Graphics

Both image displays and line plot displays can be annotated with graphic items. The graphics serve as functional elements when they designate a region such as a crop or they can serve as annotation elements where they annotate the data.

Graphics can be named and the label will appear next to the graphic.

Graphics can be edited in uncalibrated or calibrated coordinates.

Most graphics can be added using either the menus or the tool panel. See Tools.

You can select graphics by clicking on them.

You can deselect all graphics by clicking somewhere outside any graphic.

You can select or deselect multiple graphics by Control key (Windows) clicking or Command key (macOS) clicking on additional graphics.

You can delete graphics by selecting the graphics to delete and pressing the Delete key or choosing Edit ‣ Delete.

You can cut, copy, and paste graphics.

If you have trouble selecting a graphic that is behind another graphic, try clicking on the control points of the graphic. The control points take priority over the middle of graphics further forward.

Image Graphics

Several graphics are specific to image displays.

Point

The point graphic can be placed on an image display.

You can add a point graphic using the Point tool in the tool panel.

You can add a point by using the menu item Graphics ‣ Add Point Graphic.

You can edit the position of the point in the Inspector panel.

You can edit the position of the point by dragging.

Line

The line graphic can be placed on an image display.

You can add a line graphic using the Line tool in the tool panel.

You can add a line by using the menu item Graphics ‣ Add Line Graphic.

You can edit the start, end, length, and angle of the line in the Inspector panel.

You can edit the end points of the line by dragging each end point. Holding the Shift key while dragging will limit the line to be horizontal, vertical, or at a 45° angle.

You can change the position of the line by dragging in the middle along the line.

Line Profile

A special line graphic can be used as the source of the line profile computation, which produces another data item with data of the image underneath the line.

You can add a line graphic using the Line Profile tool in the tool panel.

You can add a line profile by using the menu item Processing -> Line Profile.

You can edit the start, end, length, angle, and width of the line profile in the Inspector panel.

You can edit the end points of the line by dragging each end point. Holding the Shift key while dragging will limit the line to be horizontal, vertical, or at a 45° angle.

You can change the position of the line by dragging in the middle along the line.

Rectangle

The rectangle graphic can be placed on an image display.

You can add a rectangle graphic using the Rectangle tool in the tool panel.

You can add a rectangle by using the menu item Graphics ‣ Add Rectangle Graphic.

You can edit the center position, size, and rotation of the rectangle in the Inspector panel.

You can edit the corners of the rectangle by dragging the corners.

You can change the position of the rectangle by dragging in the middle of the rectangle.

You can rotate the rectangle by selecting it and dragging the rotation control at the top of the rectangle.

Ellipse

The ellipse graphic can be placed on an image display.

You can add an ellipse graphic using the Ellipse tool in the tool panel.

You can add an ellipse by using the menu item Graphics ‣ Add Ellipse Graphic.

You can edit the center position, size, and rotation of the ellipse in the Inspector panel.

You can edit the corners of the ellipse by dragging the corners.

You can change the position of the ellipse by dragging in the middle of the ellipse.

You can rotate the ellipse by selecting it and dragging the rotation control at the top of the ellipse.

Line Plot Graphics

Several graphics are specific to line plot displays.

Interval

The interval graphic can be placed on a line plot display.

You can add an interval graphic by dragging over the line plot with the Pointer tool.

If there are other intervals which prevent dragging, you can select the Interval tool and force an interval to be created.

You can add an interval graphic by using the menu item Graphics ‣ Add Interval Graphic.

You can edit the left and right channels of the interval by positioning the mouse over the left/right channel and dragging. The cursor will change to indicate you are adjusting an edge. It may be helpful to zoom into the line plot area where the interval is located for more precise positioning.

You can edit the position of the interval by dragging within the middle of the interval. The cursor will change to indicate you are dragging rather than editing an edge.

You can hold down the Control key (Windows) or Command key (macOS) to force dragging of the interval instead of editing the left/right channel.

When the interval is selected, it displays the left and right channel values and the interval width.

You can edit the left and right channel of the interval graphic in the Inspector panel.

Channel

The channel graphic can be placed on a line plot display.

You can add a channel graphic by using the menu item Graphics ‣ Add Channel Graphic.

You can drag the channel graphic using the mouse.

You can edit the position of the channel graphic in the Inspector panel.

Masking

Rectangle and ellipse graphics can be used to construct masks. Masks are used in conjunction with some processing operations such as Processing ‣ Arithmetic ‣ Mask and Processing ‣ Arithmetic ‣ Masked.

To create a mask, add one or more rectangle or ellipse graphics. Select the desired masks and use the menu item Graphics ‣ Add to Mask.

You can remove a graphic from a mask by selecting the graphic and choosing Graphics -> Remove from Mask or by just deleting the graphic.

Fourier Filtering

A special type of masking is called Fourier filtering. You can place symmetric masks on complex-valued images and perform Fourier filtering using the menu item Processing ‣ Fourier ‣ Fourier Filter.

The origin of the Fourier filter graphics will typically be in the middle of the center value of the complex-valued image. However, the origin can be changed by editing the spatial calibrations of the image.

Four types of graphics are available for Fourier filter.

Spot

The spot graphic is a rotatable ellipse, symmetric around the origin. It can be used to filter a specific frequency at a specific angle.

You can drag either spot to adjust its position, shape, and rotation.

You can edit the position, size, and rotation in the Inspector panel.

Wedge

The wedge graphic is a pair of lines intersecting at the origin. It can be used to perform filtering along a specific angle and a range of frequencies.

You can drag either line to adjust its angle.

You can edit both angles in the Inspector panel.

Ring

The wedge graphic is a pair of circles centered at the origin. It can be used to perform low pass, high pass, and band pass filters.

You can drag the radius of either circle to adjust its filter frequency.

You can change whether it is a low pass, high pass, or band pass filter in the Inspector panel.

Lattice

The lattice graphic is a repeating filter centered at the origin. It can be used to filter related frequencies occurring at regular spacing.

The lattice graphic consists of two vectors and rotatable ellipses at the end of each vector. The vectors are then repeated across the entire image.

You can edit the position of each vector by dragging the ellipse. You can edit the shape and rotation of the ellipse.