How do I separate line sketch from a scanned background? Pics with indept questioning


#1

My question is simply this:

What is the BEST AND QUICKEST step by step, easy-to-understand process for separating/selecting a pencil-sketch from a high-def scanned image drawn on regular sketch paper, using Adobe Photoshop CS3 Extended?

(See attached pics for examples of sketched drawing I made/scanned. Sorry for poor quality.)

My question explained in detail:

I want to know how to take my scanned pencil drawings and separate the sketched line drawing from the grainy debris-cluttered “white” background so I can delete this said background, making it transparent (At that point I would fill in the white background with solid color on a different layer underneath, letting the white “shine” through.).
I want to do this without losing a huge amount of line detail, like what often is done with manual lasso-tool selecting, as well as manual pencil erasing at 100% (or similar percentiles).
I don’t like using “Multiply” and I like having the sketched outlines as it’s own layer.
I don’t really use pens, although I have and the results is better, but the problem remains the same.
My whole goal is to find an effective way of doing this for pencil sketches.

Techniques I currently use:

Step by step this is what I do to remove the white background from the pencil sketch as it is. After I will explain the negative effects because of it, and why I am searching for a better way:

Process 1:

1: I scan the picture in and upload it at high resolution, see “Line-select-01.jpg” attachment for an example and the specs of the pic at this point.
2: I change the “background” layer to “Layer 0” for the sake of editing.
3: I select “Channels” and then I select the dotted circle at the bottom named “Load Channel as selection”.

4: Normally for my lower-qual pics it would select the entire border of the picture AND some of the black outlined sketch (thanks to my previously lower-quality scanner).

However with my new scanner it simply selects the entire border of the picture. When you zoom in you can see that it selected LOTS of small dots of gray within the sketch making up a line. Unfortunately because of the light nature of the sketched pencil lines alot of the detail gets lost and it selects, maybe, 70% of the actual grays in that line.

5: I now hit the “Delete” key removing everything but what is selected.
6: I deselect everything.
7: I create a new layer underneath Layer 0, and I fill that with white completely.
8: As a result, I get the same picture as before, except maybe alittle bit lighter. See “Line-select-02.jpg” for comparison to the first. See “Line-select-03.jpg” for an example of this same picture but at 100% zoom. As you can see the once-even line is now grainy from the deleted pixels.

If there is better settings, or applications then what I have stated for this process, please list and explain them so I can mimic them! I might just have the wrong settings for this type of application to be successfull.

Problem:

I would use this as a preferred method of selecting, however I can’t control which “range” of gray it should or should not delete when I do so! I suspect there is a way of telling Photoshop,

“THIS value of black/gray up to THIS value of white/gray MUST remain in the picture…everything else should not be selected or deleted.”

This would make this whole process so much easier.

Process 2:

Here is another way that I select lines while separating the background.

1: I open the picture, same as “Line-select-01.jpg”.
2: I grab the “Magic Wand” tool and change the tolerance to 25%
3: It selects noticeably more of the outline, but still does not select it all. If I drop the percentage any more, it tends to select alot of the white background also, which is unadmirable.

If there is better settings for the magic wand that I should use, please list them so I can use it.

If I resize the picture to a much smaller size (lets say, 1000px by 700px, or whatever), it does clear up the grainy nature of the picture and outline making the lines smooth again, but the problem of the grain reminance in the background is still there and is noticeable when I add colors other then white as the background.

Not only that, but it is difficult coloring with the level of detail that I want with this method, since the outline is basically the same width of a single pixel at places. Not very good for auto coloring effects like “gradiant” or whatever.

Conclusion:

I just want to know if there is any quick ways of doing this with only Adobe Photoshop CS3 Extended! Do other artists really have to get it “as close as possible” and then spend hours cleaning up the pixels until they get the outline just the way they want? Is there a better, simpler way that I havn’t thought of?

Be aware that I am not really interested in using Illustrator or Corel painter, however if these programs have an interesting way of doing this very same thing, please share…I might convert.

I hope this helps. I am really desperate for some answers, and would appreciate any help, even links to tutorials would be appreciated.

Thank you all for reading this.

vjm3


#2

Sorry, I had attached more pictures, but they have dissapeared.

I will attach them in this post.

Sorry again…

“Line-select-04.jpg” is an example of color behind the gray grainy layer, not fully removed of pixels.


#3

adjust it with levels to get as good sketch as possible (the white areas should be really white), then just pop it on top as a layer instead of background and set the layer mode to multiply

but a sketch like that would only take about 10 minutes or so to hand trance with the pen tool and the results are worth the time i think. thin perfect lines


#4

Well thank you for replying, however I really don’t like using Multiply.

I want the sketched layer to be just solid lines of the original sketch without the white background or dust particles. I will try messing with the levels again.

Ten minutes huh? Clean up work takes me hours usually. I must be doing something wrong.

Is there any other applications that help with this sort of thing? Maybe something that isolates certain varieties of gray, but deletes any value under it?

Anymore suggestions?


#5

Go here (Flamming Pear website) and download the “free plugins”
It has a filter that can be used in photoshop or painter named ghost (once installed in photoshop plug-ins folder you will find it under filter/flamming pear/ghost). It should do what you need. I don’t know if photoshop has this kind of tool anyway but this plugins is really easy to use, just one click on filter name.
This kind of tool can also be found natively in another software like PaintTool SAI under layer menu/Luminance to transparency. I am suspecting this software would make your life easier depending of what kind of end result you want to achieve.

Solid lines? I cannot help you for that, do you want to use it for your end result?


#6

This PS Action removes all white from a page with one click:

http://www.adobe.com/cfusion/exchange/index.cfm?event=extensionDetail&loc=en_us&extid=1044908


#7

JOEPERIS YOU BEAUTIFUL MAN!

This does not get rid of the black “speckles” made in the background from the paper…but atleast now I can color on the layers underneath before I remove this debris!!

My only intimidating with drawing and scanning pics is the huge hassle it takes to remove the white from my backgrounds without ruining the black pencil line quality.

This program does just that subpurbly!! (Took awhile to get use to using “Actions” but now i’m flying high ^^)

You are a scholar and a saint! Now I am no longer imtimidated by drawing on the computer!

Thank you everyone for your help. My question has been answered! God I love this site’s support and community!!

((lol apparantly CGTalk is a nazi about their exclamation makr usage. God forbid I attempt to “express” anything on a site dedicated to the advancement of art through computer graphics @@ ))


#8

If your original image is less then 2500 pixels you can select the whole canvas and click Edit>Define Brush Preset and make it a brush. Create a new layer and click once (a mouse works better then the wacom stylus here) with the brush at 100%. PS has a 2500 pixel brush size limit so that stops you from using this on real big scans unless you wanted to try to piece them together. I’m also not sure how much information might be lost with this method since there isn’t any control when making a brush but it seems to work well for me. You can also mess with the opacity or click more then once for value changes.


#9

you could a also use ‘blend if’ on the layer

http://www.cgtextures.com/content.php?action=tutorial&name=blendif

should give you a pretty good result and you could mix it with the above ways too.


#10

Get the levels as good as you can at the scanning stage. Don’t wait for PShop to get the levels correct.


#11

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