Wicipedia:Polisi defnyddio lluniau
Oddi wrth Wicipedia, y gwyddoniadur rhydd.
For multimedia in general (images, sound files, etc.) see Wikipedia:Multimedia. To upload an image, visit Arbennig:Upload.
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[golygu] Rules of thumb
Here's a quick checklist of rules for use of images. After the list, a more detailed discussion explains the reasoning behind them. See also sound help for information on uploading and listening to sound files.
- Keep copyrights in mind when uploading images.
- Use the image description page to describe an image and its copyright situation.
- Use a clear, detailed, title. Note that if any image with the same title has already been uploaded, it will be replaced with your new one.
- The ideal image width is 250 pixels, as this suits common screen resolutions. Less than 150 pixels wide is too small to see.
- The ideal image displayed inline in an article page is smaller than 35,000 bytes in size (70,000 bytes might be okay if a larger image is needed), remember that a 35,000 byte image takes about 5 seconds for a 56kbps modem to download.
- Edit the images to show just the relevant subject.
- If you create an image that contains text, please upload also a version without any text. It will help Wikipedias in other languages use them (translate them).
- Don't put photo credits in articles or on the images themselves; put them on the description page.
- Use JPEG format for photographic images, and PNG format for icons, drawings, maps, flags, and such.
- Add a good alternate text for images.
meta:Image pages discusses possible technical improvements to the wikipedia software that would simplify much of this subject in the future.
[golygu] Copyright (images)
Please note: this is not the official copyright policy - merely a reminder and additional tips
When you upload an image, make sure you own the image, or that it is in the public domain, or that the copyright holder has agreed to license it under the GFDL. Please note its copyright status on the image description page.
Under United States copyright law, all images that were published before January 1, 1923 in the United States are now in the public domain, but this does not apply to images that were created prior to 1923 and published in 1923 or later. The year 1923 has special significance and this date will not roll forward before 2019. This is particularly significant because Wikipedia pages, including the non-English language pages, are currently hosted on a server in the United States. However, the interaction of Wikipedia, the GFDL, and international law is still under discussion.
You can find a large selection of places to acquire public domain photos at the public domain image resources.
It is not the job of rank-and-file Wikipedians to police every image for possible copyright infringement. However, if you strongly suspect that an image is a copyright infringement (for example, if there is no information on copyright status on its image description page and you have seen it elsewhere under a copyright notice), then you might list it for deletion (see below).
See also:
[golygu] Editing images
To replace an image with an edited version, use the Upload file page, and make sure that your file has the same name as the one that you want to replace. Converting an image to another file format the (end of) the image name changes, hence one gets a separate image description page.
[golygu] Deleting images
- Drop a line to the person who uploaded the image, telling them of your concerns. You may be able to resolve the issue at this point.
- Remove all uses of the image from articles - make it an orphan
- Add one of these notices to the image description page
- copyvios: add the copyright infringement notice for images from Wikipedia:Possible copyright infringements to the image description page:
- otherwise: add the listed for deletion notice to the image description page.
- List the image on one of these links:
- copyvios: list the image on Wikipedia:Possible copyright infringements
- otherwise: list the image on Wikipedia:votes for deletion
- The image can then be deleted after a week in the normal way - see our deletion policy.
To actually delete an image after following the above procedure, you must be an administrator. To do so, go to the image description page and click the (del) link. Do not click the Delete this page link, as this will delete the image description page but leave the image intact. To delete the image talk page (if any), you can use the Delete this page link as usual. Deleted images cannot be undeleted! Therefore they are gone permanently unless someone happened to keep a backup.
[golygu] Image titles
Descriptive titles are also useful. A map of Africa could be called "Africa.png", but quite likely more maps of Africa will be useful in Wikipedia, so it is good to be more specific, e.g. "Africa political map.yourinitials.png". Check whether there are already maps of Africa in Wikipedia. Then decide whether your map should replace one (in each article that uses it) or be additional. In the first case give it exactly the same name, otherwise a suitable other name. Avoid special characters in filenames or excessively long filenames, though, as that might make it difficult for some users to download the files onto their machines. Note that names are case sensitive, Africa.PNG is considered different from Africa.png. For uniformity, lower case file name extensions are recommended.
You may use the same name in the case of a different image that replaces the old one, and also if you make an improved version of the same image - perhaps a scanned image that you scanned again with a better quality scanner, or you used a better way of reducing the original in scale - then upload it with the same title as the old one. This allows people to easily compare the two images, and avoids the need to delete images or change articles. However, this is not possible if the format is changed, since then at least the extension part of the name has to be changed.
Currently there is no easy way to rename an image - you have to just save it and re-upload it.
