Here’s what matters:

Anything in a photograph that does not fall into the category “tones and colors” cannot be changed — except in a few select ways — or the photo will be disqualified from the Trust Test.

Phrased another way, as per P2, the shape, size, position, blurriness, and presence of forms and shapes cannot be changed in a TTG photograph except as specified in the Allowable Changes list.

Here’s the advanced explanation:

1. Every aspect of every depiction in a photograph falls into either the “light”-related or non-“light”-related category. (Most depictions of things in photographs contain both aspects.)

2. Non-“light”-related aspects are everything other than the “tones and colors” in a photograph.

3. When it comes to non-“light”-related aspects, cameras always record exactly “what the camera lens saw” (unlike “light”-related aspects, for which cameras do not always record exactly “what the camera lens saw”)

4. Unlike “light”-related aspects — some of which always change when a photograph is converted to a new medium — non-“light”-related aspects never change on their own. Someone or something has to intervene to change them. More on #3 and #4

5. Because of #3 and #4, viewers are understandably wary of any changes to non-“light”-related aspects. More on #5

6. Everything in a photograph that has a shape has multiple non-“light”-related aspects — including its shape, size, position, blurriness, and its presence — none of which can be changed in a TTG photograph except as allowed for in the Allowable Changes list linked in P2.

Note that it isn’t just three-dimensional objects (e.g., cars, buildings, trees, people) that “have a shape” when depicted in photographs:

Shadows, rainbows, reflections, catchlights in eyes, stains, patterns in clothing (e.g., stripes, dots, plaids), marks on skin (e.g., tattoos, scars, birthmarks, moles), a stain, ripples on water, a bolt of lightning, a shaft of light, flames, printed words, images on a computer screen or TV, graffiti, a scuff mark, skid marks on pavement, a logo, the words on a sign, motion blur, the markings on an animal, contrails in the sky—

— all of these “forms and shapes” — and more — are subject to the limits enumerated in P2.