Infinite White Background Question

Started Aug 3, 2012 | Discussions
TotalNeophyte
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Infinite White Background Question
Aug 3, 2012

Say you have found the perfect exposure for your subject (say by using f/8, ISO400, 1/60th); you are absolutely content with the subject and you don't want to change the camera settings, but the background isn't pure white. It is close and you have tried to adjust it in photoshop, but it makes the subject look out of place with respect to the background. Also, there's nothing one can do with how close the lights are (they are already as close as they can be).

Would one's last recourse be adding more lighting to the background?

I'm using a pure white background paper and I have 800 watts on it and they're close.

What would you do? Am I missing something?

Lawrence Keeney
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Re: Infinite White Background Question
In reply to TotalNeophyte, Aug 3, 2012

Are you lighting the background with a separate light from which you are lighting your subject?

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TotalNeophyte
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Re: Infinite White Background Question
In reply to Lawrence Keeney, Aug 3, 2012

Yes, indeed.

2400w through softboxes on the subject about 5 feet from subject and 2000w of non-diffused light about 3-5 feet from background (angled).

Edit: The comment about there being 800w on the background was way off.

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TiagoReil
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Re: Infinite White Background Question
In reply to TotalNeophyte, Aug 3, 2012

You need to add more light. But it is a balancing act. Generally you add 2 or 3 stops more of light, so from f8, you should have f16 at least on the background.

Too much light will bounce and hit the back of the model. This could be good or bad. Generally bad, cause the model melts with the background, but it may add a nice rim in some cases.IT may also add flair, and low contrast.

Some days ago I read this post. It looks like you will always have to add some Photoshop

http://neilvn.com/tangents/2012/07/31/high-key-studio-lighting-portraits-model-ulorin-vex/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+tangentsblog+%28Neilvn.com+-+tangents%29&utm_content=Google+Reader

TotalNeophyte wrote:

Yes, indeed.

2400w through softboxes on the subject about 5 feet from subject and 2000w of non-diffused light about 3-5 feet from background (angled).

Edit: The comment about there being 800w on the background was way off.

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Barrie Davis
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Re: Infinite White Background Question
In reply to TiagoReil, Aug 3, 2012

TiagoReil wrote:

You need to add more light. But it is a balancing act. Generally you add 2 or 3 stops more of light, so from f8, you should have f16 at least on the background.

That is bad advice. You should not use so much. It should be only so much as to clean up the background. Half a stop over the subject brightness is plenty, but it does need to be even if the background is required white all over.

Using more than 1/2 stop excess risks flaring around the outside of the subject, especiaqlly when the background is close. Also large amounts of non-image-forming light passing through the lens from overlit backgrounds will cause flare over the image as a WHOLE, desaturating the subject even AWAY from its edges.

In a nutshell, add between 1/3rd and 1/2 stop, then STOP!
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Sailor Blue
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Re: Infinite White Background Question
In reply to TotalNeophyte, Aug 4, 2012

Wow, that's a huge amount of power for only f/8. The subject must be blind for hours afterward.

This perfectly illustrates the reason why using studio strobes for animate subjects is preferable to using continuous lighting. I can get f/8 with 150-200Ws of power in a 40"x40" softbox at 6' from the subject.

With your lighting setup you have several options.

You can move the subject lights further from the subject and decrease the shutter speed to maintain the same aperture, thus effectively increasing the background exposure, but this reduces the softness of the subject lighting.

You can adjust the background lighting so that it forms a pure white halo around the subject for your current subject lighting then paint in white beyond the halo during post processing. I have even painted in white when some of the area beyond the white background or a softbox wound up in the image.

If the background is close to white you can adjust the Exposure in Adobe Camera Raw or Lightroom 4 until the background is pure white then bring back the highlights with the adjustment tools. Again, you can always paint in more exposure in the background area away from the subject so just a halo of pure white around the subject is necessary.

Let me emphasize what Barrie Davis said. Whatever you do, don't overexpose your background by more than 1 stop. If you do you will likely get the background light bleeding around the subject's edges. Keep your model at least 6' from the background to minimize this problem. A bright white background can also cause broad light source lens flare with a resulting loss of subject contrast.

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itsDing
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Re: Infinite White Background Question
In reply to Sailor Blue, Aug 4, 2012

l am a working photographer and learned ages ago that to over light a background by 2 stops is rubbish. Digital sensors do not like it, who needs lumps of light reflected from the background on the sides of faces? All you need to do is brighten the background, the same exposure as the subject works ok providing you have an even spread. A third over can be fine. if you want a rim. Fall off of light is important. l meter the reflected light from the background to where the subject will be and make sure it is under the subject exposure. Most of my work is childrens pictures using a posing table, l light the background (white roller blind) from behind with a light firing into an umbrella.

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GHwell
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Re: In PS
In reply to TotalNeophyte, Aug 4, 2012

there is no reason you should not be able to get a white BG in PS
Many ways to get it white

all you need is pure white directly behind the subject then ad a layer and paint white
try go to select white and remove all color

select white with the wand and do a copy paste to new layer set to screen or paint white on that layer.

try dodge set to high lights you can go right over a darker color with no effect to that color

I never try for pure white beyond 1 in aroud the subject It is faster to do a PS touch up than meter lights

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GHwell
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Re: post a shot
In reply to TotalNeophyte, Aug 4, 2012

be glad to do the touch up and explain how

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TotalNeophyte
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Re: post a shot
In reply to GHwell, Aug 5, 2012

Thanks for the offer!

