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Extraction and new background - new trick

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  #1  
Old 09-14-2005, 12:28 AM
leuallen leuallen is offline
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Extraction and new background - new trick

I've never had much luck with extractions. I've tried everything - tutorials here, Russel Brown's tricks, and on and on.

This picture is sort of a bench mark for me. It is my trial image because it is difficult. I figured that when I mastered it, that I would be confident to tackle almost any extraction. I've tried numberous variations on this image for the last six months, all with poor results.

Well, I had an 'Ah ha' moment this afternoon. It was an idea of a different way to approach the problem. It is based on the standard way of extracting using a channel and dodging and burning. There is a trick I used, I've never seen anyone do this, that gave me the control I needed. It's late now and I'm tired so I won't get into it now. Tomorrow I''ll post what I did.

The final image used a scenic background but I tried the extraction method with a white, a 50% gray, and a black background, all with good results. The extractions were a little different in each case: what worked good for white looked bad with black and vice versa.

By the way my new technique is not difficult or even radical, its kind of obvious in a way when you think about it.

Until later

Larry
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File Type: jpg Cara23-original.jpg (97.7 KB, 282 views)
File Type: jpg Cara23-finished.jpg (91.1 KB, 328 views)
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  #2  
Old 09-14-2005, 09:07 AM
superfrasky superfrasky is offline
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another option is knockout plugin. Is faster and the result is good.
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  #3  
Old 09-14-2005, 10:53 AM
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Gary Richardson Gary Richardson is offline
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Hi Larry,

Can't see where you'd have problems in extracting this. On a plain background with high contrast, she's an ideal candidate for creating a mask.

Have put her on another plain background of a different colour, as this enables all fine hair detail to be seen.

Have just used usual masking techniques.
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File Type: jpg Cara23-original copy.jpg (95.6 KB, 174 views)
File Type: jpg Layers.jpg (12.6 KB, 150 views)
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  #4  
Old 09-14-2005, 01:23 PM
maureeno maureeno is offline
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Quote:
Originally Posted by Gary Richardson
Hi Larry,

Can't see where you'd have problems in extracting this. On a plain background with high contrast, she's an ideal candidate for creating a mask.

Have put her on another plain background of a different colour, as this enables all fine hair detail to be seen.

Have just used usual masking techniques.

This is a very dumb question, Gary, but I must ask it: Whilst extracting via a mask, do I paint on the mask with the brush and paint all the fine details of the hair?

I ask because I use this in PhotoImpact and it works, but it's tedious. Is it easier in PS6 (my version)?

Maureen
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  #5  
Old 09-14-2005, 07:12 PM
leuallen leuallen is offline
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Ok, here is what I did. Using a channel as the basis for the mask.

1. Color correct for the background, which was originally white. If this is not done, the highlights on the hair from the light reflected back from the background will have a cast. This will contrast with a background of a different color and look unnatural. If the background is not neutral, the color cast will have to be handled later, not easy. This is usually a tedious process, so if you can, make the correction globally, as done here, to save work.

There are two problem type of background mistakes that the photographer has control over when shooting. When using a green background (Cromakey sp?), the background is too close to the subject. This reflects a green tinge on the hair. The background has to be back as far as possible to reduce the effect. The other occurs with a white background. The photographer strives to blow the background out to pure white. He overlights it and the background is too close resulting in too much light coming through the hair. This gives an unnatural glow to the hair when placed on a mid tone background and has to be toned down. If the photographer uses just enough light to give white and uses as much backgroud distance as possible, this problem does not exist.

Attachment 1 shows the original and color corrected file. Note that the color correction is not for the subject but for the background. If the subject color is off, its ok, it can be corrected latter.

2. Find a channel which has as much contrast between the hair and background as is possible. One trick is to investigate channels from other color spaces. Make a duplicate image and change the color space to CMYK or Lab. Check the channel in each of these spaces. If one is better than what you have in your orginal file, copy it, create a new channel in your file, and paste the good channel into your new channel.

Lab may be a good canditate in some circumstances where the object and background have similar colors because Lab seperates the color from the brightness.

I used the original green channel. There is not really much difference between them. I created a new channel and copy/pasted the green channel into it.

3. On the copy of the green channel I painted with black the interior of the object close to the objects outlines. No need to be too careful here. Then I painted with white the background up to the object outlines being careful not to paint over any hair.

The channel was inverted and cleaned up. What appears black is often not and becomes very evident when the invert is done.

Attachment 2 shows the original green channel and the inverted rough mask.

4. Now here is the trick and if you do this why didn't you tell me! On all of the videos and tutorials I've seen, dodging and burning is done on the channel in BW, completed, and then inserted as a mask then tweaked. In Russel Brown's video, he says to burn at 50% set to shadows and sweep over the edges between the subject and background. And the same with dodge set to highlights. He makes it look easy. I tried and tried and each time I brought my channel in as a mask it looked like crap. Too little, too much, but never correct.

So what I do is use the mask with that ragged looking processed channel shown in attachment 2. Now when I look at it, it looks like crap but I expected it to.

The second point to the trick is that you have to use the final background you want at this stage, not at the end of the process. What you are going to see is a very rough extraction over the final background. Using the final background is important because I did tests and the best mask for a black, gray, or white backgrounds are all differnet. It's not one size fits all.

