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Tutorial: Perfect and Easy Compositing!

April 2, 2009

The problem: cutting out a partially transparent image

My friend Laleeta requested help with how to cut out partially transparent items from their background, quickly and easily, in order to composite the image onto a different background in Photoshop.

There are a number of ways to go about this. I recently had to deal with this very issue when I was making the vendor ads with a partially transparent skirt, and I found one way (limited to SL) that works very well, very quickly!

There are a few steps to this tutorial, and I went into extreme detail so that any skill level of Photoshopper can use this trick, but overall it’s very simple and basic. This should also work for gimp but I’m not sure of the exact commands on gimp. Any gimp users that can provide gimp translations, give a holler in the comments and I will add them to the post.

Royally Alicia

Here’s a finished example, one of my vendor ads, the original inspiration behind figuring out this work flow. Particularly vexing for me was that I wanted to add a shadow in Photoshop, so I needed a clean composite. I also wanted to add more shading/shadow to the background image but didn’t want any of that to be on the untouched product image.

The detailed steps with pictures after the cut –>

First, we start in Second Life…

1. For taking the picture in SL, it’s best to use the final background you will be using in Photoshop, OR at least the major/main color of the background you plan to use. This does not have to be perfectly lined up by any means, it’s only meant to help prevent “matting” or “halo” problems (example: cutting out of a white background can make the cutout have a tiny white edge). This is especially true if 1. you are trying to cut out partially transparent areas 2. you have anti-aliasing turned on in your viewer.

So either upload the background image or choose the best overall/mid-tone color of your planned background. Again, you are doing this to make sure that the tiny wee edge that is left over is of the generally correct color for the final composite. If you don’t know the color of the final background, going with a mid gray is a safe-ish bet. Or if you are going to put a dark shadow around the avatar then going with a darker color should work. This is one of those steps that makes more sense when you’ve done it a few times. When I did my vendor, I simply used the background I was going to use as final in Photoshop. I could have also used mid/darkish green/grayish color and it would have worked fine.

2. Rez a prim and apply your background image or background color. Set the prim to FULL BRIGHT.

3. Get on your pose stand and line up the shot with your camera, adjust the background prim as needed to cover all edges of the avatar and the attachments. Note that here I have put my pose stand and the background prim within my all-white full-bright photosphere as well. (which is simply a 10m x 10m x 10m hollowed sphere with a lil dimple added, set to full bright white.) Here’s a shot of my photo area, set up:

photosphere

And here’s my shot lined up. Notice the background covers the avatar and all attachments:

colorpicture2

4. IF THE ITEM IS FLEXI…it’s best to take the following step so that things line up perfectly. When the flexi is in the place you want it, it’s time to turn flexi off to assure that the flexi does not move. We’re going to be taking 2 pictures here, so it’s important that they line up exactly. Turn flexi off by either the advanced menu (Advanced>  Rendering > Features >Flexible Objects)….or the keyboard shortcut (control/command + option + F9).

5. Ok, now to take the picture! Make sure you have your windlight setting you want for the picture, then snap away. If you made a custom windlight setting, you might want to save it as we’ll be changing the windlight setting in a moment!

6. Very important: don’t move your camera yet!! Not until we take picture #2, the silhouette picture.

7. Now select the background prim and change it to 100% white, with full bright still on.

8. Now change your windlight to the settings in the image below. Be sure to save it for future uses!

silhouettewindlight

9. Now take another picture with this cool black and white look, which will end up being our mask in photoshop. (A mask is a black and white image that will tell Photoshop what parts to keep and what parts to make see through.) My silhouette image below:

silhouettepicture1

10. Now you’re done in SL, you can turn your windlight back to a normal one and turn flexi back on if you turned that off, and its safe to move your camera now 🙂

11. Off to Photoshop!

12. Open up both images in Photoshop and first select the black and white one. We’re going to drag and drop this image onto the color image, but we’ll use a nice Photoshop trick so that it lines up exactly. The trick is: with the Move Tool (v) selected, drag the black and white image onto the color image, but BEFORE LETTING GO OF THE MOUSE BUTTON to drop it, hold down the shift key as you do so and it will drop it lined up exactly on top of the second image. You can now close the black and white only image; now that it’s in the file with the other we don’t need that file open anymore.

13. Now you have 2 layers in the other file, with the black and white image on top. Double click the “background” layer so it becomes editable.

14. Now, take a look at the black and white image on top. For the most part, it should be perfect. But full bright things worn by the avatar can mess up this method***, so we will fix any of those now. Also, some images sometimes leave a black bar on the left edge of the picture, or if you didn’t put your whole set up in a full bright photosphere, outside of the background prim it might be black. Let’s fix all those issues quickly so we can have a perfect silhouette. Close up of the issues I need to fix below, note the necklace which was full bright that needs to be cleaned up:

silhouettepicture-fix

If there are no issues, skip this step! Otherwise, grab the brush tool (b) and reset the swatches to black and white. Now using a small round hard brush with black color chosen, color in the parts where the full bright item is messing with our perfect silhouette (the necklace in my example). Now switch to white (x), make the brush a bit bigger (the keys [ or ] make the brush bigger or smaller) and paint white over that right edge that has a black line, or any edges outside of full white background prim that are black. When it’s fixed, continue…

15. Select the black and white layer and hit “select all” (control/command A) then copy (control/command C). Deselect by hitting control/command D. Now turn off the visibility of this layer with the little eyeball in the layers palette.

