How Do I Cut part out of an Image?

I've tried finding tutorials online for this, but no luck yet...

I'm looking to take part of existing maps and clean them up so I have good edges with everything outside the image proper as a transparency.

Specifically, I'm looking to take the images of the ships Icingdeath, Twinkle, and the Dreadnaught from Divine Contention maps and be able to take just the top level of the each ship and clean them up so that I can put them together in a new image to use for ship to ship combat. I've been able to trim out the parts of the images I want, but the edges are really poor (i.e. I have a bunch of the water with them). I think years ago I saw tools in Inkscape or Gimp to clean this up, but can't figure it out.

Help using either of those tools to clean up these images would be much appreciate. I've attached an example of part of one of the images that shows what I want to clean up.
Attachment 52333

https://www.educba.com/gimp-magic-wand-tool/

gimp magic wand will do the job. that will allow you to select the water and then delete it

As jharp says, the magic wand tool is the way to go in most image editing programs. It won't be perfect, given the wavy coloring of the water, and due to the grid lines, you'll likely have to click on each square separately to delete the water, but it should go much faster than zooming in and erasing along the ship's hull by hand. Here's an example of what your sample image looked like after just clicking once in each grid square using the magic wand and deleting the selected material:

Attachment 52335

You can see there is still some water that gets left behind, but most image editing programs also let you adjust the threshold or tolerance of the magic wand to be more or less aggressive in what it considers the "same" area. If you play with that it should make the process go a lot faster.

Cheers,
Brian

The other method is to block out the areas you want to remove with thick lines and shapes that are white or a lighter solid color. Add to remove, in a sense. Add shapes to cover the content you wish to remove and then use the wand.

Thanks all. Knew it should be simple :)

edit: with Gimp, using fuzzy select if you click and drag right it widens the selection criteria, allowing you to select more/larger spectrum of colors.

Don't forget in GIMP to go to the Layers Tab > Transparency > Add Alpha. Or something very similar to that. Then save it as a PNG. If you save it as a JPEG it will square everything and give you a white background. You should see the grayish checkerboard if it is transparent.

Edit: altering images without the grid is much easier, then re-add them in FGU. Otherwise scaling may change a bit, or objects may get moved and things won't line up anymore.

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Originally Posted by Max Silver

Don't forget in GIMP to go to the Layers Tab > Transparency > Add Alpha. Or something very similar to that. Then save it as a PNG. If you save it as a JPEG it will square everything and give you a white background. You should see the grayish checkerboard if it is transparent.

Edit: altering images without the grid is much easier, then re-add them in FGU. Otherwise scaling may change a bit, or objects may get moved and things won't line up anymore.

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Thanks, yea, and I do a fill of a color that is not otherwise used, and then do a Color to Alpha to turn the desired part of the image to alpha. Ended up only taking a few minutes to do the third/last ship.