I use a brush stamp in Photoshop for this and it works very well. Here is the technique I used to create the brush stamp: http://phlearn.com/best-way-watermark-images-photoshop
I use a brush stamp in Photoshop for this and it works very well. Here is the technique I used to create the brush stamp: http://phlearn.com/best-way-watermark-images-photoshop