MANIPULATION:
Manipulation is strictly prohibited in the Nature Birds, Nature No Birds, Photo Travel, Street Photography, Sport, and Photojournalism categories, as well as in any categories defined accordingly (always check, especially for Salons as there are often different rules for those categories).

Processing or editing must be limited to making the image look as close to the original scene as possible, apart from conversion to grayscale monochrome, which is permitted. Over processed images will be disqualified.

Editing techniques that are NOT allowed when the rule says "no manipulation":
• Removing, adding to, moving or changing any part of an image, except for cropping and straightening.
• In Nature Birds and Nature No Birds, NO vignette may be added.
• Blurring parts of the image during processing to hide elements in the original scene.
• Darkening parts of the image during processing to hide elements in the original scene.
• All conversions other than to complete grayscale monochrome.
• Conversion of parts of an image to monochrome, or partial toning, desaturation or oversaturation of color.

Allowed editing techniques under "no manipulation", i.e. Limited Editing
• Cropping, straightening and perspective correction.
• Flipping an image horizontal or vertical.
• Removal or correction of elements added by the camera or lens, such as dust spots, noise, chromatic aberration and lens distortion.
• Global and selective adjustments such as brightness, hue, saturation and contrast to restore the appearance of the original scene.
• A very subtle vignette is allowed except in Nature Birds and Nature No Birds.
• Complete conversion of color images to grayscale monochrome.
• Blending of multiple images of the same subject and combining them in camera or with software (exposure blending/HDR or focus stacking). In the case of Nature, exposure blending/HDR and focus stacking will not be considered as manipulation and may be used provided that the end result is a faithful representation of the original scene. Exposure blending/HDR and Focus stacking are NOT allowed in Photojournalism.
• Image stitching - combining multiple images with overlapping fields of view that are taken consecutively (panoramas).

In Open categories and those where manipulation is permitted, there are no limits on how authors may choose to post-process an image.

NATURE IN GENERAL

Nature photography records all branches of natural history except anthropology and archaeology. This includes all aspects of the physical world, both overwater and underwater. Nature images must convey the truth of the scene. A well-informed person should be able to identify the subject of the image and be satisfied that it has been presented honestly and that no unethical practices have been used to control the subject or capture the image. Images that directly or indirectly show any human activity threatening a living organism’s life or welfare are not allowed.

The most important part of a Nature image is the nature story it tells. High technical standards are expected, and the image must look natural.
• Objects created by humans, and evidence of human activity, are allowed in Nature images only when they are a necessary part of the Nature story.
• Photographs of human-created hybrid plants, cultivated plants, feral animals, domesticated animals, human-created hybrid animals, and mounted or preserved zoological specimens are not allowed.
• Photographs made where the scene is natural and the animal is unharmed in a carefully managed environment, such as Zoo, rescue centers, and ethically managed natural environment farms are permitted.
• Attracting or controlling subjects using food or sound for the purpose of photographing them is not allowed. Maintained situations such as provided supplemental food due to hardship caused by weather conditions or other conditions beyond the animals’ control, where photography is incidental to the feeding of the animal does not fall under this provision.
• Controlling live subjects by chilling, anesthetic, or any other method of restricting natural movement for a photograph is not allowed.
• Human-made elements shall be permitted under the following circumstances:
(a) When they are an integral part of the nature story, such as a songbird singing atop a fence post a man-made object used as nest material, or a weather phenomenon destroying a man-made structure.
(b) When they are a small but unavoidable part of the scene, such as an unobtrusive footprint or track in the background.
(c) Scientific tags, collars, and bands are specifically allowed.
• When photographing at a zoo, sanctuary, or rehabilitation center, it would be construed that the photographer ensured that it is properly accredited and conforms to best practices.