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gbkindred

Joined: 13 Dec 2005
Posts: 3
Location: Kansas City


PostPosted: Tue Dec 13, 2005 9:27 pm    Post subject: COBing people Reply with quote

I am a photoshop user and know my way around the program fairly well. I have been taking photos of students at my kids grade school. I COB each one and combine the cut out images into another larger image yeilding a complete class picture. I have been using the pen tool to create a path around the students, then selecting inverse and deleting the backgrounds. I have tried using the extrude but I don't feel it is as acurate as I can be with paths. But this is killing me it is too slow I need a way to separate the backgrounds without loosing detail around the edges of the kids. I have also tried using the magic wand and it is not much faster and sometimes can't tell the background from the foreground. I have also tried using a lime green seemless to shoot the kids on and then select the background color but it wasn't giving me the crisp edge I need. Can anyone hepl? Bythe way it takes me around 20-30 minutes per kid to do it with the pen tool.


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lasa

Joined: 08 Aug 2005
Posts: 1090
Location: Florida
PS Version: CS
OS: MS XP

PostPosted: Wed Dec 14, 2005 6:45 am    Post subject: Reply with quote

I like using the quick mask...I use a hard brush...as I go around I change the size of the brush to be able to fit into corners etc. If you make a brush mark then click the shift key and make another mark it creates a line..this helps while going around..

This gives me the quickest results. The rest of the tools work but I spend so much time cleaning them up that it drives me crazy. Do it once do it right.
Lasa
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cbadland

Joined: 19 Jan 2005
Posts: 962



PostPosted: Wed Dec 14, 2005 8:12 am    Post subject: Reply with quote

Shoot on the lime green then try using the Channel Based Mask technique to select your subject. (in short, find the channel with most contast between subject and background, Copy it, then use Levels, Dodge/Burn and paint to get pure Black and White, then load as selection to get your mask.)
From Julieanne Kost:
http://www.adobeevangelists.com/pdfs/photoshop/01_09_2002/channel_masks.pdf
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gbkindred

Joined: 13 Dec 2005
Posts: 3
Location: Kansas City


PostPosted: Wed Dec 14, 2005 9:16 am    Post subject: COBing People Reply with quote

As much as I've used Photoshop I don't get quick masks, just have found other ways to do things. Is the quick mask method as accurate as the pen tool?

Also last time I shot on the green background I noticed grenn hues reflected on the faces and white clothes. That was not ideal either.

Do either of these solutions take lest time than I am currently spending?
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cbadland

Joined: 19 Jan 2005
Posts: 962



PostPosted: Wed Dec 14, 2005 10:29 am    Post subject: Reply with quote

How about shooting on a white backdrop, then use the Green or Blues channel to make your alpha channel?


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lasa

Joined: 08 Aug 2005
Posts: 1090
Location: Florida
PS Version: CS
OS: MS XP

PostPosted: Wed Dec 14, 2005 12:41 pm    Post subject: Reply with quote

I like quick mask..and yes i think it works as well as the pentool or better on extractions involving a lot of changes in direction (people with cloth on, trees dogs..)
I use the pentool for long sweeping lines (legs..cars, balls)
masking is the same as coloring, you've got to keep in the lines.. corrections are as easy as erasing... take a look as Qmask I think it will help...I've attached a simple sample of a Qmask just before making it a selection...red and the actual extraction.

Extraction via channels is good also..
Lasa



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gbkindred

Joined: 13 Dec 2005
Posts: 3
Location: Kansas City


PostPosted: Wed Dec 14, 2005 8:43 pm    Post subject: Reply with quote

Thanks for all the tips. I'll try them. The white background has possibilities but I'm afraid without studio lights I'll get shadows on the white background and those will show up, which I can erase as long as they don't intersect the images to severely. I will give the quick mask a try too. My goal is to save time.
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cbadland

Joined: 19 Jan 2005
Posts: 962



PostPosted: Wed Dec 14, 2005 8:57 pm    Post subject: Reply with quote

Well, I'm a big fan of QuickMask. But if the photo-shoot is controlled with background and lighting, I think channel based masking can be quicker and more accurate. (shadows should easily drop-out.)
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chirpie

Joined: 14 Dec 2005
Posts: 1
Location: olathe, ks


PostPosted: Thu Dec 15, 2005 12:00 am    Post subject: Reply with quote

gbkindred wrote:
Thanks for all the tips. I'll try them. The white background has possibilities but I'm afraid without studio lights I'll get shadows on the white background and those will show up, which I can erase as long as they don't intersect the images to severely. I will give the quick mask a try too. My goal is to save time.


Well, I'm sure you have some foamcore lying around the office. ^_^ Just drag two large pieces with you, use one for the background and the other for a reflector in tandom with the bounce flash on the camera.

Even if you have some shadow creeping up on you, the quickmasking through a color channel technique detailed earlier in the thread could at least put you on the right path (oh, crappy pun alert!!!). If you wanted you could then use your pen tool technique and add the selection to your quickmask to finish it off.

Oh yeah, make sure to take the kids picture's in August, that way they have the whole summer to get tan and will show up better on that white background. :-)

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