The Display Navigation dialog in GIMP is a convenient way to zoom and pan an image that you're working on. It's worth noting that you can also use keyboard shortcuts to navigate an image.
The Display Navigation dialog splits into two parts, the upper part being the thumbnail of the open image and the lower part is for the selection of Zoom controls.
Image Thumbnail
This is the part of the Display Navigation dialog in GIMP that I especially like. The thumbnail of the active image highlights the section of the image you are currently zoomed in on, with the surrounding image area grayed out. This makes it easy to keep track of which part of the image you are working on and also to move very quickly to another specific location within the same picture.
If you want to move to a different part of the image, you just need to click on the area in the thumbnail and the image will automatically pan to that point. Or, you can click on the highlighted area and drag it around the thumbnail. As you do so, you'll see the image pans to follow the highlighted area.
Zoom Controls
Below the image thumbnail are a number of controls that allow you to zoom in and out of your image. The slider control is pretty self-explanatory and sliding it to the right will zoom in, while dragging it back to the left zooms out. The current zoom level is displayed as a percentage value to the right of the slider.
Below the slider are six buttons that allow you change the zoom level quickly by clicking them. From left to right, these are as follows.
- Zoom Out – clicking this will reduce the zoom magnification in different increments depending on the current zoom level.
- Zoom In – as with zooming out, clicking this will zoom in in differently sized increments depending on the current zoom level.
- Zoom 1:1 – clicking this will zoom you to 100% magnification, so that each pixel of your image is represented by a pixel of your monitor.
- Fit to Window – displays the whole image as large as the window will allow.
- Fill Entire Window – this zooms in so that the entire window is used to display the image, though in most cases the entire image will not be visible.
- Reduce the Image Window – this final control doesn't actually zoom the image, but will reduce the size of GIMP's window to match the current view size of the image. If you are zoomed in so that you are viewing the image at a size larger than the window, clicking this won't have any effect.