https://phlearn.com/tutorial/color-tone-using-gradient-maps/Imagine a gradient. What comes to mind? We're willing to bet that you're picturing one...
PHLEARN - Light Effects & Color Toning with Gradients in Photoshop.part1.rar
PHLEARN - Light Effects & Color Toning with Gradients in Photoshop.part2.rar
PHLEARN - Light Effects & Color Toning with Gradients in Photoshop.part3.rar