The source directory contains full size images which need to be scaled and cropped as part of the website generation. For speed the dimensions of the full size images are cached together with the timestamp of the image.

.webp image files are generated from the source .jpeg and .png images. This format is significantly more compact (websites can be 25% less bytes in size).

In galleries and index pages using thumbnails it is visually better that the thumbnails are all the same dimensions. Sometimes the default centre cropping is not best so it is possible to annotate the image references in the source .md files to change this. An example annotation which will force the apple image to be cropped to the top:

@gallery
apple.jpg;top Apple image cropped to top in gallery thumbnail
  

Available annotations

Annotation|Direction None|Centre (default) ;bottom|Bottom ;left|Left ;right|Right ;top|Top Some of the pictures on this website are taken on a mobile phone. If the phone was held in portrait mode the images were coming out on the website rotated wrongly. Looking at the images on the computer didn’t show the problem because the programs handled the rotation behind the scenes.

The image handling code has to allow for this, for JPEG images this involves checking the exif-ifd0-Orientation value in the EXIF metadata.