Converting Image Files with GIMP
What is the GIMP
The GIMP, or GNU Image Manipulation Program, is a free image editor and creator. It offers many of the same features as Adobe Photoshop and is a very powerful tool for creating, editing, and converting digital images. This is a free program, which has been around for over 10 years.
A Brief Introduction to Digital Image Files
If you have ever dealt with digital images, you might have noticed that there are many different formats. The easiest way to tell the format of a digital image is to look at the extension of the file.
One of the most common digital images is the JPEG. A JPEG file usually ends in "jpg", although it can also end in "jpeg".
JPEG stands for Joint Photographic Experts Group and is designed to conserve space. This is probably the most popular format for use online because of its low size.
However, this low size comes at the cost of quality, which is why JPEG is referred to as a lossy format. Also, if you are using a photo manipulation program, like The Gimp, and have created several layers, you won't be able to edit these layers after you save it as a JPEG.
GIF, or Graphics Interchange Format, is another popular online format. It only allows 256 colors, but it allows you to create animated images.
PNG, or Portable Network Graphics, images was created as a successor to GIF images, however, it can support up to 16 million different colors, where a GIF can only support up to 256. PNG is a lossless format, so it is great for creating images, but most people will convert the image to a JPEG when they are ready to distribute it. This is because a JPEG file is compressed and therefore smaller than a PNG.
These are just a few of the many image file formats you might come across.
Converting the Image
Converting Images Using the GIMP is actually as easy as using the "Save As" File Menu Option.
However, it is necessary, at least on Linux, to add the extension to the filename. Don't worry if you don't know the extensions, because they are all displayed by the GIMP.
- Open the Image File
- Goto the File Menu and Select "Save As"
- Enter the new file name and extension.
- If you are unsure of the extension, click on the drop down box that says "All Images." Select the format and you will see the extension.*
- Click Save
* For instance for JPEG it says "JPEG Image (*.jpg, *.jpeg, *.jpe.)The extension is the part after the *.
Some Notes About JPEGS
If you are converting from a lossless file format, like PNG, to a lossy file format, like JPEG, The Gimp will pop up and ask you what quality to save the image as. You can select 100% or if you want to save space, select a lower quality, with the default being 85%. The lower the quality, the smaller the file size, but be careful,because it also means the image will not look as nice. Click on the "Show Image in Preview Window" check box to see how the quality will affect the image.
If you have created an image with multiple layers, The Gimp will warn you that it must flatten the image and export it. This is because JPEG can not handle multiple layers. For instance if you added some text to the image and then save it as a JPEG, you will not be able to edit the text again. This is why most people will save it in a lossless format, like PNG or Gimp Image Files (*.xcf,) first. Then save it in JPEG format. This way if you need to go back and edit the image, you can still do so.