Wikipedia:What is a featured picture?/Examples of technical problems

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There is no agreed definition of what constitutes a featured picture. However, Wikipedia featured picture candidates should not display any of the following technical flaws, unless there are strong mitigating reasons, such as historical significance or unique subject matter: see the featured picture criteria page for guidelines, and the WP:WIAFP/example subject matter gallery for examples of notable exceptions.

Contents

[edit] Exposure, contrast and lighting problems

Poor lighting and under-exposure with low contrast
Over-exposed, undesirable motion blur, main subject partially obscured and out of focus
Blown-out highlights due to high-contrast lighting.
Top: original image.
Bottom: blown-out areas marked red
Example of excessive image noise (grain) due to a high sensitivity (ISO) necessitated by poor lighting.

[edit] JPEG compression, colour fringing and post-processing artifacts

Loss of detail due to JPEG artifacts
Large number of (block-shaped) JPEG artifacts
JPEG artifacts closeup
Example of excessively post-processed image.
Left: original image.
Right: over-sharpened, with both excessive colour saturation and contrast.

At thumbnail size, image appears clear, at the size on the image page small artifacts can be seen, but at 100% (actual size) the image is heavily artifacted with JPG compression blocks over the entire photograph.
Purple fringing, a form of chromatic aberration. See here for a closeup.

[edit] Focus, content and composition errors

Main subject not entirely in focus (depth of field too shallow)
Poor composition: subject partially obscured
Even a small tilt is noticeable. Editing the image may fix the issue.

Unencyclopedic composition

[edit] Copyright status

The Wikipedia logo is copyrighted to the Wikimedia foundation, and is not released under a free licence. It's also about the only non-free image that policy allows us to show here

Be on the lookout for derivative works of 3D objects such as statues and scuptures. This one's OK - the author died about 200 years ago. Check Commons:Freedom of panorama to see whether such derivative works are permitted to be freely licensed.