Take part of image under locator

Question

How to create Manipulator with Locator to take part of an image?

Answer 1

One way that Manipulate[] can control the portion of the selected image with a locator is:

img = ExampleData[{"TestImage", "Mandrill"}];
{dR, dC} = ImageDimensions[img];
Manipulate[
  Show[img, 
    ImageTake[img, {dR-50-p[[2]], dR+50-p[[2]]}, {p[[1]]-50,p[[1]] + 50}]], 
{{p, {dR/2, dC/2}}, Locator}]

This lets you scan around, zooming into the image. Control the size by the integers inside ImageTake[] (set to 50 here).

Answer 2

Of course, this is completely automatic in version 9. If we Import your image and just click on it, we get easy access to a crop tool, as well as others. It looks something like so:

Here's the cropped image: