✔ 最佳答案
In Photoshop, create a canvas that is the size that you want your finished image.
In Illustrator, select the entire image and copy it.
Back to Photoshop - paste it. Your best bet is to select As Smart Object because you can scale it up or down and not lose quality.
Scale it the size you want it (hold the shift key down to constrain proportions.
Hit enter.
Make new layers UNDERNEATH the line art layer and paint on them. If you go out of the lines - you erase it! You can do as many different layers as you want and use layer styles and blending options.