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Troubleshooting NextGEN Gallery Image Resizing and Artifact Issues

23 threads Sep 16, 2025

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Many NextGEN Gallery users encounter problems where images appear distorted, pixelated, or have strange color artifacts after the plugin resizes them to create thumbnails or other sizes. This guide will explain why this happens and provide the most common solutions to fix it.

Why Do Resizing Artifacts Happen?

Based on community reports and investigations by the 'Photo Gallery, Sliders, Proofing and Themes – NextGEN Gallery' team, these issues are often linked to the ImageMagick (Imagick) image processing library on the server. Incompatibilities between certain Imagick library versions (particularly 3.5 and above) and the plugin can cause images to be processed incorrectly, leading to a reduced color palette, distortion, or artifacts.

Common Solutions

1. Disable the Imagick Module

The most frequently suggested workaround is to disable NextGEN Gallery's use of the Imagick module. This forces the plugin to use an alternative image processing library (likely GD).

  1. Access your website's files, typically via FTP or your hosting provider's file manager.
  2. Locate and edit the wp-config.php file in the root directory of your WordPress installation.
  3. Add the following line of code above the line that says /* That's all, stop editing! Happy publishing. */: 
    define('NGG_DISABLE_IMAGICK', true);
  4. Save the file and upload it back to your server if necessary.

Important: After applying this fix, you must regenerate your images for the changes to take effect.

2. Regenerate Image Thumbnails

Whether you change the Imagick setting or not, corrupted images need to be regenerated. You can do this in two ways:

  • Per Gallery: Navigate to Galleries -> Manage Galleries. Click on a specific gallery, then select the images and use the "Create new thumbnails" option.
  • Global Cache Clear: Go to NextGEN Gallery -> Other Options -> Miscellaneous. Click the "Clear image cache" button. This will cause all images to be regenerated the next time they are viewed, which may temporarily slow down your site.

3. Check Thumbnail Crop Settings

If images are distorted (stretched or squashed) but not pixelated, the issue may be with the thumbnail cropping settings. To ensure consistent sizing:

  1. Go to Gallery -> Gallery Settings.
  2. Modify your default settings by enabling "Override thumbnail settings".
  3. Choose a specific size for your thumbnails and set "Thumbnail crop" to "Yes".
  4. Save changes and clear your image cache (as described above) to regenerate all thumbnails with the new settings.

What If These Solutions Don't Work?

If the problem persists, it can be helpful to provide specific details when seeking help from the community. The 'Photo Gallery, Sliders, Proofing and Themes – NextGEN Gallery' team has requested that users experiencing Imagick-related issues report their Imagick library version. You can find this information by going to Tools > Site Health > Info in your WordPress dashboard, clicking "Copy site info to clipboard", and then pasting that information into a text file to find the Imagick version.

By following these steps, most users can resolve image quality and display issues related to NextGEN Gallery's image processing.

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