| iTool User's Guide: Working with Images |

## Manipulating the Image Display

The iImage tool allows you many options to manipulate your existing image displays. Once you have visualized your image, you may rotate, flip, translate, scale, and zoom as well as modify image properties, scroll, and select image ROIs. The following options are available for manipulating images.

For more information on manipulation tasks which are common to iImage as well as other iTools, see Manipulating the Display.

### Rotating an Image

The rotate operation makes it possible to rotate the image within the visualization by a specified number of degrees. To rotate your selected image, select Operations Transform Rotate Data. For more information about rotating, see Rotation.

### Scaling an Image and Byte Scaling an Image

It is possible to scale the pixel values within an image by a specified scale factor. To scale your image, select Operations Transform Scale Data. For more information on scaling data, see Scaling.

Note When working with byte data, the default byte scale range is always 0-255. Therefore, even if data ranges from 0-100, it will display using 0-255. This may cause visualized data to appear darker.

### Inverting an Image

You can also invert the data associated with your image, or with each channel of an RGB or RGBA image. If the data is byte data, the inversion occurs relative to the maximum byte value (255). Otherwise, the inversion occurs relative to the maximum data value per channel. To invert your image, select Operations Transform Invert Image.

### Flipping an Image

You can flip your image within the data space either horizontally or vertically. These operations flip the actual data associated with the image. To flip your data, select Operations Flip Flip Horizontal or Operations Flip Flip Vertical.

### View Zoom

View Zoom allows you to zoom in or out on a specific area of the image display area. To zoom in or out in View Zoom mode click Zoom on the toolbar or select a percentage value from the View Zoom droplist. For more information on working with View Zoom, see Zooming.

### Canvas Zoom

Canvas Zoom allows you to increase or decrease the magnification of the entire display canvas (which may contain multiple views, depending on the layout) by a specified percentage. Canvas Zoom is available by selecting a percentage from the Window Canvas Zoom menu. For more information on working with Canvas Zoom, see Zooming.

### Pixel Scaling

The pixel scale represents the number of window pixels used to display a single image pixel (horizontally and vertically). Pixel scaling is shown on the image panel (which appears on the right side of the iImage tool) and can be manipulated via the View Zoom manipulator on the iImage window toolbar and using its accompanying pull-down menu.

When an image is first loaded into iImage, the X and Y pixel scales are by default set to 100% (one window pixel is used to display one image pixel horizontally). Typically, when iImage first displays an image, the view zoom factor matches the X pixel scale. Changing the view zoom factor also updates the pixel scale labels.

If the currently selected image has been rotated, or if the visualization has switched to 3D (for example, because a surface was inserted), then the pixel scale labels are set to an empty string.

### Region Growing

The iImage region growing operation lets you apply a region growing algorithm to the currently selected ROI. A new ROI is then created and displayed. To apply region growing to your ROI, select Operations Region Grow. You can then select the region grow method (by threshold or by standard deviation).

### Adding Annotations

Annotations can be added to label or describe image visualizations displayed in the iImage tool.

The following types of annotations can be added to iImage displays:

Table 10-1: Types of Image Annotations

Table 10-1: Types of Image Annotations
Image Annotation Type | Description
--- | ---
Text | Single lines or multiple lines of text can be added to a visualization to provide a label or description
Line | Straight line annotations can be added to a visualization to link labels to objects or to identify an object
Rectangle | Rectangular annotations can be added to a visualization to identify rectangular areas
Oval | Oval annotations can be added to a visualization to identify circular areas
Polygon | Polygon annotations can be added to a visualization to identify areas bounded by a multi-sided polygon
Freehand | Freehand annotations can be added to a visualization to identify an area

For more information on creating and using annotations, see Adding Annotations.

### Line Profiles

You can plot image pixel values along a selected line. These values are extracted as a line profile of part of your image visualization and displayed in a new iPlot window:

1. From an iImage window with a visualized image, click on the Line Profile icon on the toolbar.

2. Use the mouse to position the jagged-edge line profile tool over the place which you wish your line profile to begin and click.

3. Drag to the ending point of your line profile and release.

4. A new plot window appears showing a plot of the image pixel values that fall along that line.

Once a line profile has been drawn, it will remain until deleted. The line may be translated (or its endpoints moved individually). If it is translated or edited, the profile plot will automatically update.

If you dismiss your Plot Profile window and wish to have it back again, from your iImage window, with the line selected, choose Operations Plot Profile and the Plot Profile window will reappear.

Note Line profiles on map projections always connect points using the image coordinates (either degrees or meters). See Registering an Image for more information on image coordinates.

### View Panning

To pan an image, select the View Pan tool button on the toolbar and then click on the image and drag until it is in the desired location. Panning causes the extents of the visible portion of the view to be shifted.

### Cropping an Image

The iImage crop manipulator button allows you to crop your image to your specified size and dimension. It also allows you to translate and resize the crop box, and then apply the crop to the currently selected image or images. The button appears in the toolbar as shown in the following figure.

Figure 10-10: The Crop Manipulator Button on the Toolbar

Figure 10-10: The Crop Manipulator Button on the Toolbar

The crop box will appear only if information has been set and is applicable to the currently-selected image. If the crop box information has not been set for the crop operation, or does not fit within your image, then no crop box appears. For more information see Cropping Images

If no crop box visual is present, you can click using the mouse anywhere on an image and drag to create a crop box.

Note All portions of the image that fall outside of the crop box are grayed out.

Once a crop box is present, it may be translated (by clicking and dragging anywhere within the crop box, or along its edges) or scaled (by clicking and dragging on one of the scale handles). A new crop box can also be created by clicking anywhere within the gray area outside of the current crop box.

The arrow keys can also be used to translate the crop box (when the mouse location is anywhere within the crop box or along its edges).

When your crop box is correctly sized and positioned, you can crop the image by:

- Double-clicking anywhere within the defined crop box

- Right clicking to invoke the context menu, and then selecting Crop

- Selecting Operations Crop from the iImage tool.

IDL Online Help (March 01, 2006)