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Author Topic: Help With Gimp  (Read 902 times)

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Offline Schatz

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Help With Gimp
« on: November 28, 2020, 11:16:58 am »

Hi everyone,

are any of you using Gimp 2.10.22 to stitch the images of your coin obverses and reverses together into one image?

I had to trash my 2009 iMac and get a new one.  This was necessary but painful because the old one contained 2 apps I had been using for my photo editing and stitching and felt very comfortable with but they were no longer supported by the new OS (Big Sur).  So I downloaded Gimp because it is supposed to be so intuitive.  Well, my intuition does not work here, and I have been watching YouTube tutorials ad nauseam.  None of my picture names are recognizable on Gimp, the picture menus when I click 'open' in File are totally incomplete and the pictures unidentifiable by name.  It almost seems as if Gimp is not properly connected to my Picture Library on my new Mac.  Of course, during the manual data transfer from my old computer to the new one several files were lost, and I am now struggling to retrieve those. This is the mess I had anticipated but the computer replacement had become inevitable.  Still, I need to go on stitching and will have to become familiar with Gimp whether I like it or not.  Can anyone help and give simple instructions on how to handle this?  I would be eternally grateful.

At a loss,
Schatz

Offline dwarf

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Re: Help With Gimp
« Reply #1 on: November 28, 2020, 11:42:21 am »
Two annotations:
First: There are some nice downloads by Ulrich Werz on academia.eu as to photographing of coins.
Helped me a lot - but (only) in German
https://niedersachsen.academia.edu/UlrichWerz


Second: I struggled with Gimp, too, and decided to invest 100 Euro and bought Adobe photoshop elements.
It made some tedious tasks very simple.

I am happy with a combination of both, using InfranView when neccessary and especially digiCamControl with my camera

Regards
Klaus

Offline Heliodromus

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Re: Help With Gimp
« Reply #2 on: November 28, 2020, 04:51:16 pm »
I use GIMP, but on Linux rather than on a Mac, so it may not be exactly the same. I'm guessing that your filename issues are something Mac-specific, so you may need to look on Mac forums for a solution.

There's more than one way you could choose to stitch two (obv, rev) images together. The way I do it (fewest steps) is to increase the width of the obverse image to make room, then paste the reverse image there (the alternative would be to create a brand new canvas of right size, and copy both obv and rev there).

1) Load both images into GIMP (either select both then open with GIMP, or alternatively run GIMP then use File->Open to open each one)

2) We're going to double the width of the obverse image to make room for obv+rev, not just obv:

a) In obverse image window, select Image->Canvas Size

b) In the canvas size pop-up window, double the number in the "Width:" field (e.g. if it is currently 1000, change it to 2000, or larger if you want more room to play with), then click the "Resize" button at bottom of the window

c) The image (or technically "canvas" - the area the image is displayed on) has been resized, so now use your normal Mac window resize controls to expand the window to see the extra space you have created. The extra space will show up as a checkerboard pattern indicating it is transparent, which is fine. If you find it offputting, you can use Image->Flatten Image to change it from transparent to your background color.

3) You're now going to copy the reverse image and paste it into the (expanded) obverse image:

a) In reverse image window, from Tools->Selection Tools menu, click on "Rectangle Select"

b) From Edit menu, click on "Copy"

c) Switch to obverse image window, and from Edit menu click on "Paste"

d) By holding left mouse button down and dragging mouse you can now position the pasted image to where you want it

e) One you've positioned the pasted image, left click anywhere on the image to finalize the placement (but you can always go back with Edit->Undo)

4) Now you'll save the stitched image with a new filename:

From File menu select "Export As" and enter a name with a file extension of the type you want to save it as (e.g. "coin.jpg" to save as a JPEG image, or "coin.png" to save as a PNG image), then click "Export" at bottom of window. You're done!

It sounds like a lot of steps, but really only takes a few seconds once you've done it a few times.

