1) Add encyclopedic value (EV) to an article. One of the ways EV is judged is by the amount of time an image is kept in an article. To be eligible, an image must be in an article for at least one month prior to nomination. This shows that other editors concur that the image is well used in an article, implying that the image has at least some EV. Also, images must be well used in an article (or, preferably, multiple articles); images used solely in galleries will not be promoted because they do not offer much EV. 2) Be among Wikipedia's most educational work. It leads a user to want to know more about the subject, or explains a concept or process in a simple, understandable manner. 3) Not be featured. Since FPs are already recognized for their encyclopedic value, a picture cannot be valued and featured at the same time. However, delisted FPs are eligible to be nominated for VP. 4) Be freely licensed. All valued pictures must either be in the public domain or freely licensed. No images with a "fair use" justification are accepted. Information supporting the license must therefore be provided on the image description page. (See related stories: Reviewing free images and Reviewing non-free images.) 5) Have a complete caption which explains the content of the image, identifies its subject and outlines any relevant metadata. The caption must be succinct—extended information is best placed on the image description page.
The main differences between FP and VP are the quality expectations of a given image. VP is not as strict about quality, but does expect an image to be reasonable enough for positive use in at least one article. Some quality problems, such as compression artifacts, blown highlights, crushed blacks, etc., are forgivable. However, technical problems must not compromise the accuracy and value of the image: VPs are expected to have an accurate color balance and exposure, and the subject should not be tilted, cut off, or obscured without a sufficient reason. For practical examples of acceptable and unacceptable technical problems, see the case studies below.
The VP expectation of high EV is necessary but not sufficient for promotion to FP. The valued pictures project is not a dumping ground for failed Featured picture candidates (FPC). While failed FPCs are welcome, they must still meet the VP criteria and not all failed FPCs will succeed.
The VPC process is modelled on the FPC process—an image can only be promoted if it receives four support votes and has a favourable consensus in approximately seven days.
Commons hosts a valued images program (VI), which is similar to the VP program at the English Wikipedia. The main difference is that Commons looks for potential value across all Wikimedia projects, not just the English Wikipedia. Another major difference is that at Commons VI, each image must be the most valued illustration within one or more scopes. Wikipedia VP does not use scopes; rather it just judges the general EV of a given image here on the English Wikipedia.
It is also possible to nominate sets of valued images. This is not explicitly allowed on Wikipedia—typically one can get away with nominating two closely related images, any more will likely see the nomination fail due to lack of interest or consensus. Here is an example valued image set.
For promotion, a Commons valued image candidate must have a straight majority vote in support after seven days. There is no quorum. Valued images can be demoted through a Most Valued Review, where the values of two or more images within the same scope are compared.
Contrary to FPC where images must be evaluated at full resolution, valued picture candidates are best reviewed at article (~300 pixels) and image page (~1000 pixels) size. Reviewing at full resolution is usually unnecessary as most technical problems affecting the EV show up at image page size.
Users are encouraged to join in the discussions going on at VPC. VPC is much less intimidating at first than FPC, which has a steep learning curve due to its high technical standards and resulting use of photographic jargon. It takes a significant amount of experience to contribute to FPC effectively, while any reasonably experienced content builder will have an instinctive handle on assessing an image's EV for VPC.
Any logged-in user may nominate an image that they feel meets the criteria. Since the project is still young, it is quite easy to find eligible images. Keep VPC in mind while making your rounds on Wikipedia; if you see an image that you think adds greatly to an article (and it's not already featured or valued), don't hesitate to nominate it!
Loss of detail due to compression artifacts, noise
Clear, aesthetically pleasing view of the structure on a pleasant day. High level of EV due to its use in Template:White House, which is used in more than 50 articles. High profile images typically have lots of EV. Successful nomination.