The GNU Image Manipulation Program is a graphics tool that can enhance your photo files. GIMP started as a school project by University of California students Spencer Kimball and Peter Mattis. This free software has developed into a powerful photo editor supported by contributors and volunteers. GIMP's filters can help retouch image files, including sharpen slightly blurry images. GIMP's "Unsharp Mask" filter reduces blurred effects from camera shake. This filter's "Preview" box provides a clear view of this filter's effects before you save the converted image.
Open the GIMP program. A blank image window and image menu appears.
Click the "File" menu button on the image menu. A list of simple commands appears.
Click "Open." A dialogue window opens. A list of image thumbnails and file locations appears.
Click to select the image file. Click "Open." The image appears in an image window.
Click the "Filters" image button on the image menu. A list of filter options appears, including "Enhance."
Click the "Enhance" options. A list of options appears, including "Unsharp Mask."
Click the "Unsharp Mask" filter. The "Unsharp Mask" dialogue window opens. A preview box and list of three options appear.
Select the check box for "Preview." This "Preview" box shows a small section of your image and the filter effects.
Click and drag the slider buttons for the preferred effects: "Radius," "Amount" and "Threshold." You can also type the values in the text boxes. Preview the effect in the "Preview" box before you commit to saving.
Click "OK." The image appears sharper.
The "Unsharp Mask" filter can distort colours. Avoid colour distortion by applying colour commands. Click "Colors" on the image menu. Click "Components" and "Decompose." A dialogue window opens. Select the check box for "Decompose to Layers." Click "HSV" from the text box list. Click "OK." Select one of three layers and apply the "Enhance" and "Unsharp Mask" filter. Reverse the process on that same layer: Click "Colors" from the image menu. Click "Components" and "Compose." Click "HSV" from the text box list. Click "OK." The colour image sharpens without colour distortion.