So, I know how to get pure white in PS - but when I do, there is usually a very slight halo around the entire subject. If I adjust exposure, I lose resolution. I was playing around with the highlights and that seems like a good option.

Let me just say, continuous lights are a real pisser. I have gotten to the point where I really like the exposure of the subject, but I can't get a good exposure on the subject and pure white. You should have seen my f8-1/125th-ISO100, it's a joke. I have to use ISO100, but I'm not a fan of the noise (even when I adjust it in lightroom).

I do video with the subjects, too, so I only went with continuous.

I tried painting the background and then using the history/memory brush (sorry, I forgot the name) around the subject, but it still has that halo - once I do that.

I could get pure white just behind the subject, but I'd have to move the backdrop lights in frame. This would be okay if I were only doing photos, but it's problematic for my videos.

So, what would you do? Haha

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GHwell
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Re: halo or flare
In reply to TotalNeophyte, Aug 5, 2012

If you mean a hase or flare then you have the subject too close to the background.

2/3 to 1 stop above what ever you are shooting the subject at should produce a white background. Please post a shot with the halo

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GHwell
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Re: An example
In reply to TotalNeophyte, Aug 5, 2012

Orginal
dub layer set to multiply and selected gray background
reason for going to multiply was I got a cleaner selection
Chnaged mode back to normal before copyiing
copied and pasted selection set layer to screen
dubbed layer again.

used dodge brush set to highlights on orginal layer to clean up gray around hair.
http://www.pbase.com/image/145196303

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TotalNeophyte
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Re: halo or flare
In reply to GHwell, Aug 5, 2012

I'm sorry, I meant a halo of the original background color. Is there any way to truly alter every pixel that is separate from the subject (other than by zooming in and doing it pixel by pixel)?

Also, is there an effect I should be using to make the subject look like they "belong" in front of the backdrop? I've seen some professional images where it actually looks like they were in front of that backdrop - when I knew they weren't. What kinds of effects are they using? I assume they are just taking an image in front of a pure white and then adding in the background later. Well, how do they get it like it's seamless? Is it something in the lighting or in post?

Sorry for the 20 questions...

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TotalNeophyte
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Re: halo or flare
In reply to TotalNeophyte, Aug 5, 2012

Thanks for that image; that's exactly what I'm talking about. The right image looks like she was actually photographed in front of a pure white background.

So, all you did was:

1. Duplicate the layer and set it to multiply
2. Select the background and set the layer back to normal
3. Selected the original and pasted the background
4. Here you used the paint bucket and painted it white?

5. I'm not exactly sure how the dodge worked in here, I'm not too familiar with it

Thanks

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unknown member
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Re: halo or flare
In reply to TotalNeophyte, Aug 5, 2012

TotalNeophyte wrote:

Is there any way to truly alter every pixel that is separate from the subject (other than by zooming in and doing it pixel by pixel)?

Yes. Select the background and open a curves (or levels) adjustment layer. That will create a mask that protects the subject. Use the white dropper to make the background pure white.

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itsDing
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Re: An example
In reply to GHwell, Aug 5, 2012

Whats all this layer stuff! Just open levels and click the white eye dropper on the whitish background, it will go white. Simple eh! Use the shadows slider if you want to darken the image a little afterwards.

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GHwell
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Re: An example
In reply to itsDing, Aug 5, 2012

That is why you are effecting the image and the lighter or white areas in it

You said you wanted to change th background not the image. That is your problem in a nut shell.

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GHwell
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Re: close
In reply to TotalNeophyte, Aug 5, 2012

by copying just the back ground asdn setting the layer to screen it lighten the background on that layer only . To get even whiter I did a second layer

I went back to the orginal layer. The screen modes are partially transparent. I set the dodge tool to highlights on the top menu bar. by going around the ecges of the hair it whitened the gray areas left in the fly away hair without changing anything else. This does not always work. The other poster was working in a mask selection when he used the eye dropper not just on the backgorund. That is why he did not effect the lighter tones in the picture.

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GHwell
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Re: Peano version
In reply to TotalNeophyte, Aug 5, 2012

here is a screen shot of what he did. get the same results just a different way of doing it
http://www.pbase.com/image/145201715

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Barrie Davis
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Re: An example
In reply to itsDing, Aug 5, 2012

itsDing wrote:

Whats all this layer stuff! Just open levels and click the white eye dropper on the whitish background, it will go white. Simple eh! Use the shadows slider if you want to darken the image a little afterwards.

That's how NOT to do it!

If a white background is required it needs separate treatment. Either separate slightly brighter lighting that is otherwise kept OFF the subject, or separate post processing, that is similarly kept OFF the subject.

Myself, I think fully white featureless backgrounds are a fad that always was intensely boring and is now well passed its sell-by date... (but hey, that is a different matter.)

Even this text panel isn't full white, y'know..[?] Compare it with the white arrow cursor to see..
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