How to De-Pixelate Photos in GIMPby Jason ArtmanUpdated January 11, 2019
A pixelated photo has a jagged, block like appearance resulting from enlarging a small picture to a much larger size. A photo can also appear pixelated because of a high level of JPEG compression or because of noise added by a poor-quality digital camera image sensor. Although the free image editing program GIMP has no tool for automatically fixing pixelated images, it has a variety of tools that apply a gentle blur to a photo to mask different types of pixelation.
Launch GIMP using the Start menu or desktop shortcut. Click "File" at the top of the main window, then click "Open." Double-click the photo that you want to remove pixelation from.
Click "Blur" on "Filters" Menu
Click the "Filters" menu at the top of the screen, then click "Blur." Click "Blur" again on the expanded menu. This softens the entire image slightly, making the pixelation less evident.
Create Selection Box
Click and drag the mouse pointer from the upper-left corner of the most pixelated area of the photo to the lower-right. This creates a selection box. Press the "Ctrl" and "C" keys simultaneously to copy the selection to the Windows clipboard. Click the "Edit" menu at the top of the screen, then click "Paste As" and "New Image." This creates a new image from your selection.
Click the "Filters" menu, then click "Blur" and "Selective Gaussian Blur." Adjust the "Blur Radius" and "Max Delta" fields to modify the amount of blur applied. The Selective Gaussian Blur tool can blur a photo much more than the Blur tool, but it works well for repairing badly pixelated images.
Click "Enhance" and "Despeckle"
Click the "Filters" menu at the top of the screen, and click "Enhance" and "Despeckle." Adjust the "Radius" slider to change the amount of blur applied to the image. Generally, the "Black Level" and "White Level" sliders should be left alone for best results. Click "OK" to apply the filter. The Despeckle filter in GIMP produces best results with a photo that appears pixelated because of artifacts created by a digital camera's image sensor.