Green screen photography: Capture
Personal experience
A colleague and I did a large project involving green screen photography last year, and here are a few words about what we learned from that experience.
There are quite a few sites with blue- and green screen tips and tutorials out there, but most concentrate on video, which is a little different from photography. Whether you should choose green screen or blue screen is much debated, but there seems to be a general understanding that green is better for photographing people since it is further from skin color.
The green screen
The whole point of the green screen is to get an image with a background that’s easy to erase afterwards. If you´re on a budget, you can probably achieve this by painting a wall in the right color, but to avoid reflections you’d be better off using fabric. The background should be large enough to give the photographer some freedom of movement.
Lighting
Using separate lights for the background and the models gives more control over the lighting. The background should be lit evenly and not too brightly. Position the model as far from the background as possible to avoid spill light from the background on the model and shadows from the model on the background. Use barn doors or black screens to further protect the model from spill light from the background. A hair- or separation light hitting the model from the back also helps reduce green spill light.
Casting
Hiring professional models saves a lot of time and frustration, and ensures a better result. This is time consuming work, and a trained model helps getting it right the first time
Styling
The model should obviously not be wearing anything green, but this is less crucial for photo than for video as long as the color is not next to the background. Avoiding loose hair, curls, higly reflective or semi-transparent fabrics and furs etc. will make post production much easier.
Shooting
A photographer will always be tempted to compose the image in camera, but in this case that’s not a good idea. It’s important to allow for a little air on all sides of the model to make the pictures more flexible to work with later. You can always cut off half the head in Photoshop, but painting it in because it was cropped in camera is far trickier…
The photographer should avoid using selective focus. Objects that are out of focus get blended with the background, which makes it really difficult to separate them afterwards. Use an aperture small enough to ensure sufficient depth-of-field to get the entire model in focus, including contour lines. If you absolutely must have selective focus, I would recommend faking it in photoshop afterwards instead.
The image should be slightly overexposed rather than underexposed, but this goes for all digital photography. By shooting in the RAW format, you will be able to tune the white balance losslessly in your RAW editor of choice afterwards.
Stay tuned
Check back for a follow up on keying and color adjustment!
August 14th, 2007 at 9:48 pm
still checking back for that follow up on keying and colour adjustment…
August 15th, 2007 at 11:16 pm
Hi Nick,
Thanks for the interest, and sorry for the delay. I’m busy following up on the Abduction Lamp and being a father these days, so it might take a little while before I get time to finish that article.
I will send you an email when I post it!
Lasse
December 4th, 2007 at 1:59 am
Great tips - we just posted a little visual example on our blog of the cutout process (which software makes incredibly simple - http://pulp.orangephotography.com/blog/archives/2007/12/green_screen_ph.php)
January 28th, 2008 at 5:16 am
We are looking at using green screen for our school photography program in 2008. We do over 2000 students, but were thinking about testing it out on out Spring shoot program which only draws about 500 kids.
What problems do you for forsee we will have on this scale and variation of subject. We can advise the type of clothing and advise to keep hair neat and cropped, but you know what people are, and we dont want to be there cleaning up too much in photoshop. What do you think?
Regards
Richard
January 28th, 2008 at 12:02 pm
Hi Richard,
The project that we did was for a corporate image library, so the requirements for the images were very high. We had to deliver high resolution images with a perfectly clean alpha channel and without color spill. Because of this, we had to do quite a bit of manual color adjustments and even manual adjustments (hand drawing) on the alpha channels for each image. It took about an hour for each image, but since we were only delivering about 15 images, so this was absolutely doable. The quality turned out to be very good after we were done witht the images, and they have now been used in everything from newspaper ads, magazine covers and large posters with very good results.
I am guessing that your project will be quite different from ours, and that you will need far lower resolution images to be printed in a smaller scale? Maybe you can even live with a little lower quality and some minor color spill? These are considerations that you should think about before you start, as they will determine how much work you need to put into post processing. But whatever you do, you would still want to shoot at a higher resolution and scale down after you are done keying and adjusting the images to have as much detail to work with as possible.
In your case, with 500 - 2000 images, you will have to be sure that you have a workflow that can be performed mainly by batch processing in Photoshop or in your keying program of choice. The previous post from gene x shows that a workflow like this is possible, especially if you are not going for a “perfect” image. Gene x’s images are as I understand the result of using just a keying software without further adjustment, and they certainly do the trick for this kind of images. They do have a slight green halo on parts of the subject, but I think it is a good trade off between time and quality. Assuming that none of the subjects have anything green on them, the images could easily have been batch processed to remove the halo by simple Photoshop filtering. But again, for this kind of project, maybe it is not necessary to go any further?
I would not recommend that you shoot the first 500 images without having done a test shoot and post processing of the images beforehand. You will most certainly run into some challenges that you will be able to correct before you start pulling 500 students into your studio. You would not want to have to do that more than once.
It has been a couple of years since we did this project. We evaluated a lot of different packages before doing our project and ended up using Primatte Chromakey from Digital Anarchy as a Photoshop plug-in. It had the best interface and gave the best results at the time, but other programs may do this better today.
Good luck, and please write again if you have more questions,
Lasse
May 11th, 2008 at 7:19 am
great tips on green screen usage. thanks!
June 4th, 2008 at 12:52 pm
Check out my ebook that explains how you can make human extractions from green screen with less perfect lighting in just five minutes! Not much of a time and you will retain full hair detail as well!
http://www.majgaj.com/chroma
June 17th, 2008 at 12:47 pm
…who’s the model?
June 17th, 2008 at 1:35 pm
Her name is Siw, from Team Models in Norway.
August 18th, 2008 at 5:27 pm
For those looking for a great workflow solution for high volume green screen photography. Expecially school photographers there are several workflow solutions out there that have database capability for data import and have green screen extraction tools incorporated into the workflow solution as well. If interested check out Express Digital they have great chroma key drop out tools for high volume studio and school and group workflows.
October 29th, 2008 at 8:25 pm
bla bla