Opti PNG

The OptiPngPostProcessor is a built-in post-processor that performs a number of lossless optimizations on PNG encoded images.

To add this post-processor to the filter set created in the thumbnail usage example use:

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        # app/config/config.yml

liip_imagine:
    filter_sets:
        my_thumb:
            filters:
                thumbnail: { size: [120, 90], mode: outbound }
                background: { size: [124, 94], position: center, color: '#000' }
            post_processors:
                optipng: { strip_all: true, level: 5 }
    

This configuration enables metadata stripping, and sets a maximum optimization factor of 5 for the resulting image binary.

Note

The default executable path is /usr/bin/optipng. If installed elsewhere on your system, you must set the liip_imagine.optipng.binary parameter accordingly.

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        # app/config/config.yml

parameters:
    liip_imagine.optipng.binary: /your/custom/path/to/optipng
    

Options

level: int: Sets the image optimization level. Valid values are integers between 0 and 7.
snip: bool: When multi-images are encountered (for example, an animated image), this causes one of the images to be kept and drops the other ones. Depending on the input format, this may be either the first or the most relevant (e.g. the largest) image.
strip_all: bool (deprecated): Removes all comments, EXIF markers, and other image metadata.
level: int: Sets the image optimization factor, from 0 to 7.
strip: bool|string: When set to true, all extra image headers, such as its comments, EXIF markers, and other metadata, will be removed. Equivalently, the string value all also removes all extra metadata.
preserve_attributes: bool: Preserve file attributes (time stamps, file access rights, etc.) where applicable/possible.
interlace_type: int: Sets the interlace type used for the output file. When set to 0, the output image will be non-interlaced. When set to 1, the output image will be interlaced using the Adam7 method. When not set, the output will have the same interlace type as the original input.
no_bit_depth_reductions: bool: Disables any bit depth reduction optimizations.
no_color_type_reductions: bool: Disables any color type reduction optimizations.
no_palette_reductions: bool: Disables any color palette reduction optimizations.
no_reductions: bool: Disables any lossless reduction optimizations, enabling no_bit_depth_reductions, no_color_type_reductions, and no_palette_reductions.

Parameters

liip_imagine.optipng.stripAll: bool: Removes all comments, EXIF markers, and other metadata from the image binary.
liip_imagine.optipng.level: int: Sets the image optimization factor. Default is 7.
liip_imagine.optipng.binary: string: Sets the location of the optipng executable. Default is /usr/bin/optipng.
liip_imagine.optipng.tempDir: string: Sets the directory to store temporary files.

Tip

The value of liip_imagine.optipng.tempDir can be set to an in-memory mount point on supported operating systems, such as /run/shm on Linux. This will decrease disk load and may increase performance.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.

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