Editing images with Gimp.

Disclaimer!  This Is not intended to be a tutorial on how to use Gimp in all its glory – it is intended to show you how to perform the specific steps needed to transform a master image into a web-ready image hosted on The People’s Collection Wales website.

This page contains the following sections.

  1. Installing and opening Gimp.

  2. Importing images.

  3. Rotating images.

  4. Changing perspective.

  5. Cropping images.

  6. Resizing images.

  7. Obscuring personal details.

  8. Inserting borders.

  9. Inserting a logo.

  10. Exporting images.

  11. Merging images.

  12. Keyboard shortcuts.

Download Editing Images with Gimp.

1. Installing And Opening Gimp

Download and install the latest version of Gimp from https://www.gimp.org/

Start Gimp – this can take a while! When you start, everything will look confusing - do not panic, take a deep breath.

When you first open Gimp, you should see something like this –

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There are 2 ways to interact with Gimp—multiple window mode, and single window mode. You can switch between them by going to the Menu Bar > Windows > Single Window Mode. Unless you are working with two images at the same time, e.g. to merge them, I suggest you use Single Window Mode (make sure the box has a cross in it). 


2. Importing Images Into Gimp

If you have a large enough screen then as well as having Gimp open, you can open the folder containing the images you wish to edit. You can click and drag an image directly into Gimp.

If you do not have enough room on screen to open the folder, then on the Menu Bar go to File > Open, and navigate to the folder containing the images, and open the one you require.


3. Rotating Images In Gimp

Does the image require straightening? I.e. is it leaning to the right or left?

If so, select the Rotate Tool

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from the Toolbox and click on the image.

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You can also drag down guides from the top ruler. You can drag as many guides as you require.

If you want to get rid of a guide, select the Move Tool from the

Toolbox, click on the

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guideline (it should turn red), and you can then drag it off the workspace. Alternatively, go to the Menu Bar > View > Show Guides and uncheck the box (you will have to turn it back on again if you want to use guides again in the same session).


4. Changing Perspective

Sometimes, especially when digitising photographs, you are working with images shot from above or below, or one side.  Whilst the original master image should never be manipulated, it is permissible to edit an image destined to be published on the web, to make it more closely resemble the actual object itself.

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Select the Perspective Tool 

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from the Toolbox and click on the image.

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Remove the guidelines to make the workspace clearer.


5. Cropping Images In Gimp

Select the Crop Tool 

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from the Toolbox and click on the image.

Use the Crop Tool to cut away any part of the original image that is not part of the object itself (in the case of photographs of objects, leave a narrow border around the object, if you are digitising the whole photograph and it has a border, keep the border).

Position your cursor on the corner of the image where you want to start the crop and click and drag diagonally to where you want the crop to end. Release the mouse button (if you are using a mouse!)


You can now commit to the crop by clicking inside the crop box or abandon it and start again by clicking outside it. 


6. Scaling (Resizing) Images In Gimp

Go to the Menu Bar and select Image > Scale Image.

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7. Obscuring Personal Details in Gimp

When you are editing documents such as letters , etc. you may want to obscure personal details before the image is published on the web. These may include, but not be limited to, address, telephone number, fax number, and email address. JHASW does this if the image is less than 50 years old.

To do this we use the Smudge Tool

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It is simpler to Smudge after resizing, and before inserting the border or logo.

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8. Inserting A Border In Gimp

Go to the Menu Bar and select Filters > Décor > Add Border

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Once you have changed the Border defaults, they will stay in force for the active Gimp session.  If you close Gimp and re-open it, next time you insert a border you will have to reset the parameters to the required settings.


At this point you should check that there is a clean line between the edge of the image and the border.  If there is a gap, or void, you may want to undo the Border (press Ctrl+Z) and re-do the Crop, and then re-do the Border.

To see the resized image more clearly, you can zoom in and out using the plus and minus keys on the keyboard.

9. Inserting And Positioning A Logo

This works far better if you copy the logo to your desktop as then you can just click and drag it onto the image in Gimp (if you are working in full screen, you will have to resize Gimp so that the logo is visible).


Only insert your organisation’s logo into images for which you own the copyright.

The logo will automatically be placed in the centre of the image. JHASW positions it in the bottom right hand corner.

Double click on the Alignment Tool

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and a new dialogue box will appear.

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10. Exporting The Image From Gimp

Go to the Menu Bar and select File > Export As.

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In the Close dialogue box, select Discard Changes as you have already saved a jpg version of the image and do not want to change the master.


11. Merging Images in Gimp

There may be instances where the document you are digitising is too large to be scanned in one pass.  In these cases, it may be necessary to scan the document in parts and digitally stitch them together afterwards.

The example here shows how to join two images together, but the same process can be used to join more. 

Wherever possible try to retain the same orientation of the document on the scanner as this reduces potential tone differences from light leaking into the scanner from the side.


This process is easier if you use Gimp in non-Single Window mode. You can toggle this on and off in the Menu Bar by going to  > Windows > Single Window Mode.  The box needs to be checked.


The following instructions assume that you are already familiar with basic Gimp processes such as Rotate, Crop etc.

Select both images and drag them into Gimp.

You should be able to see thumbnails of both images in the top left of the workspace. You can toggle between the two by clicking on them.

It makes life easier if both images are straight, so sort this out before you do anything else.


Decide which image is going to be the main one and click on the second to start editing it.


Before you select the area you need to copy, have a think about how easy it is going to be to line this up with the other part of the document.  It may be easier to position the edge of your crop in a part of the page where there is no text, or along a pre-existing line on the document.  If this is not possible then try to place the crop mark so that it crosses as little text as possible.


Using the Crop tool, select which part of the second image you will need to copy, and when you are happy with the selection, click inside it to finalise it.  Copy it to the clipboard by pressing Ctrl+C.


Toggle to the other image.

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12. Keyboard Shortcuts and Tips for Gimp

If you are happy to use keyboard shortcuts, some of which are built into Gimp and some of which you can create yourself, then some of these processes can be completed a lot faster; this is particularly true if you are performing the same processes on a batch of images.

On the Menus Bar select File > Keyboard shortcuts.

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As usual Ctrl+Z undoes the last action, and Ctrl+Y re-does the last action.

Using keyboard shortcuts may seem fiddly at first, but once you get used to it, it can significantly speed up part of the editing process (especially if you are not using a mouse).

Creating shortcuts for File > Export As; and Image > Scale Image, is useful – I use Ctrl+X and Ctrl+S


E.g. to resize a portrait image, Ctrl+S > Tab > Tab > enter 1300 in the Height box > Tab > Tab> enter 72 in the X Resolution box > Return > Alt+S

Ctrl+F will repeat the last special action, e.g. inserting a border, so if you inserted a border on the last image you worked on and haven’t executed any special action since, Ctrl+F will now insert a border.


E.g. to export a file, Ctrl+X > double click on your destination folder > do the backspacing to change the filename extension > Return > wait for the other dialogue box to open and Return again.