Cropping coin images with GIMP - Tutorial

Usually, when I post a photo of a coin from my collection, it looks like this:


My goal is to have photos of this quality of every coin in my collection. Right now I have 2,652 similar photos saved to my hard drive, with a few hundred more to go. One photo takes less than one minute to assemble once I'm going at full speed. Some people ask about these photos, so here is how I put them together. (I use a Windows machine, so if you have a different operating system some of the advice here might not work.)

You will need

• Pictures of your coin. It doesn't matter what you take them with. Some people use cameras, I use a digital scanner. Many scans are small, grainy, and look like crap - but the newest scanners are quite high-quality. Try experimenting.
  
• GIMP image editing software. This program is absolutely free and it is about as good as Photoshop, so everybody with a working computer is able to use this. The download page is here.
  
• A computer.
  

Step 1. Open up your coin image in GIMP

With my flatbed scanner, I can image many coins at once, which is why I prefer this method to photography. If you have individual pictures, you will always be opening and closing new windows. But the method used to gain the image doesn't really matter.

Step 2. Pick the "circle select" tool

This is the circle select tool. It is your best friend. This tool does not exist in MS Paint which is why I made you download GIMP.

Step 3. Approximately select the area of your coin with the circle select tool

You do not need to get this exactly correct on your first selection. Just try to get it in the general area of the coin.

If your coin is not round, I don't know what to do. Usually I use a combination of several GIMP functions to crop photos of a non-round coin, which is a time-consuming pain.

Step 4. Zoom in close and make your circle as close to the coin's shape as possible.

Now you want accuracy. Move the dimensions of the circle until it matches the dimensions of the coin. If your mouse has a zooming wheel between the two buttons, you can hold down Control and use the wheel to zoom in and out quickly.

Step 5. Now that your coin is properly selected, copy it and open a new window with nothing but the coin in it.


There are key shortcuts you can press for this.
1. Ctrl + C will copy your selection.
2. Ctrl + Shift + V will open your selection in a new window.

If there are any hairs or dust pieces on your coin that you think are ugly, now is your chance to try and edit them out.

Step 6. Pick the "rotate" tool and rotate your image.


Most coin photographs are not perfectly rotated - especially those taken with a digital scanner. So now you can fix that. Select the rotation tool and rotate it however you want. I try to perfectly line up certain design features - in this case, the big, obvious horizontal line.

In my experience, you should change the rotation tool's "interpolation" setting to "Sinc (Lanczos3)". This changes how blurred the image will be after rotation. Try not to touch any of the other settings.

Step 7. Go into the "Layer>Transparency" menu and click "remove alpha channel".

This will remove the transparent background of your picture and replace it with a featureless white background.


More accurately, what this does is replace all transparent areas with the second colour you've selected here. So if the second colour inside the red circle I've drawn is not white, then you will not get a white background.


Here we are! If you prefer to keep separate images of both sides of a coin, you are done. Save your image and congratulate yourself. But if you want to put both coin images into one picture (as shown above), read on.

Step 8.Open up MS Paint. Do not close GIMP.

Now you have two image editors open at once. You'll see why.

Step 9. Paste your coin image from Step 7 into MS Paint.


Step 10. Extend your image to the right.

Click and drag that little square to extend your image space.

Step 11. Repeat steps 1 through 7, but for the other side of the coin.

This is why you left GIMP open! It will get faster with practice.

Step 12. Paste this second image into your MS Paint canvas and drag it over to the right.



Step 13. Crop your image
Click and drag that little square like you did in Step 10, but this time drag it to the left to remove the leftover empty white space.

Step 14. Enjoy!!

I recommend you save your images with the .jpg file extension, to keep their size on your hard drive small. I have more than 2,500 pictures in one folder, but they take up less than a gigabyte of file space. That means that you can easily fit your entire collection onto a thumb drive or SD card.

Yes, that is 14 steps to follow - but once you have practice they will go by in seconds. Having images of all of my coins has been very convenient for me, especially as I discover common coin types that I am still missing (because I would always think "that's so common I don't need to buy it...") and can easily tell if a coin that I am considering purchasing is in better condition than one I already own. Try it out!

Thank you, that's been a great help. I'm doing much the same thing but with Photoscape and without the skills. I wish I'd read this before starting on the project as it would have saved a lot of trial and error.

I've found that I get better results by rotating the coin before cropping it as there is some distortion, at least in Photoscape, when it's rotated.   

I'm storing the finished product on a 32gb thumb drive as the Florida climate isn't very friendly towards hard drives.

Any advice on how to best to capture images of coins in 2x2s? Taking them out isn't an option because I'm using the self sealing types and printed labels for my British collection which is the one I really want to photograph..

Quote: pnightingaleAny advice on how to best to capture images of coins in 2x2s? Taking them out isn't an option because I'm using the self sealing types and printed labels for my British collection which is the one I really want to photograph..

With 2x2s I find that a scanner works, but only some of the time.

A scanner gets great images when it's imaging something pressed right up to the scanning surface, but anything even a millimeter away from that surface will become blurred and distorted, so a scanner is totally useless for slabs and thick hard plastic containers. However, the thin plastic film in a 2x2 will usually not disrupt the scanning process - usually. A large, thick coin will press right up against the scanning surface and everything will work out fine - however, a small coin may not be thicker than the cardboard 2x2 that surrounds it, leading to blurry scans. I have found no remedy for this but to pop the smaller coins out of their holders, but if your collection is mostly pennies and crowns then you should be all right.

Does GIMP take along time to startup? I have been waiting about 5 minutes, and all I have is the GIMP startup tab.

That's not normal it should load fairly quick. I also use gimp I love it but it can be frustrating. I also use inkscape the combination rocks.

I use several programs but the easiest 2 I have used is Xara Xtreme and Irfanview for cropping/resize/enhancing/DPi/sharpening etc. etc. I have others but they are a lot more complex and would only serve as a headache to those unfamiliar.

Nice little tutorial for those who are not too image editing savvy with Gimp.

Numisdoc material?

Hey Phil.  Yes so much info. has gone through the forums that should be in numisdoc. It is not funny. Even if in numisdoc there are only links to the form it would be nice.

Quote: pnightingaleNumisdoc material?

Needs to be pinned to the top at least.  

Use PowerPoint and make it a slide  --------dead simple

Thanks for this.

Being a co-referee for Canadian Colonials, I really needed this skill. Only took me 3 hours (and about as many beers!!).

But, the first one is up.....https://en.numista.com/catalogue/pieces96406.html
I think I did reasonably well.

Quote: "ALLRED1950"​ Hey Phil. Yes so much info. has gone through the forums that should be in numisdoc. It is not funny. Even if in numisdoc there are only links to the form it would be nice.

​I agree. Being a bit eager I spend a lot of time searching keywords in the forum search, and I get so many great threads that I think would be great for a lot of little scrubs like myself to read. I've also personally shown a couple of newer or less technologically-inclined members that search function, so I'm willing to bet there are a few people out there who wouldn't know how to find 6 year old threads with great info.

Is there a Numisdoc referee or anyone like that? If not then I think maybe there should be someone dedicated to editing or linking threads to Numisdoc.

Hi Nalaberong,
That was an excellent easy to understand tutorial on aspiring to get a perfect coin image.
Will try it out later.
regards

https://en.numista.com/numisdoc/pictures-and-images-on-numista-141.html