Replace Sky

Discussion in 'The Digital Darkroom' started by haunteddoc, May 20, 2009.

  1. haunteddoc

    haunteddoc Member

    Ok, I am going nuts trying to replace the sky in a pic that has trees. Any good tips on how to make a good clean selection around tree leaves?
     
  2. Tim

    Tim Administrator Staff Member

    which phptoshop do you have?
     
  3. zackiedawg

    zackiedawg Member Staff Member

    Usually, it's best to use a background eraser tool or try a contrast mask selection first, which most versions of Photoshop and Paint Shop have. ; Trees are never easy especially with lots of branches and light peeking through.

    Here's what I do:

    First, copy your desired sky photo as a new layer over your original photo. ; Then move that layer to the background.

    Second, select the foreground layer (the ground & trees), and make a duplicate layer. ; Select the duplicate layer. ; Go to Saturation and reduce it 100% to make it B&W (don't do greyscale conversion as that may change the main layer, which you do not want). ; Then, go to the contrast adjustment tool...you want to boost contrast very high - 70% or so, then adjust the brightness as needed - the goal is to have the photo basically look like a inkblot test - the tree branches all pure black, the sky pure white. ; Adjust brightness and contrast until there are no grey in-betweens. ; This will give you a fairly accurate 'mask' from which to select all of the tree, including the myriad branches and leaves. ; Then using your selection wand, select the black portion of the photo. ; This should select all areas that are black. ; Then invert the selection area, which will highlight all white portions (hopefully, most of the sky). ; Then, click back on the original color ground & tree foreground layer so it is now the selected layer (you can hide the B&W layer to help you see what you're doing). ; Delete the selected area - and you'll see your newly desired sky show through. ; There may still be little bits of sky that didn't delete - usually outlines or halos around the branches. ; I then select the Background Eraser tool. ; Set it to sample only once, rather than continuously, so that when you click and drag to erase a desired portion of the photo, you are only erasing that specific point of color you clicked on. ; You can drag the eraser all over the layer, but it's only going to erase that one sampled color. ; Sometimes a little Soften tool around the edges of the branches can help transition the edges a little better.

    It's no small task replacing a sky around lots of trees!
     
  4. Tim

    Tim Administrator Staff Member

    depending on what version of photoshop you have (i don't know PSP) it can easily be done using the channels pallet. ; let me know if you want an in-depth explanation on this (article?)
     
  5. WDWFigment

    WDWFigment Member

    I use the LAB "Blend If" method. ; There might be something on Google about it.
     
  6. mousefan

    mousefan Member

    I agree with Tim, easy way is through the channels pallet. ; I can give a pretty thorough tutorial if you'd like.
     
  7. haunteddoc

    haunteddoc Member

    I think I know the channels way. ; Go to channels and find the channel that has the most contrast then use the levels adjustment and painting to make a black and white photo. ; Paint the edges with ether white or black with a blend mode of soft light to get the edges. ; Then load the load the channel as a selection? ; Is that the way you are talking about.

    Not sure how to do it via LAB.
     
  8. Tim

    Tim Administrator Staff Member

    if you want to give it a shot, it might make a great idea for a new TMIP article. ; i will give you first dibs on it if you like!
     
  9. Tim

    Tim Administrator Staff Member

    overcomplicated. ; you see what channel has the best contrast and duplicate it. ; then you use levels to get the best possible black and white and ctrl+click the channel name which selects all of the new white areas. ; then replace the sky with a gradient or photo or whatever. ; do it in layers and you can use a mask to fix whatever parts didn't quite look right.
     
  10. WDWFigment

    WDWFigment Member

    Have you tried the method Scott Kelby explains in the 7-Point book (LAB/Blend If)? ; I'm curious as to which you prefer.
     
  11. Tim

    Tim Administrator Staff Member

    i haven't tried that method. ; i like the way i described and once i find a way to do something comfortably, i try to not stray from it. ; i might check out the 'blend if' method just for kicks.
     
  12. haunteddoc

    haunteddoc Member

    I've tried the blend-if method and could never get it to work. ; I'm going to try the other methods posted here and let you know how it comes out. ; I think part of the problem is that there is not a lot of contrast between the leaves and sky as the day was hazy. ; BTW, I am using CS4.
     

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