Using GiMP to Resize Photographs

GiMP is a powerful open source tool which can be used to advanced photo editing and manipulation. This is the first in our series of guides to using GiMP. Many people ask me how to resize their photos to smaller sizes for emailing or even submitting to ZooFoo. GiMP makes this a very quick and easy task to complete.

1. Open the File

The first step is to open the file in GiMP. With GiMP open access the File Menu in the upper right corner of the window. Select "Open" and then browse until you find the file you wish to resize.

2.Scale the Image

Now that the image has been opened the next step is to access the Image menu and select "Scale Image".

3. Change image Size

After clicking "Scale Image you will be brought to a dialog box with various options for how you would like to scale the image. While this may seem confusing at first you only really need to be familiar using a few options to be successful. Specifically the Width and Height Settings. You will see the current width and height settings for your image. Next to these numbers you will see a small icon that looks like a piece of chain. This means that the image sizes are linked together in the ratio of the original image. If you change one of the numbers - say type 1024 in place of 2048 - GiMP will automatically change the other number to keep the dimensions of the image proporational. This is very handy because it means you only have to know or specify one dimension to resize the whole picture. After you have changed the image size to the desired size click the "Scale" button to save your changes. If you made a mistake click "Reset" or "Cancel".

4. Understand Scaling Options

Once you have mastered changing the size with locked ratio pixel counts you can begin to experiment with some of the other options. If you want to approach the image from a different scale other than pixels click the word "pixels" and a drop down menus will appear letting you choose the units for viewing the Image Size.

Below the Width and Height there is the X and Y resolution. This number is how many pixels will be shown per unit of either dimension. The default is DPI (dots per inch). This is relative to the pixel count so for example a 1000 pixel wide image at 100 DPI will be considered 10 inches wide. If you shrink the pixels to 500 but leave the DPI at 100 the image will now be considered 5 inches wide. On the other hand if you leave the X width at 1000 and change the DPI to 50 pixels/inch you the image will now have a width of 20 inches.

The quality setting options are none, cubic, linear or Sinc (Lanczos3). These settings define how the image will select which pixels or sections of the image to remove as the image is rescaled. Different types of interpolation have different effects on the image and its relative size. I would recommend experimenting with these to learn which is best for you.

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