Level

The Level transformation rotates an image so as to make a line you specify either horizontal or vertical. To level a horizon, you mark where the horizon is on the image and the image is rotated to make the horizon level. Or, if the image has verticals that are skewed, you can mark a line in the image that should be vertical and the image is rotated to make that feature vertical. Since a rotated image no longer fits into a normal rectangular grid, the Level transformation provides options for cropping the result image is various ways.

Line Overlay

When the input image is displayed, an overlay line is drawn over the image indicating what part of the image will be make horizontal (or vertical). You can drag either end of the line to position it – if you look carefully you can see it on the left side of the horizon on the left image above. You can drag both ends at once by dragging the line anywhere between the two endpoints. For more precision, you can zoom in on the input image. Switching to the output image displays the result image on the right. The length and position of the line does not matter, just its angle, but longer lines do let you adjust the angle more precisely.

Size Tool bar

This tool bar lets you control how the output image is cropped.

The first button crops the result image so there is no black border visible around the edge as has been done in the example above. Note that this makes the result image smaller than the input image by an amount that depends on the rotation angle. This is the most common option.

The second button makes the output image the same size as the input image. This will show some black border around the edge depending on the rotation angle, but some of the original image will also be lost.

The third button makes the output image large enough to capture all of the input image but it also shows more black border around the edge than either of the other two options.

Orientation Tool bar

This tool bar lets you tell Picture Window if you want to level the image horizontally as in leveling a horizon or vertically as in making a tree or building vertical.

Angle

The control is a readout that indicates the rotation angle (in degrees) specified by the line overlay you have placed.