Change background but keep shadows - help!

[baltzer]

Dear Everyone

I've been experimencing with this for quite some time now, but I can't seem to get a great result...

My "problem" is that I want to learn how to change a background in photoshop, but still keep the shadows.

The first attachment shows a model against a blank wall. Note the shadow.
The second attachment is the new background that I would love to put in.
The third attachment is an example of how I would like it to look like in the end. You know, where it looks as if she was actually in front of the decorative wallpaper, when the picture was taken.
How the h... do I do that, without it looking bad? I have tried several tutorials but can't seem to find "IT", so therefor....I need your help!
Is there any of you who know how to do this, and get a great and realistic result? And want to share?

Thank you so much in advance

[baltzer]

Sorry, the attachment generator messed up the attachments.
The first pic: girl on white background
Second pic: Wallpaper
Third pic: Girl in front of wallpaper WITH lots of shadowing going on

[Steve]

Here's a simple thing you can try.
Completely remove the background in the girl layer including the shadow.
Put the girl in front of your background.
Duplicate the girl, rename the layer shadow and with levels make it black.
You'll see specks of color, paint them black.
Blur the the layer, lower the opacity.

Move the shadow around and make sure the layer is in the right order so the shadow is behind the girl.
Use transform, add more blur if needed and adjust opacity until it looks right.

[Hoogle]

Sorry to say dude but if you want good results you will need better starting image as a once over this is what I got

Obviously I have changed her cyan colour to a red to suit the background made a selection of her using a quick select tool then turned on the background layer that is above her and with her still selected select layer mask and it will mask most of her out just touch up your mask with brushing it in and out. then turn of the red layer make a quick selection of the shadow copy it to a new layer do a levels adjustment to blacken it out and then turn the background layer of the red pattern back on with the shadow above it and adjust the layer opacity accordingly
here is my psd 1327621265289048.psd

[SeniorS]

Steve's advice is good.

Here what i would do.
1. Cut out girl and put it on wall. Use feather=2 (or 1) and contract selection for 1 pixel, that will make it look more natural.
2. Cut roughtly shadow (can include white border). Put it under or above. And set blending mode to multiplay.
3. Add mask to shadow layer and with brush paint a little at sides with slight opacity (with black) to make wall little visible.
4. Gausian blur shadow 3.3.

Here rought result, i didn't want to make good selection. But in overall it's not very complicated:

[Steve]

To me the existing shadow is not believable, it just doesn't look right.
Here's what I mean about blurring the shadow.
I'm following Hoogles lead and posting the PSD with a unadjusted shadow layer to play with.

[Hoogle]

Yeah I agree with the shadow I think it was taken with a floor light or strobe with a colour gel on it which caused harsh shadows not a flattering look especially on female models.

[Hoogle]

Nice job on the shadow though steve

[baltzer]

Thanks everyone
Yeah I know it's some bad pictures I've posted, but it's just some I found on the net to give an idea about what I meant.
I will deffinately use better pictures in my final processing, and pictures that match better.
Steve, what you've done looks great - I think I can definitely use that - and thanks for the psd file, that helps me a lot
Thanks again for the help guys. It's great that you are willing to take the time and help me with this

[Steve]

Show us what you come up with when you finish it.