Adjustments range from exposure in parts of an image through to using the selecting as part of a composite image. The color highlight in a black and white image featured in this article is one example of further editing to a selected part of the image
The GIMP is the basis for this tutorial because it is free and available for a wide variety of operating systems, not just Windows. The basic principles apply to most serious photo editors, such as Adobe’s Photoshop and Corel’s Paint Shop Pro Photo X2.
The key tool is the edge-seeking tool, Scissors Select, in the Gimp. This is a version of a common image-editing tool appearing in most programs, although the names are often different. The key advantage of this tool is its edge seeking ability. The photographer places a series of dots or points on the image around the edges of the target object and Select Scissors completes the process by joining the dots using a path along the nearest edge defined by a difference in color or brightness.
Its chief attribute is precision and control as the photographer chooses the area with a degree of automatic assistance- speeding up the process – but still leaving the final decisions firmly with the photographer. Where there is a well-defined straight edge, the points can be further apart. For shapes that are more complex and where the edge is of a similar color, or brightness, placing the points closer together helps the software identify the desired edge.
Warning: Always use a copy, not the original image.
Making The Selection
To complete the selection the line of dots returns to the starting point, so click on the starting dot to complete the selection line. The on screen cursor has an indicator that helps identify the start point. To confirm the selection photographers single click inside the selected area. Before the confirmation, but after joining up the dotted line, photographers can drag selected dots to fine tune the selection if the automatic selection is not quite right.
Even after confirming the selection there are other adjusting options, you can add, subtract, or select the intersection of two selections suing the mode icons in the dialog box. This allows a carful and very precise building up of a selection around a complex object.
Save Selection
Photographers can save the image with the current selections in Gimp’s XCF mode for further editing, or to protect a partial selection from any mishaps. This is important as selecting a complex object accurately takes time and patience, as do most complex image editing tasks.
Copy and Paste
Once the selection is complete, the area indicated by the “marching ants” line cut, or copy, the selection and paste it into another image file.
Handy Editing Features
The GIMP offers a number of options to help the selection process.
- The ESC key undoes a partial set of dots before it becomes a selection.
- Pressing the space bar activates a quick pan tool in a zoomed image without leaving the select Scissors mode during a selection.
- There is an area of the pointer (or cursor) for indicating the status of the pointer.
Tips
- Save often.
- Zooming in allows for more dots and for greater precision in adjusting to the edge of the selection area.
Background and shadows can be a problem as around the wheels of the Beetle in the examples. If possible, use a plain colored background that contrasts with subject if it is for part of a composite image.
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