16. Now select the color layer and hit the button at the bottom of the layers palette to add a layer mask. (button shown below with a red circle)

add-layer-mask1

The mask added will be all white. Now, Alt+click on the white layer mask thumbnail image on the layer and the image is going to turn all white. This means we are viewing JUST the layer mask. One way you can tell you are viewing just the layer mask is that the eyeballs in the layer palette go dim. See image below, the red circled area is where you should Alt+click.

view-mask

Now, hit paste (control/command V).

17. One tiny more step: while still just viewing JUST the layer mask, we need to invert the mask (control/command i). On a mask, the parts that are white will show through, the parts that are black go invisible and the parts that are gray are partly shown through. So we need to invert the colors of this so it works correctly.

18. Now click on the the layer thumbnail for the on the color layer, the lil square image that shows the preview of the layer (circled in red below), and the view will return to normal and you have your cut out picture!finished-layer

The cut out picture in photoshop:

finished-image

Now just drag and drop your cut out image onto your background.

*** There is one caveat: items worn by the avatar that have full bright turned on will cause issues with this method. Depending on the item or it’s size it may make this method not work (for example: full bright hair). If the item is mod, you can turn OFF full bright for the silhouette picture (but turn it on for the “color” picture). If it’s a necklace or something that is inside of the “outlines” of the avatar/shape you want to cut out, it’s pretty easy to fix as I showed in step 14.

This may seem a bit long and involved but the steps are quite easy and once you do it a few times it’s very very fast, much faster than any other method and much more exact.

Enjoy and happy compositing!

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26 Comments leave one →
  1. April 2, 2009 5:51 pm

    What a fantastic tutorial! I was having such issues with alpha hair and shirts!
    ❤ T

  2. April 2, 2009 6:15 pm

    yey I love it when I learn something new! The full contrast silhouette is super clever! Thank you for sharing this and making life a little easier for us! Hugs Chance

  3. April 2, 2009 8:48 pm

    oh i MUST try this…thank you so much for sharing…GREAT tut!

  4. April 3, 2009 9:34 am

    Thank you for this tutorial! ❤

  5. April 3, 2009 9:44 am

    This is such a nice tutorial! I posted a link to it in the big SL group on Flickr. I know everyone will be really excited to try it out. Thanks so much for the lesson!

    http://www.flickr.com/groups/secondlife/discuss/72157616307688600/

  6. QueenKellee Kuu permalink*
    April 3, 2009 12:32 pm

    Thanks for all the nice comments, guys. Glad it’s useful! I hope to share loads of tuts and tips in the future as well. 🙂

  7. April 6, 2009 8:08 am

    That was very clever (nice WindLight technique) and well-illustrated. I gotta blog this shortly @ http://tr.im/sltnt

  8. QueenKellee Kuu permalink*
    April 6, 2009 1:15 pm

    Thanks for blogging this Torley!!!

    I’ve been racking my brain how exactly I stumbled on the technique (honestly, it was a long frustrating process trying to figure out how to make a fast clean alpha channel), and I’m pretty sure it was a memory of one of your presets that inspired me to try to do it with windlight settings. So thank you Torley!!

  9. Lolaa permalink
    April 7, 2009 6:42 am

    My loving SL hubby gave me the link for this tutorial, isn’t he cute?
    … and I must admit it ROCKS!
    I didn’t try it yet but will probably use it and get rid of this “let’s crop the background” thingie for some pics. This is priceless.
    Thank you!!

  10. April 10, 2009 5:50 am

    Nice work, QueenKellee Kuu!

  11. Nieve Thor permalink
    April 12, 2009 9:06 pm

    Thank you so much for the tutorial. It’s really good. * hugs*

  12. August 3, 2009 10:48 pm

    QK, are you ever gonna blog again???? 😦

    ❤ Em

  13. August 31, 2009 11:10 am

    Thank you! Thank you! Thank you!!!

  14. September 3, 2009 4:35 am

    wow, that is awesome, i can start using this right away. thank you for being so thorough =)

  15. MistyBlue Brandi permalink
    October 29, 2009 6:34 am

    Hi, thanks so much for this tip. It’s amazing. Now i do have a small question, when i did change the lighting to black and white i noticed that my whole body became black but my hair stayed red. What did i do wrong?

  16. Jolene McAndrews permalink
    August 29, 2010 10:43 am

    This is…AMAZING! THANK YOU SO MUCH!

  17. December 13, 2010 9:52 am

    Well I don’t do “green screen” shots but that was VERY interesting. Love the old time silhouette look and will definitely play around with that. Great job and TY! Realize this is an old post, but it is still going strong and being linked to 😀 Ain’t that grand.

  18. Breexirrephop permalink
    March 30, 2011 8:38 pm

    Hello,
    Just wanted to introduce myself.. Im Sean… glad to be here! Does anyone have any recommendations / advice on using this site?

  19. August 21, 2011 2:15 am

    Thank you, thank you, thank you! 🙂

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