5. Activate the mask, the "dot" icon will be in the second column. You can see both the image and the background, but anything done will effect the mask only.

So try Levels or Curves or maybe Apply image, whatever you are comfortable with. I'll use Levels. The Levels dialog is visible and as you adjust the sliders you can see the effect on the image and background. Adjust so that you do not remove too much fine hair and the 'halo' disappears as much as posssible. It will not look too bad at this point but there is cleanup to do.

Now use the dodge and burn tools. Set dodge to highlight and about 20%, burn to shadows and also 20%. Now as Russel says, sweep over the transitional areas, alternating between dodge and burn, until the areas blend. Only now you can see the effect of each stroke and if no good, undo and retry.

It helps to occasionly check the mask itself. If you click on the mask icon while holding down the Alt key, the mask becomes visible. It's a toggle, so do the same thing to get back to the image.

6. When satisfied with the extraction you may Gaussian blur the mask. Just select the filter and blur. You will see the effect on the final image.

Attachment 3 shows the final result

Larry
Attached Images
File Type: jpg Cara---Original-and-Color-C.jpg (97.2 KB, 161 views)
File Type: jpg Cara---Green-Channel-and-Ma.jpg (96.8 KB, 210 views)
File Type: jpg Cara---final-result.jpg (96.7 KB, 180 views)
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  #6  
Old 09-14-2005, 07:44 PM
leuallen leuallen is offline
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Maureen,

In my process I used soft bushes of various sizes and low opacity. I did not paint in any individual hairs of clumps of hair or give any of those areas special up close detail work. I used broad sweeping strokes to start off, with the full image visible. Then I went to a smaller brush and zoomed the image and found little areas that need attention, but still with generally broad strokes. For example, on the inside of the hair my rough mask showed lines of demarcation at the edges where I had originally painted with black. I blended them by burrning the mask to gradually fade out toward the hairs edge with a soft brush. It was pretty quick and not a precise operation. The final mask at the hairs edges is fairly translucent or gray, for a short zone at the edges. This is what gives the effect of the background light shinning through the hair. If it were just a hard transition between black and white, then this effect is lost. The hair then looks very hard and ragged at the edges. That is the effect I used to get before I figured out what I was doing wrong. I was suprised after I had done a good extraction with the method I explained above, and compared the mask to what I used to do. It was much softer around the hair and had much more gray. I interpreted, wrongly, from the tutorials I studied, that the edges should be hard with little gray. Oh, how labored to kill the gray and thus the mask.

It is too difficult, expecially with a mouse, to try and trace over hairs and do fine work like that on the hair. It often does not turn out well, at least in my case, others may have better skill.

Larry
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  #7  
Old 09-14-2005, 08:04 PM
leuallen leuallen is offline
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Gary,

It's not as easy as it looks. Your image still has traces of the background showing through. I'm sure that you, with a little more care, could have eliminated it. But in so doing you would probably loose a lot of the fine hair. I'm also sure that someone with more experience than I would know just how the mask should look for a good result. I could not grasp that until I found the process described above that let me see the masking results in real time.

I wanted to be able to get a very clean background and keep as much fine hair as is possible. That's the part that's not easy.

Larry
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  #8  
Old 09-15-2005, 03:49 AM
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Gary Richardson Gary Richardson is offline
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Sorry Larry, can't see any traces of background on my rendition. The new background I placed it on is not totally monotone, which may have given you that idea.

Didn't say it was easy, just that the girl was an ideal candidate for creating a mask, and couldn't see where you'd have any real difficulties.

Like your method, a bit involved, but good results (you've missed out some of the very fine hairs at the top of her head).

Maureen, I do practically no painting whilst creating a mask. In this case took the green channel (if I remember right) adjusted a little with levels, then burned and dodged to increase contrast. Did use a black brush to black out light areas of woman's face, but not for any fine detail.

When you've applied this mask to the image, it can be refined slightly, by clicking on the mask, then applying levels to it. Adjust centre slider for effect.

Also if you can't see some of the finer hairs, try painting along edge of mask with a soft white brush set to about 1-2% Opacity.


Gary.

Last edited by Gary Richardson; 09-15-2005 at 04:07 AM.
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  #9  
Old 09-16-2005, 02:42 PM
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Cameraken Cameraken is offline
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Larry

Thanks for the method. It is basically what I’ve always done but in a more sensible order. In your example picture I can’t see much difference in the results but I can think of other pictures where your method would have been useful.

I stumbled upon this today

http://retouchpro.com/tutorials/?m=show&id=132

I think it may be worth you reading it.

I had a quick play and made the attached mask with NO dodging or burning or levels.
This is straight from the picture using only a gradient.

Ken
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File Type: jpg Ken_Mask_Cara23-original.jpg (73.1 KB, 98 views)
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  #10  
Old 09-16-2005, 06:36 PM
leuallen leuallen is offline
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Thanks Ken,

Its funny, I was playing with Gradient Masks yesterday and today and that use did not occur to me.

Still have to go throught burn and dodge routine as the mask you show is not clean enough as is. It looks like a good starting point.

Larry
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