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Wikipedia:How to improve image quality

From Wikipedia, the free encyclopedia
This help page is ahow-to guide.
It explains concepts or processes used by the Wikipedia community. It is not one ofWikipedia's policies or guidelines, and may reflect varying levels ofconsensus.

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

Tools

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Images can often be improved – or even transformed – by usinggraphics software such asPhotoshop or the freeGIMP andPaint.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

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

  • Check compositionCropping an image to remove irrelevant parts of it can make the subject more prominent and improve itsvisual balance. If the centre of a scene isn't vertical or the horizon isn't horizontal, it might also be an idea torotate 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 acolor balance adjustment.
  • Check brightness If the image seems dark or the colors are dull, correct thebrightness and contrast using a "levels" or "curves" dialogue.
  • Check graininess If there isexcessiveimage noise (possible with some film scans, and very likely with digital shots taken in low light) try using a noise removal program such asNoise Ninja (commercial),Neat Image (commercial) orG'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 inhigh resolution. The default minimum size for consideration as aCommons 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 visibleJPEGcompression artifacts, it could benefit fromdownsampling. 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 – seePreparing images for upload: Do not save diagrams as JPEG.

Other improvements

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It's also possible to make seemingly impossible corrections, such as correcting "leaning" buildings or removing unwanted obstructions.Perspective distortion can befixed afterwards, or a tourist standing in front of an otherwise clearly-photographed building can becloned out.This can be difficult to do well, even for experienced image editors. If you clearly see that the image needs improvement but feel thatany of the above improvements are best left to an expert, upload it anyway and then ask for assistance onWikipedia: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

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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 toPicture peer review, where it will be critically assessed by experienced contributors and – who knows? – might be considered a suitablefeatured picture candidate!

See also

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