Within the IPS4 gallery you can change various settings which affect the way in which your gallery works. You will find these settings within the admin cp area shown below. From here you can change the various sizes of images, change logging and RSS settings, and protect your images against copying by implementing a watermark of your own choice within your images.
There may be occasions where you wish for all your gallery images to be watermarked. You can achieve this by switching on the 'Watermark images' setting.
From here you can upload an image which will be used as the watermark image, which must have a transparent background. You can choose if you wish to show these on both the large and thumbnailed images. Note that when selecting this, your gallery content will be rebuilt.