什么是年金

百度 当今社会，基础数学的各个分支在密码学、经济学、电子商务、建筑、医学成像、疫苗研制等重要领域均有应用。

Whenever images are included in Wikipedia, it makes a big difference if they look good. When they do, an article appears more professional and is more pleasant to read. When they look amateurish, the article looks amateurish.

Tools

Images can often be improved – or even transformed – by using graphics software such as Photoshop or the free GIMP and Paint.NET applications. Many other programs also have photo-enhancing tools, including facilities for semi-automatic image enhancement, so that you need only click a button, or choose a thumbnail, to have a positive effect on image quality.

Always upload modified images under a new filename, and link between them and the original.

Checklist

Here are some things that should be kept in mind before uploading images:

• Check composition Cropping an image to remove irrelevant parts of it can make the subject more prominent and improve its visual balance. If the centre of a scene isn't vertical or the horizon isn't horizontal, it might also be an idea to rotate it before cropping.
• Check color Make sure the colours look natural. If the photo looks too "cold" or too "warm", it can often be easily corrected using a color balance adjustment.
• Check brightness If the image seems dark or the colors are dull, correct the brightness and contrast using a "levels" or "curves" dialogue.
• Check graininess If there is excessive image noise (possible with some film scans, and very likely with digital shots taken in low light) try using a noise removal program such as Noise Ninja (commercial), Neat Image (commercial) or G'MIC (open source).
• Check size Although it may only need to appear small in the encyclopedia article, bear in mind that people might need an image in high resolution. The default minimum size for consideration as a Commons featured picture is 2 megapixels, for example. The current maximum file size you can upload is 100MB.
  • If, when viewed at 100% (actual pixels), an image appears slightly blurred and/or there are visible JPEG compression artifacts, it could benefit from downsampling. Images from modern digital cameras which produce very large (6MP or 10MP) files can look much better when slightly reduced in size.
• Check format Always save photographs as high quality JPEGs. If the image is made on the computer and is not a photograph, painting, or scan, it probably shouldn't be in JPEG format at all – see Preparing images for upload: Do not save diagrams as JPEG.

Other improvements

It's also possible to make seemingly impossible corrections, such as correcting "leaning" buildings or removing unwanted obstructions. Perspective distortion can be fixed afterwards, or a tourist standing in front of an otherwise clearly-photographed building can be cloned out. This can be difficult to do well, even for experienced image editors. If you clearly see that the image needs improvement but feel that any of the above improvements are best left to an expert, upload it anyway and then ask for assistance on Wikipedia:Graphic Lab, the help desk, on this article talk page, or elsewhere. You'll find a ready supply of willing editors capable of first rate improvements – all you have to do is ask!

Uploading

English Wikipedia allows images to be hosted here which are public domain in the United States, but not their source country. With the exception of these (which are forbidden there), remember to always upload images to Wikimedia Commons, the repository for all metawiki images, as the image is then made available to projects in other languages. The wikilinks to images are exactly the same as those uploaded directly to en:Wikipedia. If you make any of the above improvements to an image, upload it under a new filename, and link between it and the original. You might also want to submit your images to Picture peer review, where it will be critically assessed by experienced contributors and – who knows? – might be considered a suitable featured picture candidate!

See also

• Image editing: overview of editing methods for raster-based images
• Image use policy: general information on using images on Wikipedia
• Images for cleanup: what to do if you see an image in need of improvement
• Preparing images for upload: choosing the right file format
• Picture tutorial: how to add your pictures to articles
• Graphs on Wikipedia: how to create graphs for Wikipedia articles
• Vector graphics: overview of editing methods for vector-based images
• Wikipedia:SVG Help: help with vector image upload problems
• Wikipedia:Graphics Lab: help with almost any image question
• Wikipedia:Graphics Lab/Images to improve: assistance with editing or improving particular images