How to trace pencil drawings

[Joe Kirkbride]

I am making pencil drawings from the microscope. I need to turn them into black-and-white line drawings for publication.

What I have been doing is:
1. Scan the pencil drawings.
2. Resize the scanned pencil drawing to make it fit the final illustration.
3. Create a new transparent layer.
4. Put the transparent layer above the layer with the scan of the pencil drawing.
5. Make only the transparent layer and the layer with the scanned pencil drawing visible.
6. Increase the viewing size of the image to 1000%.
7. Spend hours very carefully drawing new black lines on the transparent layer matching the scanned pencil drawing below it.

The results are beautiful, but the process is very slow and laborious. Is there an easier, quicker way the trace pencil drawings in Photoshop?

Joe Kirkbride

[YrbkMgr]

Joe,

Here's what *I'd* do - I'd blend out the white, creating only a transparency and the black. Then convert the line drawings to a path (so you don't have to trace). Here's how.

Scan in your image just like you've been. Use Levels to bring up the black and drop any grays that should be white. Alt-Double Click on the background layer to rename it to layer 0. Now Duplicate the layer so you have two copies.

Be on Layer 1, the topmost layer and double click on it's icon in the layer pallet to bring up the blending dialog.

In the middle of the Blending Options dialog is a dropdown called Knockout. Set it to Shallow.

Beneath that are some sliders, one labeled "This Layer". On the right of that slider you see a pointer with a hairline crack in it. Hold down the Alt key while sliding that to the left (effectively splitting the slider apart), and look at your image. The white is gone.

The amount you slide that determines the shades that will be blended into transparency.

Once you are satisfied, create a New Blank Layer. Stamp what is visible by holding down the Alt key (keep it held down) and click on Layer|Merge Visible.

You now have a black drawing on transparent background. Disable the other layers, and Ctrl-Click on the new stamped layer. This will select the non-transparent pixels. Zoom up a bit, click on your marquee tool, then right click on the selection and choose Make Work Path from the pop up menu. The default value in the dialog is 0.5, I usually get better results setting it to 1 pixels - your call.

Once that's done, look at the Paths Pallet, you have a Work Path. Double click that to save it as a Path (Path 1 by default).

Now you can use the pen tool to tweak the path to your liking, load it as a selection and fill or stroke it.

It sounds more complicated than it is.

The other way is to simply use the background eraser and get rid of the white (alt double click on the layer first) and then Ctrl-click the Layer 0 then stroke or fill, no pen tool needed.

Peace,
Tony

[Eric Purkalitis]

Ick! I hate using paths unless I have to. Try duplicating your layer (so you have the original to go back to). Now go to filters/stylize and use the find edges filter. You can then strip out a lot of the background junk by adding a threshold adjustment layer. I think that will draw alot of the lines for you.

If you have to paint some more you might try setting the layers blending mode to something like multiply so you can see the original beneath as you paint. When your done switch it back to normal.

[YrbkMgr]

Ick! I hate using paths unless I have to.




Well, there are at least three ways to do anything in photoshop. If you want precise selections, paths would be one way. <grin>.

[Carl B. Johnson]

Joe,
Download the free trial fo Adobe Streamline, it is quite competent and
may do in minutes what you are trying to do the tedious way.