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Thread: Advice for scanning lineart with blue pencil?

  1. #1

    Advice for scanning lineart with blue pencil?

    Hi everyone,

    How do you guys scan your black and white line art to get that black parts purely black without losing detail?

    If I scan line art as a color scan, it takes a while to remove the blue pencil using the Hue/Saturation setting in Photoshop, and I can never get the black portions truly black. Like in this picture http://farm4.static.flickr.com/3128/...04ec6de1_o.png if you look at panel 6, you can see that most of the black space behind the woman and in the outline of the glasses is not truly black (It may be easier or harder to see depending on you monitor's gamma correction). I adjusted the levels in photoshop, and also the brightness/contrast but I still can't get it completely black without using the paintbucket tool on the larger spaces that should appear in black.

    If I scan in black and white (then saving as bitmap), I don't have to worry about the scanner picking up the blue pencil but I lose some of the thinner finer black lines I might make with a Hunt 102 pen.

    If I scan in greyscale it will be impossible to get rid of the blue pencil marks since they will come out grey.

    Any advice?

  2. #2

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    I realize you're probably looking for some Photoshop and/or scanning advice, but I approached this problem from a different angle.

    I found scanning inks with blue pencil underneath was always a drag for exactly the reasons you listed above. My solution was to scan my pencil work, color it blue or red in photoshop, and print out the REVERSE colored image on a piece of bristol.

    Then I just inked over the reverse image face down on a light box. The finished inks were pristine for scanning and if a messed up, I could just print out another pencil scan.

    I'm sure others could probably help out more with removing color and such, but I thought I'd throw that out there.

  3. #3
    First, look for RGB filters. The blue filter will remove the blue, the red will make blue show as black. Not all software has this feature.

    Lacking those, use White Point/Black Point settings. Set White Point to the DARKEST blue pixel, set black to the LIGHTEST washed out grey pixel. Scanned in greyscale, this will remove about 90% of the blue. Use Levels or Curves to finish cleanup.

  4. #4
    Ma-Ma's not the law... I'm the LAW! [SUPPORTER] 50%grey's Avatar
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    Speaking of blue line, I want to do the complete opposite.

    I want to scan my pencils into photoshop and then make them blue lined to print on boards to ink.

    What the specific color that non repro blue is in photoshop,and does anyone have an efficient workflow for this?
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  5. #5
    Cyan. The C channel in CMYK. Try 30% and adjust from there.

    Scan in grayscale.
    Clean with Levels, Curves or Threshold.
    Select all, Cut, convert to CMYK.
    Create Alpha Channel #5, Paste, Select channel.
    In Layers, Fill with 30% Cyan.

    Make sure channels 2-3-4 are empty. Avoid RGB. Primaries in light and primaries in ink are two different things

  6. #6
    Ma-Ma's not the law... I'm the LAW! [SUPPORTER] 50%grey's Avatar
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    Thanks Smitty!

    Wow,thats perfect. Exactly what I needed.
    Last edited by 50%grey; 10-21-2008 at 07:23 PM.
    "You think this letter on my head stands for France???" - Captain America

    50% grey Folder of Drawing Tips and Tricks

    And Join The Cross Contour Facebook Thanks!.

  7. #7
    Thanks Repo and Smitty. I'll give these suggestions a try tonight.

  8. #8
    Member Hofling's Avatar
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    I'm horrible when it comes to Photoshop, so if anyone could fill me in on where to find that alpha channel thing - without mocking me too much - that would be great

    edit; Nevermind. didn't know that any new layer in the channel tab would be an alpha channel. Silly me.

    edit 2, Nevermind that "nevermind" I truly suck at PS. It's just gray on the screen. I'll just go to sleep and think about how much I suck.
    Last edited by Hofling; 10-22-2008 at 02:02 PM.

  9. #9
    As you've discovered, Alpha Channels are those we create. CMYK channels represent color separations or printing plates. Alpha Channels are "drawers" where we store masks or stencils.

    If it's grey, you're either looking at the Alpha Channel or Channel #1 alone. All Channels, when looked at individually, will appear grey. Note Channel #0 is NOT a Channel. It represents all 4 channels combined. Using Alpa Channel #5 as a stencil, fill with Cyan in Layers or Channel #0.

  10. #10
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    Thxs Smitty... I'll try myself your tips.

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