JPEG is the most common and popular bitmap format. The form got its name from the name of the organization-developer Joint Photographic Experts Group. Files of this format are used today in all digital cameras and cameras. They have a good compression ratio and support 24-bit color depth. Since such compression significantly reduces image size with virtually no loss of quality, JPEG format is widespread on the Internet. However, the stronger the compression, the worse the quality. In addition, the JPEG format does not support the transparency option.
JNX is a raster map format. It refers to the so-called tile formats, by which you need to understand a large-scale raster image on the map, divided into smaller rectangular parts. This is necessary so that the display of the navigator is accelerated. JNX files are used on Garmin devices to display satellite maps that are available through BirdsEye subscription. In devices for these files, space is allocated on the internal drive in the Garmin \ BirdsEye folder or on the SD card. The coordinates are stored in the form of signed 4-byte integers. The coordinates of the two corners of the map describe two pairs of numbers: one is latitude, the second is longitude. Tiles are standard JPG drawings. Their lion's share in BirdsEye cards is with a resolution of 256 by 256 pixels. There is support for images and larger. Devices are endowed with the ability to display tiles up to 1 megapixel in size. If the sizes go beyond this limit, then the image is automatically reduced with a loss of quality. There is a significant limitation of the JNX format. Such is the rigid binding of cards to a specific device. The JNX format is fully explored. An exception is only part of the loader service data block. However, when you create your own maps, this can be neglected. There is a set of utilities with which you can convert raster maps to JNX format. They serve for reverse conversion. Files in the JNX format have a binding code for the device. Despite this, there are ways to use your own JNX cards in Garmin navigators.