On Tue, Sep 15, 2009 at 4:32 PM, Bob Meetin wrote:

Subject says it all. I have a large assortment of product pictures which I need to give uniform backgrounds, preferably white. Can someone point me to a tutorial that discusses how? You can see a representative sample image at: http://www.dottedi.biz/images/diagnostics/DSC_4355.JPG. They can probably live with the shadows if I can lose the bulk of the background.

The documentation :)

http://docs.gimp.org/en/gimp-tool-foreground-select.html

(not sure which version of Gimp it was written for or which version you're using)

On Tue, Sep 15, 2009 at 6:04 PM, Bob Meetin wrote:

I have seen this before but never used it for a project.  Okay now I played with it for a few minutes.  There must be some trick/finesse to getting it to zero in on the subject, really on the subject's edges.  By following the instructions in Figure 13.26 and keep redrawing the line the border gets pretty mixed up in the shadow areas especially.  Maybe it's my inexperience, but I can actually get a smoother edged selection by using the Paths tool.

Paths tool is a good choice.

Here's a "poor man's isolation method": http://yfrog.com/b5dsc4355retouchj

This is just a levels adjustment (Colors->Levels): "auto", then pull the highlight slider in toward the center. As you can see it's not perfect, but if the BG is the same on all the pics, it might be a time-saver since a little erasing here and there should be enough to clean up afterwards.

HTH,
Chris

On Wed, Sep 16, 2009 at 7:02 AM, Bob Meetin wrote:

Subject says it all.  I have a large assortment of product pictures which I need to give uniform backgrounds, preferably white.  Can someone point me to a tutorial that discusses how?  You can see a representative sample image at: http://www.dottedi.biz/images/diagnostics/DSC_4355.JPG. They can probably live with the shadows if I can lose the bulk of the background.

Thx, Bob

For this kind of thing, there is the name 'greenscreening', in which a matte, contrasting color is used as a background for an object, allowing the object to be easily separated from the background.

In that case, Foreground-select is ideal. However, you basically have the opposite: A photo of a bluish-gray object on a bluish-gray background. Naturally this is very hard to separate automatically!
So for such pathological cases, paths is probably a better choice.

Smoothness is not a big deal (in fact the selection created by foreground-select is entirely binary, no smoothing involved)... this is because you can convert the selection to path and then that path back to selection if you want it smoother.

If I needed to handle your example in the way you want, I would: * use foreground-select to get a rough approximation (make sure that there are no 'holes' by marking areas as foreground as needed) * enter QuickMask mode (click the icon to the left of the scrollbar) * select paintbrush with an appropriate brush and black color, paint away the wrongly selected parts
* exit QuickMask mode (click the icon to the left of the scrollbar) * Select->To Path
* Tweak the path if needed
* right click on the path in the Paths dialog -> 'Path to Selection'

If your example wasn't pathological (ie if it had a good contrasting background), I would just use foreground select, convert to a path, tweak the path, and convert it back to a selection.

Afterwards in either case, I'd probably just Select->Invert and fill with white (like this: http://i26.tinypic.com/bdpjm0.jpg )