Commons:Upscaling

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This page in a nutshell: Most upscaled images are out of scope on Wikimedia Commons, but exceptions can be made for files in use on Wikimedia projects and when the original is not accessible. All upscaled images must be properly documented on the file page.

Upscaling is the use of software to increase the pixel count and size of an image. In general, images on Commons should not be upscaled, and the use of AI-based upscaling tools in particular should be avoided. Exceptions are made for images in use on Wikimedia projects and where the original image is inaccessible.

Uses of upscaling

Upscaling is used for many reasons. For example, people who want to print images may get better results with an upscaled version. Images displayed on the web are often low resolution by default, but at times a very small image that would otherwise appear heavily pixelated is upscaled for visibility. Upscaling images with text can similarly render the text more legible.

Commons regards upscaling for printing or personal usage to be up to end users. In other words, we do not upscale images in anticipation of users' needs, but rather provide originals that users can modify however they like.

An exception to these rules is where there is demonstrable consensus on a Wikimedia project to upscale a specific image for use on that project, in which case Commons regards the file to be in scope. Another, less common, exception is for upscaled images where the upscaled version is the only accessible version.

Note that upscaled photographs of identifiable people must also comply with Commons rules for photographs of identifiable people and, if AI-based software was used, the guideline for AI images of identifiable people.

Software

Many software products enable upscaling, but use different means to accomplish a higher resolution. The traditional method (used by Adobe Photoshop, for example), samples pixels within the original image. Newer software often uses artificial intelligence, inferring edges, faces, objects, and other details based on not just the original image but also images in the model's training data. The quality of AI-based upscaling varies dramatically from tool to tool. Uploading an image to popular chatbots, for example, will often result in changes to the image beyond its size, altering the light, the shape of faces, facial expressions, and other details in ways that are unacceptable for Commons. Other models like Topaz Gigapixel more effectively look like the original, but are likewise discouraged not allowed on Commons due to the way they add detail that did not exist in the original.

Handling upscaled images

While most upscaled images are not appropriate for Commons, exceptions for files in use on other Wikimedia projects must be handled properly.

All upscaled images on Commons must use the appropriate template on the file page. For upscaling using AI-based tools, use {{AI upscaled}}; for others, use {{Retouched}} with a description that mentions upscaling.
In addition to the templates above, ideally the description of upscaled images should also be clear that it has been upscaled, and should include the name of the software used, if known.
If the original image is accessible, it should also be hosted on Commons, separately from the upscaled version, and prominently linked from the upscaled version.

Incidental expansion

While upscaling of an image is generally not permitted on Commons, certain editing techniques may expand parts of an image in ways that are technically similar to upscaling, but are not considered problematic and not subject to this guideline.

Perspective correction commonly involves a portion of the image being expanded. For example, it may not be possible to photograph a painting straight-on, either due to the height at which it is hung, reflections, or other technical issues. The only way to produce a good image is to photograph from some other angle and adjust perspective. Similarly, photographs of architecture are often adjusted to straighten vertical and/or horizontal lines.
If you are correcting the aspect ratio of an image, it is equally permissible to upscale one dimension as to downscale the other.

In both of these cases, there is a choice here between loss of information in one dimension (by shrinking) or adding interpolated, possibly slightly incorrect, information in the other (by stretching). Neither of these is considered more desirable than the other, but such photo edits should indicated clearly by using {{Retouched}}, a similar template, and/or an edit summary for an overwrite.