PSA Monochrome Definition
An image is considered to be Monochrome only if it gives the impression of having no colour (i.e. contains only shades of grey which can include pure black and pure white) OR it gives the impression of being a greyscale image that has been toned in one colour across the entire image (for example by sepia, red, gold, etc). A greyscale or multi-coloured image modified or giving the impression of having been modified by partial toning, multi-toning or by the inclusion of spot colouring does not meet the definition of monochrome and shall be classified as a Colour Work.

FIAP Monochrome Definition
A black and white work fitting from the very dark grey (black) to the very clear grey (white) is a monochrome work with the various shades of grey. A black and white work toned entirely in a single colour will remain a monochrome work able to stand in the black and white category; such a work can be reproduced in black and white in the catalogue of a salon under FIAP Patronage. On the other hand, a black and white work modified by a partial toning or by the addition of one colour becomes a colour work (polychrome) to stand in the colour category; such a work requires colour reproduction in the catalogue of a salon under FIAP Patronage.

FIAP and PSA Nature Definition
This new common definition came into effect from 1 January, 2015.

Nature photography is restricted to the use of the photographic process to depict all branches of natural history, except anthropology and archaeology, in such a fashion that a well-informed person will be able to identify the subject material and certify its honest presentation.

The story telling value of a photograph must be weighed more than the pictorial quality while maintaining high technical quality.
Human elements shall not be present, except where those human elements are integral parts of the nature story such as nature subjects, like barn owls or storks, adapted to an environment modified by humans, or where those human elements are in situations depicting natural forces, like hurricanes or tidal waves.
Scientific bands, scientific tags or radio collars on wild animals are permissible. Photographs of human created hybrid plants, cultivated plants, feral animals, domestic animals, or mounted specimens are ineligible, as is any form of manipulation that alters the truth of the photographic statement.
No techniques that add, relocate, replace, or remove pictorial elements except by cropping are permitted.
Techniques that enhance the presentation of the photograph without changing the nature story or the pictorial content, or without altering the content of the original scene, are permitted including HDR, focus stacking and dodging/burning.
Techniques that remove elements added by the camera, such as dust spots, digital noise, and film scratches, are allowed.
Stitched images are not permitted.
All images must appear natural.
Colour images can be converted to greyscale monochrome.
Infrared images, either direct captures or derivations, are not allowed.
Images entered in Nature sections meeting the Nature Photography Definition above can have landscapes, geologic formations, weather phenomena, and extant organisms as the primary subject matter. This includes images taken with the subjects in controlled conditions, such as zoos, game farms, botanical gardens, aquariums and any enclosure where the subjects are totally dependent on man for food.

SIE Landscape Definition
This Class encompasses Landscapes, Seascapes, Waterscapes, Skyscapes and/or Cityscapes. Any scenic view where the main subject matter is the view captured and depicted. People may be included in the scene as long as they are ancillary and or supportive of the main subject.

Landscape images entered in this class may be colour or monochrome.

The integrity of the subject must be maintained and the making of physical changes to the landscape is not permitted. You may not, for example, remove fences, move trees or place in the sky from another image. Digital adjustments including dodging and burning, changes to tone & contrast and cropping are allowed, as are High Dynamic Range imaging techniques, stitched panoramas and focus stacking.

Authentic Wildlife
Images entered in Wildlife sections meeting the Nature Photographic Definition above are further defined as one of more extant zoological or botanical organisms free and unrestrained in a natural or adopted habitat.

Landscapes, geologic formations, photographs of zoo or game farm animals, or of any extant zoological or botanical Species species taken under controlled conditions are not eligible in Wildlife sections.
Wildlife is not limited to mammals, birds and insects. Marine subjects and botanical subjects (including fungi and algae) taken in the wild are suitable wildlife subjects, as are carcasses of extant species.
To be eligible for a PSA wildlife medal, the entrant must certify that the photograph complies with both the general nature and authentic wildlife definitions by ticking the “W” box provided.