Using GIMP for Quick and Dirty Image Editing

In other posts I placed in this blog, you will notice I drew crude arrows and added text to screenshots (i.e., pictures I took of my computer screen). The software tool I used to do this is called GIMP (GNU Image Manipulation Program). GIMP is a free, open source program that is similar to Adobe Photoshop. There are versions of GIMP that run on many operating systems, not just Windows.

GIMP can be downloaded for free from the following address: www.gimp.org.

The same tool and procedures can also be used to prepare photos for use in a computer-based lesson. I will use a photo I took at the beach on Assateague Island to step you through the basic process using the Windows Vista version of Gimp.

(1) Before anything else, copy your original photo to another folder on your computer and edit your copy. This will protect you from accidentally damaging or destroying your original.

Navigate to the folder where you saved the copy and place the cursor over the file. Note the format in the little window that pops up. Most likely, it will be in JPEG format.






















(JPEG is what is called a "lossy format." For a description of lossy vs. lossless formats and other useful stuff, go to the resource sheet I created as a companion to my ProLiteracy/Verizon Thinkfinity Podcasts. You will find the page at this address: http://literacynetwork.verizon.org/tln/files/techinst.pdf.)

(Note: To view a larger version of any of the images in this post, left click on it and it will appear in the browser. Left click on the browser's back button to return to this post.)


(2) Make sure you have installed GIMP. In the same folder, right click on the file and left click on "Edit with Gimp" in the menu that appears.

























(3) GIMP will automatically open. At the left you will find the "Toolbox," which contains icons for various tools that can be used in editing an image. At the right is a panel with additional options. In the center is the workspace, containing the picture you will be editing.
















In this tutorial, we will be concerning ourselves only with the workspace and a couple of tools in the Toolbox.

(4) For our lesson, we would like to use only the center portion of the picture and trim off the outer edges.


















(5) To do this,

(a) left click on "Tools" in the workspace toolbar,

(b) left click on "Transform Tools" in the menu that appears and

(c) left click on "Crop" in the next menu.





















You can also press Shift+C on your keyboard to do this.


(6) Now, in the image you wish to crop, left click on one of the corners of the section you would like to "cut out" and, while holding down the left mouse button, drag the cursor to create a rectangle or square that outlines the area you wish to keep.






















(7) When you are done, release the left mouse button and the area that will be removed will appear shaded.






















Simply press "Enter" on your keyboard to cut out the image.

(8) The shaded portion will now be removed from the image.






















(9) To draw crude arrows, left click on the "Pencil Tool" in the toolbox.



























(10) In the workspace, left click where you would like the line to begin in the image and, while holding the left mouse button down, drag the cursor to draw your line. Release the left mouse button when you are finished.






















(11) If you make a mistake and would like to "erase" a line:

(a) left click on "Edit" in the workspace toolbar and

(b) left click on "Undo Pencil" in the menu.























(12) Now, the last line you drew with the Pencil Tool will disappear from the image.


















(13) To add text, left click on the "Text Tool" in the toolbox.




























(14) A section will appear below the Text Tool which will allow you to increase the font size, if you'd like.



























(15) Place the cursor where you'd like it to appear in the image and press the left mouse key.





















(16) A little "GIMP Text Editor" window will pop up. Type your text in the text editor. The text will simultaneously appear in the image.






















Left click on "Close" in the text editor when you are done. You will now see the image with the test included.






















(17) Now, you are ready to save the image. To overwrite the version in your file (this is why you should always work with a copy of your original in a different folder instead of the original itself), left click on"File" in the workspace toolbar and then left click on "Save" in the menu.






















Left clicking on replace in the next menu will overwrite your original.





















To save a copy, follow the instructions for "Save As" that follow this segment of the tutorial.


(18) If you get a message like this, left click on "Export."






















(19) Because the quality of a JPEG (lossy format) image degrades each time you edit it, you should save a copy in a lossless format, such as PNG, if you wish to continue editing the image at a later time.

To do this:

(a) left click on "File" in the workspace toolbar and

(b) left click on "Save As . . ." in the menu.






















(20) In the next menu:

(a) left click on "Select File Type,"

(b) left click on "PNG image" in the list of formats that appears and

(c) left click on "Save."























(21) In the next menu, left click on "Export."






















(22) Next, click on "Save."





















(23) A green progress bar will show you the status of the conversion and save.





















(24) Now, when you view the picture in a photo viewer, it will look like this:


















Notes:

(1) When converting from PNG to JPEG, GIMP will usually recommend a picture quality of 85%. This should be sufficient for most purposes. The difference between 85% and 100% is not noticeable and the higher quality increases the size of the file dramatically.

(2) If you are beginning with a JPEG file and you plan to do a lot of editing over several sessions, convert the JPEG image to PNG and edit that. Save the edited image back to JPEG format when you are done.

(3) You can also use Microsoft Paint to draw simple lines and add text to an image and to change the format, but you can't crop it with this tool. I like to crop the image at the same time I'm adding arrows and text because sometimes I need to add a little more real estate than I originally thought to make room for text. With GIMP, I can use the undo option to go back a few steps and resize the image without having to go to another tool. This is my preference. Whatever works best for you is the best way to do it.

(4) Another reason I prefer using open source, multi-platform tools like GIMP is they run on multiple operating systems while proprietary packages generally work on only one. At various times I will work on computers running Windows, Linux and UNIX. Because tools like GIMP work on all three operating systems, I don't have to make any adjustments when I switch between them, so it doesn't matter which one I am using.

This is also applicable to computer-literate learners. They do not need to buy a state-of-the-art computer to use these tools. Any old computer that can run Linux or UNIX at a reasonable speed will do. Moreover, any materials created under one operating system with these tools can be used or edited on another computer running a different operating system.