Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.sai.msu.su/~megera/gimp/cooltype/hint53/ Дата изменения: Unknown Дата индексирования: Sat Dec 22 07:16:31 2007 Кодировка: Поисковые слова: ngc 6559

Tip supplied by Max Zaroutski.

Want to have really professionally retouched pictures? Read this one carefully.

Almost usually to get precise selection around some object on photo people use magic wand or (in best case) lasso tool.

Using magic wand can only produce good looking effect if you play with tolerance for a long time and the conditions for using it are suitable (for example, you have object on very solid background).



Let's say we have to select an apple from picture above and put it alone onto white background.

Of course magic wand could not be used here. Using lasso tool is very inconvinient - we have wery round edges.. You say you would hold Alt (Option on Mac) key down and use point-and-click method of lasso selection.

Well, this way you would get more or less triangular edges.. And also if you make a mistake you'd have to do everything from the beginning. Here the apple is small but imagine some very complex selection of human body or hair?

The best tool for this is a path tool.



If you click on it and hold for a couple of seconds you get a submenu with 5 different icons.



First one is the actual path tool.
Second is node move tool (used to adjust nodes and move them around).
Third one is used to add new nodes and of course fourth is used to remove unneeded nodes.
The last one is used to adjust curves. (we will use it)

Don't be scared of this - you won't actually need to use curves.

First we will make a draft selection around the apple (just like point and click with lasso tool). Pick up the path tool (the one without + or -). Point cursor to some place on apples' edge and click and release a mouse button. Do not move mouse around while holding the button. This will convert a node to a curved node (we don't need this so far).

Then keep clicking and releasing and get a selection around the apple (you think yourself how far should each point be from another - it depends on roundness of the object).

Now you should have a more or less triangular-edged path around the apple. You can pick node adjust tool and move points around to get it more precise. I suggest set zoom to 250-300% to see the actual edge better.

Now the most complex part of the selecting. Pick up adjust curve tool (the last one in the toolbox). Then VERY carefully click points which edges look too trianglish and without releasing mouse button slowly move mouse according to the direction of edges (you have to make the selection edges lie around the object).



Once you have it all done you will have to turn your path to selection. By the way, having a PATH instead of SELECTION in a file is also good because path takes much less space than additional selection (that is actually a channel).



First bring up Path palette. (Window>Show Paths). Then double click on path and rename if you want to save it. Now click small triangle in the top right corner of palette window and choose Make selection.... Use anti-aliasing and set feather depending on image size. In this example I used 0.5 pixels.

Now you can have it as a layer (hit Ctrl-E on PC or Cmd-E for Mac) or just fill area around it with something (don't forget to invert the selection for that :-)

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© 1997 Nick Ustinov.