poohfin

Anyone out there knows how to crop out a blue screen? I have taken digital photos with a blue screen background. But when I use photoshopto crop using the magic wand option, I only can select part of the blue, not all. Any other options? Thanks for the help!

shem

I'm guessing that your blue screen has slight variations of blue and the magic wand is only picking one them. Try Select>Similar and see if it picks up the rest of it. Keep in mind that if your photograph has a similar blue in I believe it will also then be selected. You'll then have to "unselect it". Hold down either the Alt or Ctl key while using your selection tool to selectively unselect the affected areas of your photo. Note: I don't have PS here at work and I can't remember which key..doh. Am I close guys?

Rich

vogonpoet

Hi Poohfin and welcome to the forums.

Instead of using the magic wand tool, have you tried the 'colour range' tool? This is found under the SELECT pull down menu.
It gives you the options of specifying a colour and then using a tolerance slider and the preview window, you can fine tune the amount of colour that is used to create the selection.

Also with the magic wand tool, there are options that allow you to set a tolerance also, it is just not as easy to see the selection as with the colour range tool.

You might also consider using a channel as a basis for creating a selection.

With the colour range tool, a little tip is to pre select as close as possible to the subject you are trying to isolate from the blue bg, with a standard lasso, or rectangular marquee selection. This limits the amount of data used when in the colour range tool and can make the results better.easier.

Hopefully, the blue variations are suttle enough that the colour range tool will do the job for you.

What version of PS are you using?

There is in later versions of PS the "Extract" command that might also be a good method for the problem you describe.

Lets us know how things work and if you have further questions

[righton]

vogonpoet

ya beat me to it Rich! I type too slow!

good info there from Rich too

Kalrog

Hi poohfin,

I think the reason you can't select the whole background with one-click magic wand is because you have different values of blue. The background has to be evenly lit which is a very hard thing to do.

what you might want to try is that you can select the blue background with Select -> Color Range and from the Color Range dialog box select Sampled Colors. by using the eye dropper with the + sign, you can add different values of blue to the selection. after selecting your blue values, you can switch to "quick mask" mode and detail your selection.

There are alot of ways of making selections. You can use the lasso tools or the pen tools or by switching to the quick mask mode could be other options. Whichever works fine for you.

hope this helps

OZ

Kalrog

wow!! we've all been typing at the same time?? [bustagut]

this looks funny tho.. we've all been talking about the same things..

vogonpoet

LOL too many bright minds !!!


too much info is better than none at all!

Kalrog

I guess I am the one who types the slowest! haha..

kiwi

Nah that would be me Oz I have only just got through now [bustagut]


poohfin even when they use blue screening in movies quite often even after keying the color and adjusting the mat they can still sometimes have color fringe around the object which has to be removed by using a method of different alpha channels for different areas,ie hair becomes on alpha,arm etc,then all alphas are composited together and then run as one alpha removing the fringe altogether,although I dont now if this happens with the bigger studios now


Let us know how you get on,this could be quite tricky depending on your image


Stu.

Kalrog

Here is a link if anyone is interested in blue screening

http://www.howstuffworks.com/blue-screen.htm

I think it must the be the ultimate joy to work in film industry