Question about painting over a scan

[Delfin93]

Hello there!


I am painting with pencile on paper and want to scan these pictures and then paint over it in black, so that you can't see in the end the pencile bt rather just the black paint from GIMP.

Here you can see my picture I painted with pencile on a piece of paper:


And here I tried to paint over it with GIMP but you can still see the lines I painted with my pencile:


Is there a way to let the pencile paint disappear?


Hope for you help and thanks a lot in advance! 

[Ofnuts]

Add a transparent layer above the scan layer and paint on that layer. For checks, add a white layer between these two layers and toggle its visibility ("off" to paint, "on" to check and to produce final image).

[Espermaschine]

im doing something similar at the moment, but my angle is more about inking the sketch in Inkscape
there is a channel on youtube, by Jason Secrest, who has done a ton of inking and colourising videos

i used one of his templates in this thread

he is using a similar technique as ofnuts proposed: reducing the opacity to half and drawing on a new transparent layer
possibly locking the alpha channel on the sketch if you have one

so far im trying to improve a scanned paper and pencil sketch, but struggle with my tablet
i find the tablet too slippery
what can help is using the 'Smooth Stroke' option of the Brush Tool, to get better lines

you can also use a different, better contrasting colour (like red) for tracing the sketch and later change it, by locking the alpha channel and filling it with black

[rich2005]

@Delfin93

You could try the gmic plugin http://www.gmic.eu One of the filters is repair-scanned-documents

[Delfin93]

Thanks a lot guys! I will try it out this weekend and then tell you what worked out the best for me!

And I also have another question:

I want to print this drawing onto a tshirt and it would be very helpful if I could find out how big the drawing will be (in centimenter) before I print it.
Is there an option in GIMP to show me the actual size if I print it out on DIN4 paper?

Thanks a lot in advance!

[Clydaler]

(02-02-2018, 07:34 PM)Delfin93 Wrote: Thanks a lot guys! I will try it out this weekend and then tell you what worked out the best for me!

And I also have another question:

I want to print this drawing onto a tshirt and it would be very helpful if I could find out how big the drawing will be (in centimenter) before I print it.
Is there an option in GIMP to show me the actual size if I print it out on DIN4 paper?

Thanks a lot in advance!

Before you get too far into the drawing, you may find it advantageous to make your gimp image the exact size you want/need for the shirt, and set those parameters in the "Create a New Image" window.  You can set the units specifically to centimeters (cm), then if your original drawing is too small / big for the image, you can resize the image to fit the canvas, use the earlier advice to trace over it, and voila; you have the exact sizes you needed for your shirt.

Let me know when I can order one!

   

[Blighty]

Gimp works in pixels. The image size in pixels is shown in the title bar - top left hand corner.
(Remember to crop unwanted white space off your image)

For the given image size in pixels go to
Image > Print Size
This will show the print size for the current image size in pixels.
Changing the resolution will show the resultant print size.

[Delfin93]

(01-30-2018, 10:06 PM)Ofnuts Wrote: Add a transparent layer above the scan layer and paint on that layer. For checks, add a white layer between these two layers and toggle its visibility ("off" to paint, "on" to check and to produce final image).

Thanks a lot, this worked out for me!
Here the result:

(01-31-2018, 09:03 AM)rich2005 Wrote: @Delfin93

You could try the gmic plugin http://www.gmic.eu One of the filters is repair-scanned-documents

Had some trouble installing the Plugin, then it worked out with the help of some turtorials. Awesome filters but sadly the result was not clear enough when I used the "repaired documents filter". One could still see the pencil. But I'm sure it's a usefull tool for other kind of works!

[rich2005]

Sometimes you have to make suitable adjustments and/or apply a second filter to get a result that pleases.  
You might get a better result, still using G'mic 
1. Repair -> Remove hot pixels then 2. Repair -> scanned documents.

However.

Going back to your printing question. Want to print DIN4 (A4) Your image cropped to A4 proportions is about 850 x 1275 pix @ 150 ppi Which gives a print size of 146mm x 215mm not A4 210mm x 297mm 

You could scale up to 210 mm wide but the image will still be 150 ppi - printing quality not so good. Resize again to 300 ppi which is good for printing and quality gets worse.

A better way is convert the image to a vector. There are on-line tools for this but I use linux. SVG is attached.



If you want to try this:

1. Open a new blank A4 image File -> New  and from the drop down template A4 this gives the correct size @ 300 ppi. Good for printing.
2. Import the SVG File -> Open as Layers with size in pixels as above. Remember Gimp is a raster editor and works in pixels
3. That’s it, add anything else as a new layer. Save your work as a Gimp .xcf When complete Export as a png or Tif for a printer.

[Delfin93]

[quote pid='6045' dateline='1517995552']
A better way is convert the image to a vector. There are on-line tools for this but I use linux. SVG is attached.
[/quote]

Allright! I googled it, but did not find an understandable answer to the question:

What is a Vector in GIMP?
And for what is the attached SVG-File?

Watched some turtorials on youtube, but somehow missed this part

Okay, I will try it out again with the PlugIn

Thanks!