Feature: #93981 - Specify default image conversion processing 

Description 

ImageProcessing in TYPO3 can now configure default and specific formats to use when images are rendered / converted in the frontend, like in Fluid:

<f:image src="{asset.path}" width="200" />
<f:image src="fileadmin/someFile.jpg" width="200" />
<f:image image="{someExtbaseObject.someAsset}" width="200" />

Depending on the TYPO3 version, processed images were rendered with .png (or earlier, .gif/.png) file extensions, as long as the fileExtension parameter with a fixed output format was not specified.

This default solution had two major drawbacks:

1. The default file format was hardcoded and not configurable.
2. Utilizing new file formats (like webp and avif) required code changes.

This has now been changed with the new configuration option $GLOBALS['TYPO3_CONF_VARS']['GFX']['imageFileConversionFormats'] .

This variable is set to the array of ['jpg' => 'jpg', 'jpeg' => 'jpeg', 'gif' => 'gif', 'png' => 'png', 'svg' => 'svg', 'default' => 'png'] by default, which means:

• When resizing/cropping an image with a file extension jpg, jpeg, gif, png, svg (and not setting a specific fileExtension target format), all these images will retain their respective file formats.
• Otherwise, the file format png is used.

Related to this, the following configuration options still apply:

• $GLOBALS['TYPO3_CONF_VARS']['GFX']['imagefile_ext']

  current default: gif,jpg,jpeg,tif,tiff,bmp,pcx,tga,png,pdf,ai,svg,webp,avif

• $GLOBALS['TYPO3_CONF_VARS']['SYS']['textfile_ext']

  current default: txt,ts,typoscript,html,htm,css,tmpl,js,sql,xml,csv,xlf,yaml,yml

• $GLOBALS['TYPO3_CONF_VARS']['SYS']['mediafile_ext']

  current default: gif,jpg,jpeg,bmp,png,webp,pdf,svg,ai,mp3,wav,mp4,ogg,flac,opus,webm,youtube, vimeo,avif

These are still used to indicate on a per-installation level, which kind of files can be uploaded/uses as image files.

If in the future a new file format like heic can be used on all platforms, and the used graphic engine (like GraphicsMagick or ImageMagick) supports writing these formats, system maintainers can enable TYPO3 to utilize this format in TYPO3 by adding that file extension to the list of imagefile_ext. This would recognize that new image format, and by default on any image crop/conversion operation, would convert that to the default target format (png for now).

If additionally that format should be usable by image processing operations with that output format, this can be achieved by adding heic => heic to the option $GLOBALS['TYPO3_CONF_VARS']['GFX']['imageFileConversionFormats'] . Without adding the file extension to that list, heic images could be selected as images, but default file processing would always enforce png.

If the image format heic should be used for ALL default image processing (even cropping or resizing jpg, creating pdf thumbnails and any other images), this can be achieved by setting the special key default => heic (instead of default => png) and dropping all other image formats from the array.

The option can not yet be configured in the Admin Tools > Settings > Configure options ... backend module due to its array syntax. The ability to set the option in the GUI may be planned for a follow-up feature. This means, for now, it can only be set by editing the settings.php file manually.

The array notation allows to not only set the default => {fileExtension} key and file extensions, but also to set a processed (thumbnail) target file extension for each original file extension individually. This can be achieved by using the notation {originalFileExtension} => {processingFileExtension}.

For example this configuration:

$GLOBALS['TYPO3_CONF_VARS']['GFX']['imageFileConversionFormats'] = [
    'jpg' => 'jpg',
    'svg' => 'svg',
    'ai' => 'png',
    'heic' => 'webp',
    'default' => 'avif',
];

would render images like this:

<f:image src="somefile.jpg" width="80">
  -> would render a 80px thumbnail from
     "somefile.jpg" to "somefile.jpg" due to "jpg => jpg"

<f:image src="somefile.gif" width="80">
  -> would render a 80px thumbnail
     from "somefile.gif" to "somefile.avif" due to "default => avif"
     and no distinct format listing

<f:image src="somefile.png" width="80">
  -> would render a 80px thumbnail
     from "somefile.png" to "somefile.avif" due to "default => avif"
     and no distinct format listing

<f:image src="somefile.svg" width="80">
  -> would render the original SVG at 80px width
     from "somefile.svg" to "somefile.svg" due to "svg => svg"

<f:image src="somefile.pdf" width="80">
  -> would render a PDF thumbnail at 80px width
     from "somefile.pdf" to "somefile.avif" due to "default => avif"

<f:image src="somefile.heic" width="80">
  -> would render a 80px thumbnail
     from "somefile.heic" to "somefile.webp" due to "heic => webp"

Impact 

TYPO3 is now more future-proof for using upcoming file formats, and allows to utilize modern file formats by configuration.

Also, projects can now receive specific configuration on how to convert each file format as a processed image as well as the default format.