JPM is a JPEG2000 bitmap category file format. The JPEG 2000 Part 6 standard defines that the .jpm extension refers to the JPEG 2000 Composite Image File Format. The JPEG2000 graphic format is a new standard that appeared in 2000 as an update to the JPEG format. He uses a type of technology called wavelet compression, which provides the best ratio of size and quality. The JPM format (i.e., the JPEG 2000 Multi-layer Image Format, ISO 15444-6) was developed for documents that have multiple pages and can be processed as a multi-page photo converter. The purpose of the JPEG 2000 Part 6 composite image format is to work primarily with documents and facsimile images. Compared to regular JPEG 2000 images, a .jpm file is a composite image with many layers. This file can have many pages. Moreover, each such page can have several raster objects. Moreover, in different encodings (JPEG, JPEG 2000, JBIG). They are located in a certain way and make up a single whole. JPM files are used as “digital originals” that store scanned copies of documents and other images and / or texts.
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.