The Measure Tool is used to gain knowledge about pixel distances in your working image. By clicking and dragging 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.
A common use case for « Measure » is to calculate the angle of rotation when horizon is uneven on a photo. Since GIMP-2.10.4, you no longer have to perform the rotation manually to straighten horizon: after measuring the angle, just click the new Straighten button.
This button can be used in straightening horizontal or vertical lines up: the starting point comes with a small bar that shows the direction.
Quand vous passez le pointeur sur le point d'arrivée, il prend la forme du pointeur de déplacement et vous pouvez cliquer pour reprendre la mesure en cours.
Des informations s'affichent dans la Barre d'état, en bas de la Fenêtre d'image :
You can get to the « Measure » from the image-menu through: → ,
ou en cliquant sur l'icône de l'outil dans la Boîte à outils.
While holding down the Shift key, click and drag from an existing endpoint to create a second measurement line from this endpoint. The angle between the two lines will be displayed. Any endpoint can be moved by clicking and dragging. So, you can measure any angle on the image:
Figure 14.175. Shift modifier
Click on start point and drag following a side of the angle.
Then, Shift-click on start point and drag following the other side of the angle: you get the value of this particular angle.
La touche Ctrl pressée pendant le déplacement du pointeur contraint la mesure à des angles de 15°. Vous pouvez l'utiliser pour faire des mesures strictement horizontales ou verticales.
Ctrl key pressed and click on an end point
creates a horizontal guide. The mouse pointer goes with
the
icon.
In Horizontal or Vertical Orientation modes, Ctrl also toggles between Horizontal and Vertical.
Alt key and click on an end point creates a vertical guide.
La combinaison de touche Ctr+Alt plus un clic sur un point terminal permet de mettre en place un guide vertical et un guide horizontal.
La combinaison de touche Ctr+Alt plus un cliquer-glisser sur une ligne de mesure permet de déplacer la mesure.
In the Auto mode (default), will snap to the smallest angle between the measure line and the vertical or horizontal direction. Horizontal and Vertical allow to override this behavior by specifying explicitly what it should be.
This option will display an Info Window dialog that details the measure tool results. The results are more complete than on the status bar.
Transform, Interpolation, and Clipping are treated in Section 3.1, « Fonctions communes ». Here is an example for straightening a path:
Original image
Draw path
Make path visible
Draw measure line on the segment you want to straighten
Straighten
Figure 14.177. « Straighten » clipping options
Draw measure line
Straighten with « Adjust » option
Straighten with « Clip » option
Straighten with « Crop to result » option
Straighten with « Crop with aspect » option
: click on this button to perform straightening.
Vous ne pouvez pas mesurer directement une surface, mais vous pouvez utiliser l'Histogramme qui vous donne le nombre de pixels dans une sélection.