How do I change the size of an imported image in GIMP?

To change the size of an imported image in GIMP, you need to use the "Scale Image" function. Here's how:

1. Open the Image: In GIMP, go to File > Open and select the image you want to resize.

2. Access Scale Image: Go to Image > Scale Image. This will open the "Scale Image" dialog box.

3. Adjust Image Size: In the "Scale Image" dialog box, you'll find options to change the width and height of the image.

   • Units: The default unit is pixels. You can change this to inches, millimeters, points, etc., using the dropdown menu next to the width and height values. This is useful for specifying a desired print size.

   • Width and Height: Enter the new desired width and height values.

   • Chain Icon (Keep Aspect Ratio): By default, a chain icon links the width and height values. This means that when you change one value, the other will automatically adjust to maintain the image's original aspect ratio. If you want to distort the image, click the chain icon to unlink the width and height before entering new values.

   • Resolution (X and Y Resolution): This controls the image's pixels per inch (PPI) or pixels per centimeter (PPCM). Increasing the resolution can improve print quality, but it doesn't inherently change the image size displayed on the screen. You can typically leave this at the default value unless you have specific printing requirements.

4. Interpolation: The "Interpolation" dropdown determines the algorithm GIMP uses to calculate the new pixel values when resizing.

   • Lanczos (Sinc): Generally considered the best for most resizing tasks as it provides good quality while minimizing artifacts.
   • Cubic (Bicubic): A good balance between speed and quality.
   • Linear (Bilinear): Faster, but may produce slightly lower quality results.
   • NoHalo: Useful for upscaling images containing sharp edges and fine lines.
   • LoHalo: Simmilar to NoHalo but less aggressive.

   For most general resizing, "Lanczos (Sinc)" or "Cubic (Bicubic)" are suitable choices.

5. Scale: Once you've entered your desired settings, click the "Scale" button. GIMP will then resize your image.

Example:

Let's say you have an image that's 1200 pixels wide and 800 pixels high, and you want to reduce its width to 600 pixels while maintaining the aspect ratio.

1. Open the image in GIMP.
2. Go to Image > Scale Image.
3. In the "Scale Image" dialog box, ensure the chain icon is linked.
4. Enter "600" in the "Width" field. The "Height" field will automatically adjust to 400 pixels.
5. Select "Lanczos (Sinc)" as the Interpolation method.
6. Click "Scale".

Your image is now 600 pixels wide and 400 pixels high. Remember to save the resized image. Go to File > Export As and choose your desired file format and settings.