Removeing blue lines in scanned pencil drawings????

DH
Posted By
Doane_Hoag
Jun 2, 2007
Views
1641
Replies
14
Status
Closed
I have tried selective color and color replace, but have had poor results removing the "non reproducing" blue pencil lines from my pencil drawings that I scan into the computer in color.
I use blue lines to lightly block in the drawing before I draw with regular pencils, or during the drawing progress. The pencil lines have dark to very light lines and I don’t want to loose the light lines in the process of removing the blue ones. Does anyone have some trick to share?
Thanks,
Doane

How to Improve Photoshop Performance

Learn how to optimize Photoshop for maximum speed, troubleshoot common issues, and keep your projects organized so that you can work faster than ever before!

MD
Michael_D_Sullivan
Jun 2, 2007
Maybe select the blue channel, then use a threshold adjustment?
DM
dave_milbut
Jun 2, 2007
are you using black or colored pencils for the rest of your drawing? if regular black, scan in grayscale. that’s the purpose of the blue pencil for markups. doesn’t show up during b&w scanning.

if colored pencils, then mike’s got a good suggestion.
LH
Lawrence_Hudetz
Jun 3, 2007
Actually, not quite true, dave. If the blue line has a density greater than the paper density, it still will show up, unless the scan is done only on the blue channel, or in the old analog days, shot through a blue filter or with color blind emulsions.

The same is true with a yellow stain. With the filters available now in PS, match the stain color to a filter color and poof! There goes stain (in b&w only, of course)!

Mike’s suggestion is right on.
MD
Michael_D_Sullivan
Jun 3, 2007
The reason blue pencils are labeled as non-reproducing is that older copying machines and monochrome scanners typically used the blue spectrum for copying, so that blue showed up as white. Now, few copiers or scanners operate in this mode; they create an image using a sensor that is sensitive to multiple colors, whether the ultimate image is to be monochrome, grayscale, or color. This allows pictures and graphics to be reproduced in a somewhat recognizable fashion, and prevents yellow highlighting from coming out black, which is the case when a blue-oriented sensor or light source is used.

By using the blue channel, anything that was blue in the original image will be white or close to it. Black pencil lines, however, will remain black. Using the threshold allows you turn pixels that are above a certain point white. Alterrnatively, use the Levels adjustment on the blue channel to maintain better light/dark black pencil lines.
DM
dave_milbut
Jun 3, 2007
older copying machines and monochrome scanners typically used the blue spectrum for copying, so that blue showed up as white.

yup. that’s what i was basing it on. sorry to be out of date.

ex-big-iron xerox copy jockey,
dave 🙂
P
Phosphor
Jun 3, 2007
DocuTechers of the World, UNITE!

🙂
DM
dave_milbut
Jun 3, 2007
9700 & 9900 here! 🙂 scribble whatever you want in blue pencil, it wasn’t gonna come out.
DH
Doane_Hoag
Jun 3, 2007
Thanks everyone.. sorry, let me try to be a bit more clear. I draw using 2b to 2h regular graphite pencils (not colored) on 100H architectural or onion skin tracing paper. I use blue "non reproducing" pencils for rough perspective layout lines, etc., in the preliminary sketching stages and as I am working in different areas as needed.
When I was working at a company a few years ago I used to take my pencil drawings over to a print shop and on their copy machines the blue lines would not show up in the copies, but at home now, I scan with an Epson Perfection (usually in two scans from 11×17), and quickly piece them togeather in the computer. During the scan I have no filter controls that I am aware of. I then do manipulations of the drawings in the computer, clean them up, etc. I also add more scanned in drawings, etc. to these as layers as needed. I finally print the manipulated drawings out on a HP Deskjet 1220c at 11×17 on HP brochure flyer paper.
LH
Lawrence_Hudetz
Jun 3, 2007
Save them as RGB, Doane, then open the blue channel as a gray scale and correct the contrast. The blue should be gone. If not, send us a sample via Pixentral (http://www.pixentral.com/) and we can take a look.
DH
Doane_Hoag
Jun 3, 2007
Thanks, Lawrence, I do save them as RGB, but I’m not sure of your instructions. I’m not knowledgeable in all areas of PS..

If I go in channels and turn off everything except the blue channel, the blue lines pretty much dissapear in the image window, and if I then adjust the levels for the best retention of the light pencil lines while eliminating most of the blue lines, and then convert it to gray scale, that actually works better then anything I have tried before using the color selection tools. Is that what you were suggesting?
Thanks for your patience, if you want I can post one of the drawings on the link you gave as well. Doane
LH
Lawrence_Hudetz
Jun 3, 2007
Exactly, Doane.

Good Luck!
DH
Doane_Hoag
Jun 3, 2007
OK, I had looked in my CS help file and couldn’t find anything about this.. I guess the days of hand drawn art work are disappearing.. ;~) anyway, thanks for all your help!
JR
John_R_Nielsen
Jun 3, 2007
Right-click on the layer with your scanned drawing, and go to ‘Blending Options’. Choose ‘Blue’ in the ‘Blend if:’ drop-down, and drag the white pointer at the right of "This Layer" to the left.

If you Alt-drag the pointer, it will split in two, with a smooth transition between the two.
DH
Doane_Hoag
Jun 3, 2007
Thanks, John, another good method to add to my notes.

Must-have mockup pack for every graphic designer 🔥🔥🔥

Easy-to-use drag-n-drop Photoshop scene creator with more than 2800 items.

Related Discussion Topics

Nice and short text about related topics in discussion sections