1- Open image you want to extract.
2. Now go to :Channels Pallet" and watch closely which "color channel" has more/better contrast. In this case it is "blue channel"... so simply drag it to "create new channel" icon to make a copy of blue channel. it will be called "blue copy"
NOTE: if your channel pallet is not visible, then simply goto "Window" in top menu and select "Channels" from drop menu.
3. When "blue copy" is selected, goto "Image" from top menu then Adjustments>Levels.. or simply press Ctrl+L to open level options. Drag the left pointer (black) to right
4. Now goto Edit>Fade Levels or Shift+Ctrl+F and change mode to "Linear Burn"
5. Now select Black as you foreground color.... choose a harder brush of about medium size and change the brush mode to "Overlay" (Alt+Shift+O)... and paint over image untill it gets totally black.
6. Now Ctrl+Click on the icon of that "blue copy" to make its selection... go back to layers pallet and click on the "Add Layer Mask" icon on the pellet bottom.
Note: If this step hides your foreground instead of background...simply press Ctrl+I on layer mask and the selection will be reversed.
Thats it... you have extracted the image
You can now place it on any background. I've placed it on a texture i made in 3 simple steps in photoshop. (i'll add that tutorial here as well if you like it)
I hope I've explained everything.
I will add other tips like how to extract an image with complex background laterEdit: Oh.. there are also some advanced techniques to adjust the channel mask with dog or burn tool... and then refine mask edge....which i'll explain in other thread.






