I had the good fortune to work with a beautiful young model this week and do a creative green screen photo shoot in my studio. Green screen technology is most commonly used in cinema and TV - you see an example of it every evening if you watch the weather report on your local news broadcast. It's pretty simple - a elastic sheet (elastic is important because you don't want wrinkles in the screen) or painted surface such as a wall is colored a very specific color of primary green. It has to be uniform and the hardest part of making a green screen work is lighting it consistently. You film or shoot whatever photos you are going to shoot/take - and the next most important thing about green screen usage is getting good separation between your main subject and the screen. You do NOT want any green light to splash off the screen onto the actor/model. So you need to understand lighting - key/fill/background/back light - I often use a 5 or 6 light setup. Sometimes I use more. After you've taken your photos or shot your video/film footage, the images with the green screen are brought into whatever software you are using and a "CHROMA KEYER" is applied. What a chroma keyer does is identify the specific green of the screen and makes that color unavailable - thus making it invisible. Now you have your main subject floating in space and you can put whatever background you want behind them.
ABOVE - The model for this shoot sits on the floor where I have several lights on her and on the screen behind her. What is important is that I am matching light from a photograph that I want to specifically place her into. Matching light sources, light temperature (color), and intensity is very important if you want to get realistic results. When the green is keyed out and she's left floating against a transparent background - the image put behind her (or the video footage if this was a video/film production) is called a "PLATE".
This is a rough keyed image - I had to manually cut out the carpet beneath her - and there's green on her arm and in her hair. But this is a rough and it's OK to get started with. I'll use Photoshop to remove the green tint from her skin and hair - then I'll take a very soft brush eraser and gently remove the blocks that form her hair (above her arm to the left) so that it will look more realistic. FOR THIS DEMONSTRATION - THE WHITE BACKGROUND WHEN SEEN IN ANY PHOTOS ATTACHED TO THIS CARD REPRESENTS EMPTY - TRANSPARENT SPACE.
ABOVE - This is the plate that I have selected. There are always issues inherent in working with photos and green screens such as perspective and focus. This image is perfectly focused for deep-field viewing - as a photo of such a magnificent structure like The Great Wall should be. But we need to trick your eyes for this illusion to work. That means adding simulated DOF that is more appropriate for a portrait. Also, the steps to the right cause a serious perspective issue. For the illusion to work I need to put the model in the center of the walkway - and there's a slight mismatch in perspective and scale that the steps won't allow me to hide. So I need to get rid of the steps.
ABOVE - I simply make a copy of the wall and walkway opposite of the steps, reverse it horizontally, and move it over to cover the steps. I have to clone the wall above the steps and carefully transform it down - shifting the perspective manually - to make the illusion complete. I then blend by erasing with a very soft eraser tool.
ABOVE - The end result of copying and blending the walkway and wall to hide/erase the steps and platform that were there. Now it's time to add the model and position her.
ABOVE - I add her and put her in a place that I think works the best. She's obviously and oddly not natural here - but the scale and perspective work. Now I can start making the illusion look real. Now it is time to trick your eyes!
ABOVE - I'm going to start with the most obvious thing wrong with our model's appearance at The Great Wall - she lacked a shadow underneath her. I'll do a very soft shadow using Alien Skin's "EYE CANDY 7 - PERSPECTIVE SHADOW" filter. At about 40% opacity.
ABOVE - I'll then go back into EYE CANDY 7 and add another shadow - this one on the wall behind her - something that the strong key (or primary) light source on her and the walkway around her would create. I'll blend the shadows with a soft eraser tool and then color correct her - matching the color, tone, and shadow depth of the rest of the image using the CAMERA RAW FILTER in Photoshop. I love the CAMERA RAW FILTER - because you can control and alter so many variables with one powerful plugin/filter. Now it is time to prep the background.
ABOVE - The first thing you should understand is how focus shifts with lenses. You have what is called "FOCUS DEPTH" - which is a range of space from the focal plane of the camera where focus will come in - then a range where it will hold - then a range where it will go back out (drop off). This means that if you set your focus to an object 20 ft from the focal plane of the camera - there will be part of the frame before your subject where the image might not be in focus, then focus around the subject - then focus dropping off to the point where everything past a certain distance is out of focus. For an illusion such as this to work, you must think about what should and shouldn't be in focus. I made 4 copies of the background plate into 4 new layers. In the first layer I cut out everything but the wall that would be closest to the camera up to the point I want focus to come in for the main subject. I erased EVERYTHING but this one section of wall in this single layer. I then applied a lens blur and then added a gradient transparency to blend the focus - when I place the perfectly focused image behind this one (in a layer below it) the effect will be focus that is blurry - coming into an area where focus is good.
ABOVE & BELOW - I create the same illusion in reverse - for the sections of wall where focus will fall off.
BELOW - I create a general focus blur for the rest of the background.
BELOW - When all 4 layers are merged together you get the blurry sections of your photo.
BELOW - When you add the original layer - in perfect focus - below this layer and it's transparent areas - you get an image with an approximation of what focus with a lens set with a large aperture would create.
BELOW - I then take the entire flattened new image into CAMERA RAW FILTER - and using the lens adjustment tool I add vignetting.
BELOW - Now I add the layers with the model back in to get a much better idea of how well the illusion is going to look.
BELOW - I realize I need to work on the color of her feet and add more shadow beneath her back foot to make it look as if it is resting on the walkway. I also crop the entire image to make her more prominent and conform to a RULE OF THIRDS composition design.
BELOW - I flatten the image into a single layer and I open it in Alien Skin's EXPOSURE 7 Plugin - where I can fine-tune color, focus, and simulate countless film stocks.
BELOW - I decide to add a little more shadow to her rear foot (again) - I'm still not happy with it. I also do some more color fine-tuning. FINALLY happy with the way everything has come together it's time for a VERY IMPORTANT set of filter applications to complete the illusion. I will open the image in EXPOSURE 7 and add a uniform amount of film grain - add more vignetting to the image, deepen (crush) the shadows and dark areas. And add a split filter - cooling the background slightly while warming the foreground - this assists because in photography the illusion of depth is assisted by the rule - cool colors recede and warm colors pop forward.
ABOVE - The final touches of the finish image include the addition of my watermark and a final run-through in CAMERA RAW FILTER - where I tweak the colors a little more - add a little sharpness - and adjust the luminescence to blur the grain some - which blends the grain across the entire image - giving you a uniform grain pattern for ALL parts of the image.
This is how you can use a green screen and Photoshop to visit The Great Wall of China without ever leaving your house. Imagine how cool this is going to look when you put it on your FB page... LOL.
© Copyright, 2015, Jon Patrick Hyde, All Rights Reserved.