Media – Formats
The following information refers exclusively to the images and media provided to prometheus. For use in your local application, images and media should always be kept in the highest possible quality. All other quality and resolution levels (such as the formats suggested for prometheus) can be automatically generated from them. For the procedure for image reproduction, please refer to the scanning instructions of the media department of the Department 04 of the Justus Liebig University of Gießen.
The images and media (video, animations, etc.) that are or will be integrated into prometheus should be supplied by the image providers in a specific format and image quality that is at least suitable for adequate projector presentation and that meets the standards of university teaching.
For this purpose, the following key points must be fulfilled:
Only JPEG is used as file format. The compression level should be as low as possible to ensure an adequate ratio of image quality and file size.
The resolution of an image depends on the type of original and the device settings. A resolution of 72dpi is sufficient for presentation on the screen or via beamer.
The highest possible zoom level requires an image with an edge length of 1600 pixels. All other required formats (thumbnail, first zoom level etc.) can be generated automatically by prometheus based on this image. A maximum size cannot be specified. In general, larger edge lengths should be preferred in order to enable detailed views.
The file size of the image depends directly on the size of the original and compliance with the above guidelines. For scans of common originals (e.g. slides, illustrations in books) or for digital photos used as templates, the file size of the large format provided for prometheus should generally not exceed the limit of 4MB.
Please note that the supplied large format must be displayed as the third zoom level in prometheus and therefore the entire file must be displayed in the browser when viewed. If the file size exceeds 4MB, it should be checked whether the file size can be further reduced by adapting to the above-mentioned guidelines, while maintaining an acceptable loss of quality.
In general, prometheus can integrate all media for the visualization of an object such as videos or animations. Since these can be available in many different formats (depending on the function), it is not possible to provide more detailed information about quality standards here. However, the integrated formats should be viewable via the Internet, e.g. with the help of browser plug-ins (Quicktime, Flash, SVG, etc.) and should not require any special (fee-based) software on the part of the user. For all dynamic media, a still image (see above for guideline values for images) is required, which can also contain a reference to the actual medium.
In general, images and other media that either exceed or do not comply with the above mentioned standards can also be processed. It should be noted, however, that on the one hand the integrated media are intended for use in teaching and should guarantee a certain standard of quality and on the other hand performance should be kept in mind.