General

@workofart

hmm with pencil sketches theres an option underneath "layer(L)" that says 'luminance to transparency' which basically turns whatever was originally white into transparent, meaning you can color beneath it!

i tend to take photos of my sketches and when i do this i have to turn the brightness and contrast up to make the paper texture disappear (so i would only be left with my lineart) mm.. this usually makes my lineart really pale though, so i suggest copy and pasting the same layer on top of it since it makes it darker.

[b]To draw on top of blueprint layer[/b]
Simple as just scanning the image, setting it as the background, and making a new layer on top of it. Set the opacity of the blueprint layer to lower, and draw on top of it in a new layer.

[b]To turn your lineart into its own transparency layer[/b]
You will need photoshop for this one. You'll have to search it up online since it's a bit of a process.

[b]To cut something out from one thing to another[/b]
You will have to manually select exactly what you want. If you have a tablet you can just select the general area and erase the areas that you don't need. But that's very difficult without a tablet. You will have to select manually without a tablet. It's pretty difficult to get the exact area you need though.

I see, thanks alot for the help!

@UltraLudde:

You can delete layers, add new ones, ect. Just do things on separate layers if you want to avoid a headache.
Just delete the layer you don't want and add in a new one. You can drag layers on the side up and down to order them differently in the "stack".
You can also modify layers by simply drawing on them while selected.

Here's a rushed tutorial on how to do basic lining. There are more indepth tutorials out there, but this might help you.

http://i57.tinypic.com/e656yv.png

EDIT:

I don't necessarily draw how you're describing it, but if you want a different "blueprint," just add in the file you want to use as a new blueprint as a new layer usign the copy-paste thing from before, and move it to the appropriate position in the "stack". You can delete your old blueprint layer using the trash can, or you can hide it by clicking on the eye icon on the layer in the layer pane.

Ctrl + T allows you to transform the selected layer (or part of the layer using the lasso tool), so you can move resize, reposition, rotate the layer as needed.
Just remember: keep everything on a separate layer.

Thanks for the help guys, thought you don't really seem to understand my question.

@LittleTLK Let's take your picture, I wonder if you can [b]change[/b] the layer that you call [b]Scanned Layer[/b] once you chose one. So let's say that you draw your warrior, but then you want a cat beside him. Can you then delete the scanned warrior layer and insert a cat instead?

[quote=UltraLudde]With blueprint I mean, you draw something on paper, scan it to make it digital, and then draw your line art on, I'm really bad at explaining, but thanks for clearing things up with the copy paste thingy![/quote]

Just throw your scanned picture into SAI, reduce its opacity, and create a new layer on top of it:

http://i60.tinypic.com/20nnrs.png

example

[quote=LittleTLK]What do you mean by "blueprint" layer?

And yes, you can cut something out of a work and paste it in another.
Select what you want with the lasso tool, ctrl + x, then go to the other file and ctrl+v.[/quote]

With blueprint I mean, you draw something on paper, scan it to make it digital, and then draw your line art on, I'm really bad at explaining, but thanks for clearing things up with the copy paste thingy!

What do you mean by "blueprint" layer?

And yes, you can cut something out of a work and paste it in another.
Select what you want with the lasso tool, ctrl + x, then go to the other file and ctrl+v.