My question is about finding a object in a specific part of a image. For example, I use this image:

As you can see, you will se two persons walking on the field. I only want to find the second person on the right site of center line

If I use the following script, Mathematica find both.

Show[Image[picture1, ImageSize -> 600],
Graphics[{Red,
Table[Inset[ToString[i],
PixelValuePositions[foto17, {0.07, 0.09, 0.1}, .05][[i]]], {i, 1,
Length [
PixelValuePositions[foto17, {0.07, 0.09, 0.1}, .05]]}]}]];


Is there a way to select a specific part of a image? Fore example, something like this:

-
Masking option. See documentation. –  rasher Feb 12 at 8:45

Here's a quick-n-dirty example, hand-tweaked values. You'll probably want to use more sophisticated means if you have more than a few images to process. You can also use the drawing tools to take your image and manually draw a mask. Many ways to skin this cat...

mask = 1 -
BoxMatrix[
Sequence @@ Reverse@({2, .8} Round[ImageDimensions[foto17]*.5])];

Show[Image[picture1, ImageSize -> 600],
Graphics[{Red,
Table[Inset[ToString[i],
PixelValuePositions[masked, {0.07, 0.09, 0.1}, .05][[i]]], {i, 1,

I simply pasted a copy of the image, invoked the Drawing Tools via Ctrl-D or the Graphics menu, and drew the polygon. Replace the masked=... with masked= <the masked image>, and you're golden - you don't need the first line of my example that generated the simple rectangle mask.