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Manual Chapter: Accelerating Images with Image Optimization
Manual Chapter
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Overview: Accelerating images with image optimization

You can configure image optimization in a BIG-IP policy to reduce the size of image files, for example, by removing unnecessary metadata, by changing the format, or by increasing compression, and, consequently, accelerate the transfer of image objects across a network.

When an image object is matched to a policy node, it is modified in accordance with the acceleration rules of the policy. Configurable acceleration rules for an image object include several parameters.

Note: Image optimization only benefits raster images. Vector images, such as SVG files, benefit little from image optimization, but can benefit from file compression. You can use file compression to improve the performance of vector images.

Task summary for optimizing images

Perform these tasks to reduce the file size of images by using image optimization.

Task summary

Accelerating images by optimization

You can reduce the size of image files by removing unnecessary metadata, changing the file format, or using compression, and, consequently, accelerate the transfer of image objects across a network.
Note: F5Networks recommends examination of converted file sizes for different file formats to optimize performance with a reduced file size.
  1. On the Main tab, click Acceleration > Web Application > Policies. The Policies screen displays a list of existing acceleration policies.
  2. Click the name of a user-defined acceleration policy.
  3. Click a node in the Policy Tree.
  4. From the Matching Rules menu, choose Acceleration Rules.
  5. On the menu bar, click Assembly. The screen refreshes to show assembly options.
  6. From the Content Assembly Options list, select Advanced.
  7. Scroll to the Image Optimization Settings area of the screen, select an image optimization option, and configure the displayed settings, as applicable.
    Note: The configuration steps change depending on the setting you select.

Image optimization option Description Configuration steps
No Optimization Default for all policies except Generic Complete. No image optimization is performed. None.
to JPEG Converts the image associated with the policy node into a JPEG, in accordance with specified settings.
  • For the JPEG Quality setting, select one of the options.
    • Absolute. Specifies a quality level for compression
    • Relative. Specifies a percentage of compression relative to the original JPEG file.
  • In the JPEG Quality Factor field, type a quality factor number for the selected JPEG Quality option.
  • Select the Strip EXIF keeps copyright check box to preserve copyright metadata when the BIG-IPsystem strips other metadata from the EXIF header.
  • For the Strip/Safe-strip JPEG EXIF Header setting, select one of the options.
    • Don't Strip EXIF. The EXIF header is not changed.
    • Always Strip EXIF. The EXIF header is always removed from the JPEG file.
    • Strip EXIF if safe. The EXIF header is always removed, unless the header includes a color profile.
    • Apply color profile, then strip EXIF. After the color profile is applied, the EXIF header is always removed. This option converts the image to the default color profile, so that the EXIF header can be safely removed.
  • For the JPEG Sampling Factor setting, select one of the options.
    • Preserve. The sampling factor matches the brightness and color values of the original file.
    • 1x1. Provides the same sampling factor for the brightness and color values.
    • 2x1. Averages color values for horizontal pixels.
    • 1x2. Averages color values for vertical pixels.
    • 2x2. Averages color values for both vertical and horizontal pixels.
  • Select the Use Progressive Encoding check box to enable browsers to quickly render a low-quality version of the entire image.
  • Select the Optimize For Client check box to convert images associated with the policy node into a WebP or a JPEG-XR image format.
  • In the WebP Quality Factor field, type a quality factor number for the selected Optimize for Client option.
  • In the JPEG-XR Factor field, type a quality factor number for the selected Optimize for Client option.
to GIF Converts the image associated with the policy node into a GIF.
  • Select the Optimize For Client check box to convert images associated with the policy node into a WebP or a JPEG-XR image format.
  • In the WebP Quality Factor field, type a quality factor number for the selected Optimize for Client option.
  • In the JPEG-XR Factor field, type a quality factor number for the selected Optimize for Client option.
to PNG Converts the image associated with the policy node into a PNG, in accordance with specified settings.
  • Select the Reduce to 256 Colors check box to reduce the file size with minimal degradation in the quality of the image.
  • Select the Optimize For Client check box to convert images associated with the policy node into a WebP or JPEG-XR image format.
  • In the WebP Quality Factor field, type a quality factor number for the selected Optimize for Client option.
  • In the JPEG-XR Factor field, type a quality factor number for the selected Optimize for Client option.
to TIFF Converts the image associated with the policy node into a TIFF.
  • Select the Optimize For Client check box to convert images associated with the policy node into a WebP or JPEG-XR image format.
  • In the WebP Quality Factor field, type a quality factor number for the selected Optimize for Client option.
  • In the JPEG-XR Factor field, type a quality factor number for the selected Optimize for Client option.

  1. Click Save.
  2. Publish the acceleration policy.
    1. Click Publish.
    2. In the Comment field, type a description.
    3. Click Publish Now.
The size of the image files is reduced to accelerate the transfer of image objects across a network.

Disabling image optimization for a node

You must have already enabled image optimization for image objects on a node.
You can, if necessary, disable image optimization for a specific node, thus requiring the unoptimized, original image files to download.
  1. On the Main tab, click Acceleration > Web Application > Policies. The Policies screen displays a list of existing acceleration policies.
  2. Click the name of a user-defined acceleration policy.
  3. Click a node in the Policy Tree.
  4. From the Matching Rules menu, choose Acceleration Rules.
  5. On the menu bar, click Assembly. The screen refreshes to show assembly options.
  6. From the Content Assembly Options list, select Advanced.
  7. Scroll to the Image Optimization Settings area of the screen, and for the Optimize image setting, select the No Optimization option.
  8. Click Save.
  9. Publish the acceleration policy.
    1. Click Publish.
    2. In the Comment field, type a description.
    3. Click Publish Now.
This disables image optimization for the node.
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