file_validate_image_resolution in includes/file.inc
If the file is an image verify that its dimensions are within the specified maximum and minimum dimensions. Non-image files will be ignored.
file_validate_is_image in includes/file.inc
Check that the file is recognized by image_get_info() as an image.
image_gd_crop in includes/image.gd.inc
Crop an image using the GD toolkit.
image_gd_resize in includes/image.gd.inc
Scale an image to the specified size using GD.
image_gd_rotate in includes/image.gd.inc
Rotate an image the given number of degrees.
image_scale in includes/image.inc
Scales an image to the given width and height while maintaining aspect ratio.
image_scale_and_crop in includes/image.inc
Scales an image to the exact width and height given. Achieves the target aspect ratio by cropping the original image equally on both sides, or equally on the top and bottom. This function is, for example, useful to create uniform sized avatars from…
user_file_download in modules/user/user.module
Implementation of hook_file_download().
user_validate_picture in modules/user/user.module