GIMP Sharpening Tutorial

The GNU Image Manipulation Program (GIMP) is a free graphics software program that can be used for creating or editing image files, including digital photos. GIMP includes three useful tools for sharpening. The Sharpening Filter and the Unsharpen Mask can be used to sharpen an entire image. The Sharpen Tool is used for sharpening portions of an image, such as a blurry detail in the background or foreground of a photo. When using any of these tools, it is important to use a light touch at first. Over-sharpening can cause a spotty or grainy image.

Instructions

Sharpen Filter

1. Open a photo in need of sharpening from the "File" menu in GIMP.

2. Click the "Filters" menu and select "Enhance." Click "Sharpen." The Sharpen preview window opens.

3. Move the "Sharpness" slider to increase or decrease the sharpening effect.

4. Click "OK" when you are satisfied with the changes in the preview window. The effect will be applied to the image.

Unsharpen Mask

1. Click the "Filters" menu and select "Enhance." Click "Unsharpen Mask." The Unsharpen Mask preview window opens.

2. Move the "Radius" slider to increase the size selected around the edges in the image. This is measured in pixels. Try moving the slider by only a pixel or two at a time.

3. Move the "Amount" slider to increase or decrease the amount of sharpening that occurs.

4. Move the "Threshold" slider to increase or decrease the amount of noise or spotty pixels that occurs when sharpening. In most cases, a low level is best.

5. Click "OK" when you are satisfied with the results of your adjustments.

Sharpen Tool

1. Click the "Blur/Sharpen Tool" from the Toolbox. The icon looks like a drop of water.

2. Click to select the "Sharpen" option in the Convolve Type section of the Blur/Sharpen Options menu.

3. Increase or decrease the opacity of the tool by moving the "Opacity" slider. Start with a lower setting. A high-opacity setting will often create dark lines on the image.

4. Click the "Brush" icon to change the shape and size of the tool. Move the "Scale" slider to fine-tune the size of the tool selected.

5. Click "Fade Out" to fade the tool's effect as you move the mouse. Select "Apply Jitter" to randomize or scatter the effect. You can also select a "Hard Edge" for the sharpening tool, which is useful when sharpening lines.

6. Click any line in the image where you want the sharpening done. Hold down the mouse button and drag the tool across the line.

References

• The World; Really Basic Photo Editing With GIMP; Matt McIrvin
• GIMP Documentation: Blur/Sharpen