For an archival project, there are 2 types of files:
Check the file format, image dimensions, and file size before you upload images, such as photos, drawings, posters, diagrams, charts, and other graphics. These factors have an effect on how long it takes the browser to show the image.
1) File Format
Image files are created in various formats. Use only GIF, PNG, JPG (or JPEG), or SVG format for webpages.
| File Format | Pronounced | Suitable for | Not Suitable for |
|---|---|---|---|
| GIF | "jiff" | icons, line drawings, frame animation | high-quality pictures and photos |
| PNG | "ping" | images that are not digital photos e.g., graphics and screenshots |
photographic images |
| JPG or JPEG | "jay-peg" | digital photos | images that include transparency pictures that contains text or line art |
| SVG | "svg" | circles, squares, rectangles, and lines |
2) Image Dimensions and File Size
It is important to keep the webpage file small in order to reduce page load time. As such, you need to optimize an image, which reduces its file size and load time. If several large image files are included on a webpage, this page can be slow to load, particularly on a mobile device. Remember that users expect to see page contents as soon as they click a link/URL.
To optimize an image file, crop the image, alter its dimensions to make it smaller, change the resolution, convert the file format, and so forth. Don't forget that reducing the file size can degrade the quality of the image.
Before optimizing the image, have at least two copies: one is original, and the other is the optimized version. The file format for the original one, a master copy, could be TIFF, whose size is significantly larger than the size of PNG/JPG/JPEG.
★ What are typical file sizes for images on the Internet?
less than 100—500 KB for best results. But, it depends on various factors, such as the dimensions of the image, the file format, the amount of compression you apply, and how well the picture responds to compression techniques. Omeka automatically reduces the image size if you choose medium for Thumbnail type under Pages.
For the further information, please check the following ebooks:
High Performance Images: Shrink, Load, and Deliver Images for Speed by It is important to know what kind of file (e.g., WAV, AIFF, MP3, M4A) you are using.
— For Windows, to access the properties of a file, right-click on it and select Properties.
— For Mac, right-click on it and select Get Info
