What's new

Cartoon - Remove Photo Blue


TonyCooper

Well-Known Member
Messages
85
Likes
41
My son draws cartoons on a sketch pad, scans them, brings them into Photoshop 22.3.1 (64 bit Windows using Adobe's subscription plan). and sometime adds effects or colors.

He currently does a rough sketch in pencil and then inks the sketch. He has to erase the pencil lines, and that takes a lot of time. I suggested he use a non-photo blue pencil and see if he can drop the blue in PS.
I can do this using Curves twice: once to drop the blue and a second time to restore the blackness. Attached is a sample before and after.

Is there a better way to do this?

Someone suggested it can be done better in Illustrator, but my plan does not have that. His does.


2021-04-20-3.jpg
 

Rich54

Guru
Messages
1,105
Likes
2,134
Are you familiar with Blend-If sliders in the Layer Styles window?
I copied your Before image to a new layer and then, below it, I added a layer filled with the same background color as the Before image.
Then, on the top layer, I opened the Blend If sliders, selected the blue channel, and moved the sliders until the blue disappeared (see red arrow).

1618966300329.png
 

TonyCooper

Well-Known Member
Messages
85
Likes
41
Great. That works as well as Curves, and has the advantage of a dedicated set of steps. Using Curves is a guess-and-go.

Thanks.
 

thebestcpu

Guru
Messages
1,888
Likes
1,723
Hi @TonyCooper
Many ways to get the job done. Here is another.
Assuming that you scan at a reasonable resolution to avoid lots of pixels edges, just add a Threshold Adjustment Layer. The default setting is pretty good yet I moved it slightly to the right to thicken up the lines.
Just another option to consider
John Wheeler

2021-04-20-3-adj.jpg
 

thebestcpu

Guru
Messages
1,888
Likes
1,723
Thank you. An even simpler way.
You're welcome yet good to know multiple approaches. The threshold technique works when all of the color lines are lower luminosity than the black lines and that you have pretty good pixel resolution. Otherwise it may not look as good as the above example.
John Wheeler
 

JeffK

Guru
Messages
847
Likes
986
Why not use a free vectorizer tool?


...or use potrace via script in Photoshop.
Awesome tip on vectorizer. Good to have in the toolbox. Not a freebie though cost is nominal.
Will have to dig in on potrace. Thanks for the heads-up on both!
- Jeff
 

JeffK

Guru
Messages
847
Likes
986
*Correction - Just did a test run and Vectorizer is free for non-commercial use:

1619094478585.png
Thanks again!
- Jeff
 

TonyCooper

Well-Known Member
Messages
85
Likes
41
Regarding the Vectorizer app, to work on scanned drawings saved on his computer would require the Desktop version at a cost of $295.00.
 

JeffK

Guru
Messages
847
Likes
986
Regarding the Vectorizer app, to work on scanned drawings saved on his computer would require the Desktop version at a cost of $295.00.
This morning I was able to get a download at no cost. Tried it again now and a download from the web would be 1 credit = .12 US. You would have to initially buy a 100 credit package for about $12.00 US. That will give you 100 downloads for 12 months. I don't see where a desktop app is needed and certainly not at that cost.

 

thebestcpu

Guru
Messages
1,888
Likes
1,723
Regarding the Vectorizer app, to work on scanned drawings saved on his computer would require the Desktop version at a cost of $295.00.
I may have misread your first post yet had the impression that your son does have illustrator in his plan (or did you mean the person that suggested illustrator).
You can compare one time prices and subscriptions if you want/need a vector based program or not.
Adobe Illustrator can do an excellent job of conversion with its Image Trace functionality.

In the example below, I just set the mode to B&W and adjusted the Threshold. I also has advanced controls such as control the number of paths and also how many corners so you can also make subtle adjustments to the overall look. I have included a PNG file of the result from the very small image you provided and also attached a vector SVG file. For a simple sketch image such as the one your provided the trace process is almost totally interactive.

Thought it would be worth just posting what is possible with another tooll
John Wheeler

Take-out-blue-sketch.png
 

Attachments

TonyCooper

Well-Known Member
Messages
85
Likes
41
I appreciated all suggestions - including the one about Vectorizer - and certainly don't want to sound critical of a suggestion.

However, the question presented was how to eliminate the original sketch lines in a drawing scanned into the computer. The drawing would not be uploaded to the web. Therefore, a "download" is not applicable and desktop version of the app would be needed. Conceivably, the drawing could be uploaded, processed in Vectorizer, and then downloaded, but that's the long way around the barn compared to the other very viable solutions presented.

What may be beneficial about the link to Vectorizer is that some here may find it useful for other purposes, and for that a "Thank you".
 

TonyCooper

Well-Known Member
Messages
85
Likes
41
To clarify for thebestcpu's comment....two different households.

I subscribe to Adobe's "Photography" plan and have PS, LR, and Bridge. My interest is photography only. My son subscribes to Adobe's plan that includes Illustrator and Premier Elements (video), but has never used Illustrator. He does a lot of video editing and cartooning. He is accomplished artistically, and I am not (as evidenced by the sample drawing I submitted). I was interested in a way to eliminate the sketch lines in PS because it would be more simple than him starting the leaning curve in Illustrator. In PS, he can open the scanned image, add the Threshold adjustment layer, adjust the slider, flatten and save.

The Threshold technique does the job admirably. No special blue pencil (like the non-photo blue one) is needed. Any blue or red colored pencil strokes can be removed.

Not that it pertains here, but he will eventually apply color and other effects in the computer using Krita's app, but right now he's printing out the b&w image and hand-coloring. The sketch lines can be removed in Krita, but it's a bit more difficult. This is a hobby, not a profession, and he works full-time so he proceeds at his own speed as time is available.
 

TonyCooper

Well-Known Member
Messages
85
Likes
41
To JeffK....Sorry, I misunderstood what you meant. The "download" is downloading the Vectorizer processing result, not downloading some image.

My error.
 

Top