Drawing editing problem

[usamaru]

How do you control the line weight when large black line drawings (8 1/2" x 11")
are scanned using Photoshop CS4 and reduced to thumbnail size (4 cm x 5 cm)
The line weight becomes very thin and faint when the black line drawing is scanned
and the size reduced. I want to make the line quality thicker, and dark and sharp.

 

[Tom Mann]

I don't know of any semi-automatic way to do what you want within PS. One can trace over the overly thin lines in PS with the pen tool and then stroke the path, but that is quite labor intensive. You can try to use mathematical morphological operators such as dilate and erode on the the lines, but (a) I have never had terribly good luck with these, and (b) you will likely have to move to either MathCAD or ImageJ because I don't think these operators are available withing PS.

If I was doing a substantial number of such scans and they were sufficiently important, I would probably take the time to convert each into a vector file in Adobe Illustrator using the Image Trace facility in AI. Then you can scale everything individually to your heart's content.

HTH,

Tom M