Laser prints and photocopies made at a copy store are the best for making image transfers. These are made with toner instead of ink, and use a heat process to set the toner in place. Toner sits on the surface of the paper allowing it to be released when making a transfer. The reason inkjet copies don’t work is because ink from an inkjet printer absorbs into the fibers of the paper and cannot be released and transferred.
If you’re not sure whether you have a laser or inkjet printer, check to see if the paper is warm when it comes out of the printer. If it's warm, you have a laser printer, if it's not, you have an inkjet printer. All laser and photo copy machines use toner and are the best for image transfers. These can be used to create color or black and white image transfers.