The Measure Tool is used to gain knowledge about pixel distances in your
working image. By clicking and holding the mouse button, you can determine
the angle and number of pixels between the point of click and where the
mouse pointer is located. The information is displayed on the status bar
or can also be displayed in the Info Window.
When you pass the mouse pointer over the end point it turns to a move
pointer. Then if you click you can resume the measure.
Information is displayed in the
status bar, at the
bottom of the Image window:
-
Distance between the original point and the mouse pointer, in
pixels.
-
Angle, in every quadrant, from 0° to 90°.
-
Pointer coordinates relative to the original point.
6.4.2. Activating the Tool
-
You can get to the Measure Tool from the image-menu through:
→ ,
-
or by clicking the tool icon:
in Toolbox.
6.4.3. Key modifiers (Defaults)
-
Shift
-
Holding down the Shift allows to start a new
measure from the pointed point without deleting the previous
measure. Angle is measured from the previous line and not from
the default horizontal. The mouse pointer goes with a
“+” sign. So, you can
measure any angle on the image.
-
Ctrl
-
Holding down the Ctrl key puts the tool
into constrained straight line mode. The orientation of the
line is constrained to the nearest multiple of 15 degrees.
Ctrl key pressed and click on an end point
creates a horizontal guide. The mouse pointer goes with the
icon.
-
Alt
-
Alt key and click on an end point creates a
vertical guide. The mouse pointer goes with the
icon.
-
Ctrl+Alt
-
This key combination and click on a measure line allows to move
the measure.
Ctrl+Alt
key combination and click on an end point creates a vertical and a
horizontal guides.
-
Use Info Window
-
This option will display an Info Window dialog that details the
measure tool results. The results are more complete on the status
bar.
6.4.5. Measuring surfaces
You can't measure surfaces directly, but you can use the
Histogram that gives you
the number of pixels in a selection.
