3. Opening Files

3. Opening Files
	Chapter 5. Getting Images Into GIMP

Revision History
Revision $Revision: 1792 $	2007-03-14	lexa

There are several ways of opening an existing image in GIMP:

3.1. Open File

The most obvious is to open it using a menu, by choosing File → Open from either the Toolbox menu or an image menu. This brings up a File Chooser dialog, allowing you to navigate to the file and click on its name. This method works well if you know the name of the file you want to open, and where it is located. It is not so convenient if you want to find the file on the basis of a thumbnail.

	Note
When you open a file, using the File menu or any other method, GIMP needs to determine what type of file it is. Unless there is no alternative, GIMP does not simply rely on the extension (such as ".jpg") to determine the file type, because extensions are not reliable: they vary from system to system; any file can be renamed to have any extension; and there are many reasons why a file name might lack an extension. Instead, GIMP first tries to recognize a file by examining its contents: most of the commonly used graphics file formats have "magic headers" that permit them to be recognized. Only if the magic yields no result does GIMP resort to using the extension.

Note

When you open a file, using the File menu or any other method, GIMP needs to determine what type of file it is. Unless there is no alternative, GIMP does not simply rely on the extension (such as ".jpg") to determine the file type, because extensions are not reliable: they vary from system to system; any file can be renamed to have any extension; and there are many reasons why a file name might lack an extension. Instead, GIMP first tries to recognize a file by examining its contents: most of the commonly used graphics file formats have "magic headers" that permit them to be recognized. Only if the magic yields no result does GIMP resort to using the extension.

Figure 5.4. The “File Open” dialog.

GIMP 2.2 introduced a new File Chooser that provides several features to help you navigate quickly to the file you are looking for. Perhaps the most important is the ability to create “bookmarks” for folders that you use often. Your list of bookmarks appears on the left side of the dialog. The ones at the top ( “Home”, “Desktop”, etc) come automatically; the others you create using the “Add” button at the bottom of the list. Double-clicking on a bookmark takes you straight to that directory.

At the center of the dialog appears a listing of the contents of the selected directory. Subdirectories are shown at the top of the list, files below them. By default all files in the directory are listed, but you can restrict the listing to image files of a specific type using the File Type selection menu that appears beneath the directory listing.

When you click on a file entry in the listing, if it is an image file, a preview will appear on the right side of the dialog, along with some basic information about the properties of the image. Note that previews are cached when they are generated, and there are some things you can do that may cause a preview to be incorrect. If you suspect that this may be happening, you can force a new preview to be generated by holding down the Ctrl key and clicking in the Preview area.

One thing that strikes many people when they first see the File Open dialog is that there is no way to enter the name of the file using the keyboard. Actually this can be done, but the feature is a bit hidden: if you type Ctrl-L with the dialog focused, an "Open Location" dialog pops up, with a space to type the file name. This dialog is described in more detail below.

	Note
In the great majority of cases, if you select a file name from the list, and click the “Open” button in the lower right corner or the dialog, GIMP will automatically determine the file type for you. On rare occasions, mainly if the file type is unusual and the name lacks a meaningful extension, this may fail. If this happens, you can tell GIMP specifically what type of file it is by expanding the “Select File Typ” option at the bottom of the dialog, and choosing an entry from the list that appears. More commonly, though, if GIMP fails to open an image file, it is either corrupt or not in a supported format.

Note

In the great majority of cases, if you select a file name from the list, and click the “Open” button in the lower right corner or the dialog, GIMP will automatically determine the file type for you. On rare occasions, mainly if the file type is unusual and the name lacks a meaningful extension, this may fail. If this happens, you can tell GIMP specifically what type of file it is by expanding the “Select File Typ” option at the bottom of the dialog, and choosing an entry from the list that appears. More commonly, though, if GIMP fails to open an image file, it is either corrupt or not in a supported format.