Why do you have to use only a blue pencil for sketches to scan for photoshop?

why not red or green?





can you use a colored pencil?


lolWhy do you have to use only a blue pencil for sketches to scan for photoshop?
I've never heard that you can only scan things in blue pencil for photoshop. But I can tell you that a blue pencil is used when printing on a press because it will not show up when the negative is shot.Why do you have to use only a blue pencil for sketches to scan for photoshop?
There is a special ';non-photo'; blue pencil, used to make notes and sketches for later inking. This special color will not scan or photograph very well, so, is ideal for this purpose.





It is, simply, a color that the scanner cannot pick up.
the only blue pencil I know of that's used for scanning things is a non photo blue for sketches and planning, then you use black or darker colors to do the clean lines because the non photo blue wont show up in the scan.


you can use any other color on an image, think about it, you can scan color-photos right?


the only thing that might cause trouble in a scan could be graphite because it tends to be reflective sometimes and if it reflects the light you may not get a great scan.