Some of the pictures in the post referenced by your link have large dimensions. They are, in order top to bottom left to right...
- 1,009 × 763 pixels
- 386 × 763 pixels
- 531 × 944 pixels
- 1,679 × 944 pixels
- 1,679 × 944 pixels
- 396 × 640 pixels
- 640 × 480 pixels
The camera apps in most smartphones these days by default take pictures in large dimensions. The second, third, fifth and sixth pictures from the above list are all in dimensions more suitable for viewing on a computer monitor without scrolling up/down or left/right. The others are too large. There are settings on the camera apps that allow you to change the dimensions to be used when producing the pictures. There are also a number of apps available to reduce pictures to more suitable sizes for viewing. The following are some examples.
The following program is great for reducing images as well as converting them from one format to another.
Pixresizer
There are a number of free apps in the Google Play store that also reduce the size of pictures.
Here are a few examples...
Photo & Picture Resizer
Reduce Photo Size
Photo Resize