GIMP is a free and open source image manipulation software. I only use a small subset of functions of the software. Here are some tips I keep a record for myself.
Ctrl + Alt + Move Selection
is the shortcut to move selected area of an image.
GIMP adds a “Floating selection” temporary layer in the layer dialog. After you
make the change, click the mouse in another area to confirm the move. The
temporary layer merges onto the main layer.
Sometimes GIMP leaves a hole on an image when you delete the pixels in an area.
Choose menu item Layer
> Transparency
> Remove Alpha Channel
and the area
will show white background.
Some scanned image file has a grey hue on the background. The Colors
>
Curves
tool can be used to remove the background.
If you want to resize a scanned plan image file to a certain size such as Arch D (36” x 24”), you can follow those steps (revised on 10/30/2020).
Image
> Crop to Selection
to
crop to the selected area. Image
> Scale Image
, and lock the Width
and
Height
ratio on the dialog box, and enter the width or height to
desired width (e.g., 36”) or desired height. If you enter the width
36” in this step, the height should be less than 24”. Image
> Canvas Size
, and unlock the ratio. Resize
the canvas size to the final size such as 36” x 24”. Also click the
Center
button on the dialog box. Layer Fill Type
value White
. Put this new layer below the existing
layer and merge the existing layer down. This article will be continuously updated (last update: 10/30/2020).