Brighten Image With Gimp. Launch gimp and open the photo that you want to lighten. In this tutorial we brighten the subject in the picture.
Apply a layer mask to the contrast mask and use it to select only parts of the contrast mask. Go over to your layers panel and click on the floating layer. Moving the mouse vertically changes the brightness.
Step 2 click anywhere on the photo and while holding down the left mouse button move the mouse vertically to adjust the brightness.
If you only want the contrast mask to apply to certain areas of the image see my example of this below. If you only want the contrast mask to apply to certain areas of the image see my example of this below. Click the create a new layer icon to convert the floating layer into a new layer called pasted layer by default. If you are adjusting the brightness of an image that hasn t been split into layers the single layer background will be selected by default step 2 open the brightness contrast dialog box.