Problems with straightening chronicle image

Hello. I have photos of my school chronicle and I need to straighten those, because they were made not at a perfect right angle. Also paper was not perfectly flat and it creates more curves. I tried to use cage transformation and manually stretch images but it took like 1 hour for 1 image (most of the time I waited for my computer to process it). Is there some better, faster way to deal with it? I thought about using paths to mark all the curves and then straighten those with some tool but I couldn’t find anything like that. Thank you in advance for help and sorry if this topic where somewhere else already.
PS: I couldn’t use scanner, because chronicle is too big :slight_smile:

Hi @Bartlomiej_Baran and welcome!

So they are out of perspective, so to speak.
Do they all have the same degree of “out-of-perspectiveness”,
or are they all unique?

Might this be of assistance: Distorting -- IM v6 Examples?

Have fun!
Claes in Lund, Sweden

They are all unique sadly. And also the paper wasn’t flat so each page is even more unique.

And about the link, it looks like this page describes how to calculate things like this, so as far as I understand, this is only helpful when you want to program tools. And I would want some already made tools, because my programming skills are… in progress let’s say.

I basicly try to make photographed book’s pages make look good, so they can be used to publish on our school website or even at wikimedia commons, because I believe they have even historical value.

PM sent…

If you shoot the paper at an angle, the proper tool to straiten things is the Perspective tool used in “corrective” mode. In that mode you align the handles/guides with things that should be vertical/horizontal and Gimp computes reverse perspective transform for you. However this doesn’t not produce the actual aspect ratio, so you may have to scale the result along one dimension, and you’ll have to find the real aspect ration first (known paper format or else).

To straighten the curves, you can have some luck with Filters > Distorts > Curve bend as a second step. However this filter seriously blurs text.

Maybe it is possible to scan each of the pages in two runs and then stitch them together? I had quite good results with Microsoft’s ICE. Hugin sure can do this too.
How big is this chronicle btw?

Sorry for keeping you waiting. It is longer and wider than A4. And also it would be really hard to make those scans flat especially at place when all the pages are sticked together.

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I have devised fairly simple methods for:

Straightening horizons – distorting an image so an arbitrary line becomes straight and horizontal.

Straightening two lines – distorting an image so two arbitrary lines becomes straight and horizontal and parallel to each other.

The “arbitrary lines” can be drawn by hand over a copy of the image with Gimp, or created automatically for example from edges of a photographed page.

The methods can be combined. For example, we can make two opposite sides of a photographed page straight and parallel, and repeat for the other two sides.

The methods use Imagemagick, in Windows BAT scripts. The scripts could be converted to bash or other languages. An enterprising person could convert them to G’MIC commands.

Didn’t read all of the replies so sorry if this has been mentioned.
If your images are only out of perspective you could use a grid then perspective tool