Transparency in an image means changing the pixel value so you can see through the image to whatever is in the background. In case you would like to replace a certain color in the image for transparent you can do it with ImageConverter Plus. Just add “Replace color” operation to the current profile and specify the color you want to be replaced with transparency. If you want to replace color gradations, you should use “tolerance” option available in this operation. Please note that not all the image formats have the capability for adding transparency, so your choice will be limited to PNG, GIF, TGA, BMP, TIFF, MNG, and PSD images.