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Removing backgrounds from original picture

Posted: Wed, 10th Sep 2008, 3:16pm

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HeatherSlater

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I have read through the whole support forums, watched the videos, and went through the overview as to how to use Photokey and it doesn't really give clear instructions as to removing the background from you original image- also in some of the images that I have imported there are little black dots on the picture??? Any help would be greatly appreciated.
Posted: Wed, 10th Sep 2008, 11:08pm

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Arktic

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Can you post one of your original photos so we can see your blue/greenscreen set up? Also, can you post an example of an image with the 'little black dots' so that we can try and figure out what the issue is?

Cheers,
Arktic.
Posted: Wed, 10th Sep 2008, 11:30pm

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HeatherSlater

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I didn't set up a bluegreen screen-
For some reason - now the photos that I'm importing doesn't have the little black dots...

Not to be stupid but I don't know how to post any photos...
Posted: Thu, 11th Sep 2008, 12:11am

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Axeman

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If you have an ordinary photo, without a greenscreen, you can't remove the background with Photokey. It is specifically designed for keying out chroma backgrounds. To remove the background from an ordinary photo, you will need an image editor along the lines f Photoshop or GIMP, and you'll have to do some tedious masking to remove the portions you don't want.

The black dots are probably bits of the photo removed by the software when it tried to pull an auto key.
Posted: Thu, 11th Sep 2008, 1:43am

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HeatherSlater

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What exactly do you mean as far as greenscreen?
I thought that anyone could use this program to remove backgrounds from pics and replace them with new backgrounds???? I wouldn't have purchased the software if I knew you couldn't.... What about the example where the guys sitting outside in a chair- they changed his background...
If it's impossible to do what I'm looking for I'll just get my money back...
Posted: Thu, 11th Sep 2008, 4:27am

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Axeman

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I'm not exactly sure which picture you are referring to, but the demo video clearly shows photographs being taken in front of a greenscreen, and then various backgrounds replacing the greenscreen. The blurb underneath, about the software, says, "Discover a new world of creative possibilities and introduce your clients to the magic of greenscreen and bluescreen photography." Sorry for any confusion, but the software is designed for a very specific task, which is working with greenscreen or bluescreen photographs.

Once you have taken your pictures in front of a greenscreen, you can quickly and easily replace the greenscreen with any background of any location you choose. Greenscreens can be had for cheap these days, and aren't very difficult to work with.
Posted: Fri, 12th Sep 2008, 3:25am

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HeatherSlater

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so basically the bluescreen and greenscreen term is a backdrop?
Posted: Fri, 12th Sep 2008, 6:16am

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Axeman

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Correct. A key, in the sense of Photokey, is a process whereby a specific color is removed from an image. By using a green backdrop when you shoot the image, it enables you to easily remove the backdrop, thus leaving only the subject of the photo, which can then be placed in front of whatever background you desire.
Posted: Fri, 12th Sep 2008, 3:22pm

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HeatherSlater

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Do you have any suggestions as to which product to purchase?

Green Chroma-Key Plastic Background 54" x 108" (1.37m x 2.75m)

Inexpensive, matte finish to reduce reflection. Light weight and low cost shipping anywhere in the world

OR

Chromakey Green Muslin Backdrop Large 10' X 12'

100% Pure Cotton, Completely Seamless, Fully Stitched

Color ? Green or Blue for Photokey
Posted: Fri, 12th Sep 2008, 3:27pm

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Simon K Jones

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I'd go for muslin over plastic as it's likely to have better texture and light reflecting properties for this kind of work. Plastic could potentially crease quite badly, too, whereas any creases in muslin can always be ironed out.

Size depends on what kind of photography you plan on doing. Same goes for colour - the important thing is for your subjects to not have any of the colour. So if you're planning on shooting lots of green things, get a blue screen, and vice versa.
Posted: Fri, 12th Sep 2008, 3:30pm

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HeatherSlater

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Thanks for your input Tarn- also am I going to need special lighting or no?
Posted: Fri, 12th Sep 2008, 3:35pm

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Simon K Jones

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You don't need special lighting as such, but you do need good lighting. Green/bluescreen photography is one of those things that can be as easy or as difficult as you make it - the better your lighting, the easier and better your results will be when you get to the compositing stage.

Here's a few general tips:

• Your greenscreen can be made from cloth, paint or paper. Each have their benefits and problems. Cloth is excellent if the greenscreen needs to be moved regularly. Paint is ideal if you have a dedicated, permanent studio space. Paper is a good alternative if you do not have the liberty of painting the studio area, but can prove difficult to move if necessary.

• No matter which media you choose to construct your greenscreen, you must ensure that it is of a uniform colour, is flat and untextured and has a matte finish.

• Check that the greenscreen is not shiny or overly reflective.

• Be careful to avoid creases, as these can cause problems.

• Try to construct it in an area large enough to light the screen and your subject separately. This will enable you to light your subject dramatically, whilst lighting the greenscreen in a flat and uniform manner. It is important to not cast any shadows on the greenscreen itself (unless you deliberately want to, of course).

* Put as much distance between your subject and the greenscreen as possible. This will help avoid unwanted shadows and will make your subject 'pop out' of the background more.
Posted: Fri, 12th Sep 2008, 3:39pm

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Axeman

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Green and blue are the colors typically used because neither is typically found in skin tones, making it easier to photograph people for keying.

Plastic is probably going to be a lot cheaper than muslin, so it might be good to get at first to do some experiments with, but muslin will generaly perform better and last longer, as Tarn mentioned.

As to lighting, you don't really need any special lighting, though some sort of lighting is good. If you can shoot outside, a cloudy day makes for quite good greenscreen lighting. If you are shooting inside, you want to keep the lighting as even as possible on the greenscreen, so the color is all the same. Another tip that will be helpful is to not get your subject too close to the greenscreen. I find that 5 or 6 feet between the subject and the backdrop works well. If you get too close, the green tones from the backdrop will reflect onto the edges of your subject, and make it difficult to get good clean edges when you key out the green.
Posted: Fri, 12th Sep 2008, 7:20pm

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HeatherSlater

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Thanks alot for all your help- I'll wait till the screen comes and hopefully I won't have anymore problems- however I still don't understand how come the green screen or blue screen can be removed but any other background can't???
Posted: Fri, 12th Sep 2008, 8:32pm

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Axeman

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The software has no way of knowing what the content of an image is. It can't tell if any given pixel is part of the foreground you want to keep or a background element you want to remove; all it can see is the color data, not the actual picture. So, if you use one specific color for the background, such as green, you can easily tell the software to find that color anywhere it appears in the image, and remove it. All it is doing is removing a specific color, based on the settings the user provides.
Posted: Sat, 13th Sep 2008, 4:56am

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HeatherSlater

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Got cha-

Thanks for all your input and thanks so much for your support-
Posted: Mon, 15th Sep 2008, 8:14am

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Simon K Jones

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Yeah, the problem is that a computer doesn't 'see' the image in the same way we do. It doesn't see a person, and a background. It just sees a cluster of different coloured pixels. When using a screen of uniform colour, as Axeman says, you can just tell it to remove that particular colour.
Posted: Mon, 10th Nov 2008, 3:02pm

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sebg22

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Hi;
I'm using the greenscreen ... problem is that my subject has got green eyes ... How may I avoid the eyes of my subject becoming the same as the new background ???
Posted: Mon, 10th Nov 2008, 3:07pm

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Simon K Jones

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Currently there isn't a way to avoid this, other than using a bluescreen.