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I need to straighten (turning clockwise or counterclockwise, 1 or 2 degrees) several pictures of the same place taken during different months of the year. I took them standing on the same spot but because I did not use a tripod there are some -minor- angle differences.

Is it possible to have a visible squared grid while straightening and cropping on Digikam, gThumb, Shotwell, nomacs or Gwenview?

I want to crop them to squares and I think this very simple method will give me the result I am looking for.

BobT
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c8h10n4o2montreal
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  • The title of your question isn’t accurate. The question really is about rotating using a grid. – Eric S Nov 25 '19 at 13:04
  • You can try XNView MP (available for Linux) where you have grid but you should use slider or enter direct the number – Romeo Ninov Nov 26 '19 at 15:34

2 Answers2

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I'd recommend darktable for this: see the Crop and rotate module, which has a grid under the 'guides' option.

However, note that with darktable there's a potentially better way of doing what you need to do: you can rotate to a desired reference line by "drawing" that line on the photo. To quote the manual:

To use your mouse, right-click, hold it down and draw a line along a suited horizontal or vertical feature; as soon as you release the mouse button the image is rotated so the line you drew matches the horizontal/vertical axis.

Kahovius
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Digikam

The "Free rotation" tool has an "automatic adjust" option.

Gimp

You can use the "Rotate" tool in "corrective" mode, and tell it to display various patterns of lines that you align on things that should be vertical/horizontal.

In Gimp 2.10, you can also use the "Measure" tool and measure the angle of something that should be vertical/horizontal, and then click the "Straighten" button to straighten the image.

xenoid
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