Once you're comfortable with this basic process, there are a few other things you are likely going to want to do, such as:

- maybe reposition the obverse image before you paste the reverse image (I usually move it to top left corner to make final crop selection faster)
- perhaps select/copy only a portion of the reverse image (the coin itself, not the entire image which may have too much background)
- crop the stitched image before you save it to remove any excess borders
- maybe rotate obverse or reverse to get them nicely upright
- maybe resize reverse to match obverse (or vice versa) if they are not the same size (maybe you took them hand held, or they are eBay images)

You would do any obverse image repositioning, or more fine controlled partial reverse image selection, as part of step 3 above, after having selected "Rectangle Select". e.g. To only select part of the reverse image you would left click and drag to select (rectangular) portion of the image before doing Edit->Copy. To reposition the obverse image beforehand you'd just select a portion of it in same way and do an additional Edit->Copy, Edit->Paste to position it.

To crop the image (get rid of excess borders) before saving it, select Tools->Transform Tools->Crop, move the edges/corners of the selection box to what you want to keep, then click in middle of the selection to do the crop.

Sometimes when saving the image, it may be more convenient to use File->Overwrite to overwrite the obverse image (assuming you don't want to save it) rather than File->Export As to specify a new name/folder.

Try this out and see how it goes - if you want to know more about image rotating or resizing, just post again.

Ben

Offline Schatz

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Re: Help With Gimp
« Reply #3 on: November 28, 2020, 05:08:03 pm »
Hi Ben,

thank you so much for taking the time to give those detailed instructions.  I was on the verge of giving up especially since I saw the sale price of PE 2021 online.  Now I am encouraged to try again.  I do not necessarily need the drop down menu of the 'open' function in File to get one of my pictures on the Gimp screen, all I have to do is drag it from the Photos app on the Mac over the Gimp icon in the dock.  But then the problems start: I resize the image, expand the canvas to accommodate the reverse image but I somehow cannot merge the two, one always disappears even if I click on 'merge layers' .  This is the status of my experiments.  I will go through your instructions religiously and hold off on my acquisition of PE 2021.

Again, thanks for your help and all the best,
Schatz

Offline Heliodromus

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Re: Help With Gimp
« Reply #4 on: November 28, 2020, 05:21:16 pm »
Hi Schatz,
Image->Merge in GIMP is probably not the most intuitive name! It's not used for merging images, but rather for merging "layers". For some GIMP operations, your image may consist of multiple semi-transparent "layers" all stacked on top of each other, and "Image->Merge" is used to collapse multiple of these layers into a single layer.

In GIMP-speak stitching images together is really a copy-and-paste operation, not a merge!

Regards,
Ben

Offline cmcdon0923

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Re: Help With Gimp
« Reply #5 on: November 29, 2020, 01:22:13 am »
I've never used GIMP, but if your main requirement is stitching together images, PhotoScape has a good and easy to use tool.  It's also good for cropping and color/brightness changes.

And best of all, it's FREE.

According to their website, they have a MAC version, too.  I run it on a PC, but I assume the MAC version should be much the same in functionality.


http://www.photoscape.org/ps/main/index.php



Craig

Offline Schatz

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Re: Help With Gimp
« Reply #6 on: November 29, 2020, 10:35:26 am »
Hi, Craig, Ben, and Klaus,

it worked!  l used Ben's step-by-step instructions and realized how similar to my old PE6 procedure the Gimp stitching is.  Where I got stuck before was the addition of the reverse image after the expansion of the obverse canvas. I thought I had to start creating layers - should not have watched the YouTube tutorials where they are layering all the time. Now I will have to do a batch of coins just to develop a routine.

The trouble with the image identification after I click 'open' in File is that apparently, and for whatever reason, Gimp is using the iCloud descriptions of my pictures although I never put them in the cloud as far as I remember. 

Thanks to all of you again, I did read the 2 Werz articles I downloaded from Klaus' message and will try out the photo app Craig recommended, just out of curiosity.

All the best to you,
Schatz

 

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