[golygu] Placement
See Wikipedia:Image markup for recommendations on the best markup to use.
[golygu] Photo montages
There are four different approaches to photo montages that different wikipedians take. Different approaches may be suitable for different subjects, or it may be possible to set a standard. The options are:
- Photos at bottom of article (Erotic art in Pompeii)
- Photos on "images of" page (eg sheep, images of sheep)
- Photos on an image description page (eg cattle)
- No photo montages allowed - only include a limited number of relevant photos
No decision on photo montages has been made yet. Please discuss pros and cons of each option on the talk page.
Note that it is not recommended to use animated GIFs to display multiple photos. The method is not suitable for printing and also is not user friendly (users can not save individual images and have to wait before being able to view images while other images cycle round)
[golygu] Format
- Drawings, icons, political maps, flags and other such images (basically those with large,simple,and continuous blocks of color) should be in PNG format.
- Photos and photo-like maps should be in JPEG format.
- Animations should be in animated GIF format.
In general, if you have a good image that is in the wrong format, convert it to the correct format before uploading. However, if you find a map, flag, etc in JPEG format, only convert it to PNG if this reduces the file size without causing artifacts. For further advice on converting JPEG to PNG, see Wikipedia:How to reduce colors for saving a JPEG as PNG.
Most of the maps on the CIA World Factbook website were coded as JPEG, but are now coded as GIF. To update these photos, download the GIF picture from the CIA factbook, recode it in PNG format, and upload it to wikipedia.
Try to avoid cropping or otherwise editing JPEGs too frequently--each edit creates more loss of quality. If you can find an original of a photograph in 16-bit or 24-bit PNG or TIFF, edit that, and save as JPEG before you upload.
Avoid images that mix photographic and iconic content. Though CSS makes it easy to use a PNG overlay on top of a JPEG image, the Wikipedia software does not allow such a technique. Thus, both parts must be in the same file, and either the quality of one part will suffer, or the file size will be unnecessarily large.
When uploading SVG images, upload both the SVG source and a rasterised version, and cross-link on the image description page. Direct SVG support is planned (see meta:SVG image support) but not yet implemented.
See also: Wikipedia:How to keep image file sizes as small as possible
[golygu] Size
There are many technical hints in this section that some people may not have the tools or expertise to deal with themselves. If, for example, you find a great image that needs to be cropped, resized, or recoded and you don't know how to do that, ask someone at Y Caffi to do it for you.
Scale and crop images to a size appropriate for the article. Keep in mind that many readers are using 800x600 displays, and so images wider than 250 pixels may overwhelm the article. Larger images also take more time to download over slow links. Likewise, images smaller than 150 pixels wide may be difficult for users of larger displays to see. An optimum size for images with text flowing around them would be 250 pixels. Images without text on the side can be wider.
In terms of image file size, please also bear in mind that not everyone has a broadband internet connection. A considerable number of people have 56kbps modems or slower connections than that. Images stored in an article should generally be kept below 70,000 bytes in size, 35,000 bytes or smaller is even better. Larger images are okay to use as a link, but please warn people that the image is larger.
Of course image complexity is an important factor to consider when sizing images. Don't use tiny "thumbnail" images linked to a large image--use an image of the appropriate size; adding a link to a larger version (perhaps the original source) is fine as well, but don't upload the larger one unless it is really needed.
yellow again from 250 to 300 and red again from 300 to 400 pixels.
[golygu] Resizing
When resizing large pictures to smaller ones:
- Crop out unimportant background.
- Please preserve the original aspect ratio, stretched images look non-proportional and confusing.
- Consider using an integer ratio such as 1:2 or 1:3, which may produce better results.
- Resize from the largest resolution available - if you have a 2048pixel version, work from that, not the 800pixel version uploaded.
- Consider file size as well as image size - sometimes a version with more pixels but fewer bytes is preferable.
- Consider using the most advanced resample filter (such as Lanczos, B-spline etc.) this will render the smaller image in the highest quality possible and will avoid artifacts such as aliasing or color reduction.
- When making a thumbnailed version to replace someone else's (presumably inferior) thumbnail, please keep the same name as the original.
Sylwch, rwan mae'n posibl i gael y meddalwedd Wiki i ail-maintio delwedd yn awtomatig trwy'r dewisiau bawd a maintpx y cystrawen estynedig.
[golygu] Revision history of articles containing images
Old versions of articles do not show corresponding old versions of images, but the latest ones, unless the file names of the images have changed.
[golygu] Recommended software
These software packages have been recommended by wikipedians for use in image manipulation:
- The GIMP [1]
- ImageMagick
- PMView [2]
- GraphicConverter (for Mac OS 8-X)
- Irfanview, a multi-featured freeware tool, supports many image formats.
