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Sope 28. Aug 2015 06:33 PM

Remove hand written notes (pen/pencil marks) from scanned document
I'm looking for a program that would enable me to automatically remove the hand written notes from a scanned copy of a document.

Basically the scanned page is of black printed text but has a lot of handwritten blue pen markings scattered over it, underlining and circling words etc.
It's proving a very difficult and labourious task to try to remove them using PDF-XChange Editor!

So I was wondering if there's a program out there that would allow me to selectively remove a particular colour from a scanned document i.e. blue pen ink!
Perhaps if I scanned it in another format and used a graphics editor such as GIMP? Unfortunately I'm not familiar enough with using GIMP to know how to go about it or if it's even possible?

Any suggestions appreciated :)

torres-no-tan-magnifico 28. Aug 2015 07:07 PM

I don't have GIMP but most image editors have an erase tool, which will remove the offending blue ink marks. Presumably, the background colour of the document is white and therefore, this shouldn't cause any further problems.

You will of course have to save the document as either a PNG or JPEG etc.

Good luck!

Anupam 28. Aug 2015 07:32 PM

Yes, even basic photo editing software will have an erase feature. I use small photo editing software to make minor edits on images. Photoshop or Gimp are heavy software, and I don't feel the need for such complicated software. I personally like Hornil StylePix free:

It has an erase feature.

Only thing is, as Torres says, if the background will be white, then it will be good... because erasing something will leave a white space behind, so if it's a white background, then it will look alright.

sicknero 28. Aug 2015 11:20 PM

It might be worth you looking into GIMP ... it has a variety of selection tools that could save you a lot of time, eg select by colour. Again though this would require you to first convert the pdf to an image format.

There's a Paf version on John Haller's site, so you can test drive it without installing anything.

Joe A.TT 29. Aug 2015 12:08 AM

Most better image editing programs have a feature which allows you to swap one color for another. However, I should warn you that it is not going to be a simple job. One factor that could make the job more difficult is if the writing is in varying shades of blue. I am almost certain that is the case but you could confirm this yourself by zooming in to the writing and inspecting it closely.

The best program I can think of for the job is PhotoFiltre 7. It has an advantage over GIMP in that its "Replace color" function incorporates a Tolerance slider (see screenshot below) which could be handy when replacing varying shades of the same color. Also, depending on how thorough or neat you want to be, you may need to paint and touch up here and there with the background color afterwards.

There is a portable flavor of PhotoFiltre 7 so you don't even have to install it.

Sope 29. Aug 2015 10:26 AM

Thanks guys.

I believe using the eraser tool in most of these programs is a manual process which I was hoping to avoid resorting to as the amount of pen marks, and how close they are to the original text is going to make it a painstaking job!
I did start the process in PDF-XChange Editor using a high zoom and the pencil tool set to white, and that's what got me hoping for an automated alternative method!

I've had a play with GIMPPortable and found the "select color" tool, although as Joe mentions, the varying shades of blue are an issue. GIMP does have a threshold/tolerance slider but it's not an easy thing to get right, and I made a bit of a mess with that.

I'll have a look at PhotoFiltre and see if that's any more user friendly. (Good to hear there's a portable version).


sicknero 29. Aug 2015 10:45 AM

How about approaching it from the other direction?

I.e. Select all black, then Invert Selection.

Sope 29. Aug 2015 11:08 AM


Originally Posted by sicknero (Post 113814)
How about approaching it from the other direction?

I.e. Select all black, then Invert Selection.

Good idea!
I like the lateral thinking.
Thanks :)

Sope 29. Aug 2015 12:06 PM


For anyone interested, here's how I did it....

1. Export PDF to BMP using PDF-XChange Editor.

2. Open BMP in PhotoFiltre and use the "replace color" tool to select offending blue pixels and replace them with white.

The replace color tool took a bit of finding and playing about with but it simplified the task enormously.
Basically the process was.....

> zoom in to 500%
> selection menu > select all
> adjust menu > replace color
> use color picker to select colored pixels (blue in my case) to be replaced
> adjust tolerance level to achieve maximum desired effect being careful to avoid inclusion of original text pixels
> replace selected pixels with white (in my case)
> repeat color selection for remaining blue pixels that were out of tolerance range of initial selection
> again replace these remaining selected pixels with white
> repeat until no blue pixels remain

3. Save the edited BMP and print to PDF using doPDF 8

et voila!

For me, PhotoFiltre's "replace color" tool was easier and more efficient than using GIMP's combination of select color and color fill tools.

Thanks for the input everyone. :)

Joe A.TT 29. Aug 2015 01:25 PM

GIMP is awesome and it's my main image editor but, as you've discovered, some things can be done much easier in PhotoFiltre. Nice to know it worked for you. :)

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