It would be great in XnConvert if you could specify the size of a watermark as a percentage of the width or height of the image.
For example, you could have a watermark image which is 1000px square, and you have an image which is 1000px tall and 800px wide. You have it set to add a centered watermark image at 75% of width, so it adds a centered watermark that is 600px square (75% of 800px, which is resized from the original 1000px wide watermark image).
Suggestion: Percentage-sized Watermark file
Moderators: helmut, XnTriq, xnview