500 watt quartz lights can be used pointing away from the subject into umbrellas, and angle them to bounce the reflected light onto the subject.</font></h4>
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<h4><font face="Times New Roman, Times, serif"> The subject may be lit to give a dramatic effect, however, you have to be careful that this does destroy the lighting on the background screen.</font></h4>
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<h4><font face="Times New Roman, Times, serif"> Place, if possible, a back light on the subject as this will help to control the amount of color spill from the blue screen. A straw or yellow gel may be helpful in accomplishing this, as yellow will help kill the blue color (if shooting a blue chromakey). If the amount of backlighting is too hot then the apparent rim lighting will become obvious and spoil the shot, so be careful not to over do it.</font></h4>
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<h4><font face="Times New Roman, Times, serif"> And that's it, its easy, just a few basic dos and don'ts! Now you are ready to shoot.</font></h4>
<h4><font face="Times New Roman, Times, serif"><em> Step 3: Take the shot</em></font></h4>
<h4><font face="Times New Roman, Times, serif"> Once the scene has been set up all that remains to be done is to take the shot. Meter on the subject and zoom in on the subject as much as possible, we know this is not always possible or that it will not give the composition that you want, but it will help to define the edges around the subject. </font></h4>
<h4><font face="Times New Roman, Times, serif"><em> Step 4: Making the Cut-out in Photoshop</em></font></h4>
<h4><font face="Times New Roman, Times, serif"> Use the Magic wand tool or Color Range feature to select the Blue or Green background in you imported image. If you got the illumination right the background should be selected easily.</font></h4>
<p> </p> <p> </p>
To find out more about Chroma Key Techniques - visit http://www.chroma-key.com/chroma-key_faq.html or http://www.chroma-key.com/
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