White background

chez1980

chez1980

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Hi I mainly work in portraits with natural light but I suffer with grey back grounds instead of white!

How can I make them white again in cs5?
Is it masking or layer adjustments?
Can anyone give me step by step help, spent hours on this but not sure what I'm doing x
 
chez1980 said:
Hi I mainly work in portraits with natural light but I suffer with grey back grounds instead of white!

How can I make them white again in cs5?
Is it masking or layer adjustments?
Can anyone give me step by step help, spent hours on this but not sure what I'm doing x
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If you want a white background you need to light it, not just work naturally
 
The dodge tool may do the trick, or select just the background and ajust levels.
As Hugh says ideally light the background separately but thats a bit tricky if your working only with natural light.
 
what backgrounds do you work with is it like a proper portrait where you have a white background or is it like a wall or doorway ect
 
I prefer natural lighting if I'm honest & I have a vinyl white backdrop!

I've been told I can use adjustment layer & levels or mask it but I don't fully understand x
 
adjust it so it brightens it up then apply a mask which will dull it all back down then if you use a white mask select the black colour on the paint brush and paint to show the adjustment layer through
 
you can selectively increase just the whites in photoshop, and mask any areas, using a layer mask you don't want to apply this to. It'll make teeth and eyes look better too. But you will struggle to get a white background, using just natural light.
 
chez1980 said:
I prefer natural lighting if I'm honest & I have a vinyl white backdrop!

I've been told I can use adjustment layer & levels or mask it but I don't fully understand x
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You can still use natural light on the subject but the backdrop needs to be about 2 stops lighter. You can fiddle around in photoshop for hours if your editing a bunch and get an acceptable results but make your life easier and buy some flashguns.
 
boyfalldown said:
that about 1 2/3rd stops to much on digital and you'll struggle with wrap.
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0.3 stop lighter? If you shooting the subject in natural light (presumably window light) a 0.3 of a stop wouldn't even cover the light difference of the white background near the window and furthest from the window. By your reckoning, if you exposed perfectly for the subject then added 0.3 + exposure comp in camera the background would be total white. Its just not going to happen.
 
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The problem working with available light and a white background is A. getting it even across the background and B. trying to ballance it between the background and subject, you could try lots of reflectors on the background to even it out, and maybe shading the subject slightly, but I suspect your going to end up cutting out or tweeking the background one way or another.
 
rjbell said:
0.3 stop lighter? If you shooting the subject in natural light (presumably window light) a 0.3 of a stop wouldn't even cover the light difference of the white background near the window and furthest from the window. By your reckoning, if you exposed perfectly for the subject then added 0.3 + exposure comp in camera the background would be total white. Its just not going to happen.
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yeah - right. Cause thats what I said ;)

Have a proper search, theres rather a good set of photos in the lighting forum that shows exactly what happens if you over expose the background by 2 stops. You need a 1/3rd of a stop difference for a white background. Thats all. Maybe you'd share your results with 2 stop difference.

and heres one of many references for you http://www.talkphotography.co.uk/forums/showpost.php?p=1737215&postcount=3. There's lots more
 
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boyfalldown said:
yeah - right. Cause thats what I said ;)

Have a proper search, theres rather a good set of photos in the lighting forum that shows exactly what happens if you over expose the background by 2 stops. You need a 1/3rd of a stop difference for a white background. Thats all. Maybe you'd share your results with 2 stop difference.

and heres one of many references for you http://www.talkphotography.co.uk/forums/showpost.php?p=1737215&postcount=3. There's lots more
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Well that is what your saying isn't it? If you overexposed a correctly exposed subject by a 0.3 of a stop with exposure comp the white background would be pure white?
 
rjbell said:
Well that is what your saying isn't it? If you overexposed a correctly exposed subject by a 0.3 of a stop with exposure comp the white background would be pure white?
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no its not what I'm saying at all.Reading what I'm writing is good :thumbs: There needs to be a difference of a 1/3rd of a stop between the subject and the background. Where does exposure comp come into that?. Its the differential thats important.

Seeing as you won't look. Heres the thread I mentioned before if you over expose and throw too much light on the background.

http://www.talkphotography.co.uk/forums/showthread.php?t=322681
 
No i'm reading the thread where it's saying 2 stops can be to much and can cause light spill. I know this can be a problem in smaller rooms, i'm arguing that 1/3rd is not enough to create a white background that's well within the dynamic range of a sensor.
 
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rjbell said:
No i'm reading the thread where it's saying 2 stops can be to much and can cause light spill. I know this can be a problem in smaller rooms, i'm arguing that 1/3rd is not enough to create a white background that's well within the dynamic range of a sensor.
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so where does any exposure comp come into this? 1/3 stop differential certainly is more then plenty. Try it and see ;)
 
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The exposure comp comes into as i was trying to explain by your calculations that a 1/3rd of a stop difference between a subject and background is enough to blow out a background. If you exposed for the subject and had no lighting on the backdrop you could then overexposed a 1/3 of a stop using the compensation to give you the 1/3 of a stop you wanted to blow out the background. By now the subject is obviously over exposed but the white background wouldn't be blown out.
 
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rjbell said:
The exposure comp comes into as i was trying to explain by your calculations that a 1/3rd of a stop difference between a subject and background is enough to blow out a background. If you exposed for the subject and had no lighting on the backdrop you could then overexposed a 1/3 of a stop using the compensation to give you the 1/3 of a stop you wanted to blow out the background. By now the subject is obviously over exposed but the white background wouldn't be blown out.
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as I keep explaining to you its the differential thats important. Exposure comp doesn't come into it. Using your somewhat flawed logic then a 2 stop difference probably wouldn't be blown either.

Try it and see. Seriously. Then post an example or two.
 
I will have to take your word for it i'm off to the museum!:)
 
The temptation is to blow the background out, but white only needs to be white, half a stop or ten stops doesn't make a difference to the white part, it's the amount of surplus light reflected back at the subject thats the problem if you have too much.
Two stops difference is a lot, especially in a small home studio.
 
If you want high key with a white back ground...

a good a place to any to start is getting your lighting right, try something like a 2 to 1 ratio, eg set the background to f16 and expose the subject to f8....from there i'd experiment till i found something that suits.
 
rjbell said:
You can still use natural light on the subject but the backdrop needs to be about 2 stops lighter. You can fiddle around in photoshop for hours if your editing a bunch and get an acceptable results but make your life easier and buy some flashguns.
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+1

If you shoot a white BG using only natural light it will be grey. Unless you overexpose your subject by a stop or more, which I'm guessing you don't want.

You can of course do it all post, but this sounds like an awful lot of unnecessary work IMHO.

Use additional lighting to blow out the background whilst you shoot using natural light on the subject, or perhaps consider changing to a black background which doesn't need any extra lighting.
 
Thanks, I'm now torn between buying a flash or a trigger for my studio flash?

Cheryl
 
The easiest way I have found is to mask eyes, teethhhhh and anything grey on your subject, once that is done simply Image-Adjust-Replace Colour and push the Lightness slider until it changes to white, use the +sampler to add bits it missed.

The only downside is it sometimes obliterates fine hair on the subject but if you copy the hair first then paste it back in place you cant tweak that seperately.
 
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