Image file objects are classed

Utility methods in image.inc were removed in favour of a classed image object.
A new service 'image.factory' was added for easy instantiation of image objects using the active image toolkit.

Image loading and saving

What	Drupal 7	Drupal 8
Load an image from a file:	`$image = image_load($file->getFileUri());`	`$image = Drupal::service('image.factory')->get($file->getFileUri());`
Save image at its original file location:	`image_save($image);`	`$image->save();`

Image information

What	Drupal 7	Drupal 8
Get information about the image:	`image_get_info($image);`	removed
Check if an image is valid (i.e. can be manipulated/saved to file storage):	n/a	`$is_valid = $image->isValid();`
Get image width:	`$info = image_get_info($image); $width = $info['width'];`	`$width = $image->getWidth();`
Get image height:	`$info = image_get_info($image); $height = $info['height'];`	`$height = $image->getHeight();`
Get the MIME type of the image file:	`$info = image_get_info($image); $mime_type = $info['mime_type'];`	`$mime_type = $image->getMimeType();`
Get image file size:	`$info = image_get_info($image); $filesize = $info['filesize'];`	`$filesize = $image->getFileSize();`
Get the URI of the image file:	N/A	`$source = $image->getSource();`
Get a list of image file extensions supported by the current toolkit:	N/A	`$image_factory = \Drupal::service('image.factory'); $supported_extensions = $image_factory->getSupportedExtensions();`

Image manipulation

What	Drupal 7	Drupal 8
Create a new image:	n/a	`$image->createNew($width, $height, 'jpeg');`
Scale and crop image:	`image_scale_and_crop($image, $width, $height);`	`$image->scaleAndCrop($width, $height);`
Scale image:	`image_scale($image, $width, $height);`	`$image->scale($width, $height);`
Resize image:	`image_resize($image, $width, $height);`	`$image->resize($width, $height);`
Rotate image:	`image_rotate($image, $degrees);`	`$image->rotate($degrees);`
Crop image:	`image_crop($image, $x, $y, $width, $height);`	`$image->crop($x, $y, $width, $height);`
Desaturate image (convert to grayscale):	`image_desaturate($image);`	`$image->desaturate();`
Convert image to a different format:	n/a	`$image->convert('jpeg');`
Apply a custom toolkit operation to the image:	`image_toolkit_invoke('my_op', $image, array('p1' => $parm1, 'p2' => $parm2));`	`$image->apply('my_op', array('p1' => $parm1, 'p2' => $parm2));`

Accessing an Image's toolkit

What	Drupal 7	Drupal 8
Access image toolkit instance:	N/A	`$toolkit = $image->getToolkit();`
Get the ID of the image toolkit:	N/A	`$toolkit_id = $image->getToolkitId();`
GD Toolkit - get the standard file extension of the image, based on its internal type (for GD, jpeg/png/gif):	`$info = image_get_info($image); $extension = $info['extension'];`	`$extension = image_type_to_extension($image->getToolkit()->getType(), FALSE);`