TreePad 6.x .hjt databases and image storage
When you use the old TreePad 6.x hjt database format, instead of the new (recommended and more secure) TreePad 7.x .tpd database format, Images as shown in the article, and icons as shown in the tree are not stored inside the main TreePad .hjt file, but inside a separate .tpz file (tpz = TreePad zipped).
Thus, if your work text file is named mywork.hjt, on adding an image or special icon will cause TreePad to create mywork.tpz in the same directory to store them. You should ensure that .tpz and .hjt files are kept together, otherwise TreePad will not be able to find and display the necessary images.
Remember that as soon as you insert an image into a plain text article TreePad immediately regards it as being in Rich Text Format, since inserting an image involves adding hidden code. See Plain text format.
Opening .tpz files with Zip software
TreePad Zip files use Zip file compression, so behave just like standard Zip archive files in that their contents can be inspected and extracted by Zip archiving programs, some of which can even open files within the archive. (Why not try Freebyte ZIP, Freebyte's own freeware zip program?) Image files can be extracted from a .tpz file as separate image files. However, we recommend that .tpz files be created only within one of the TreePad family of programs.
A .tpz file usually contains a considerable number of image objects (files) with extensions such as .bmp, .jpg, .gif, and .ico, the last being special node icons. Each image object's filename is a number or GUID (a long unique string of characters), assigned to it by TreePad in the same way that each node has a unique ID. So when you insert an image file into your article it loses its original name and becomes simply a number or a GUID.
When the .tpz file is not found
Please note that if we rename, move or delete the accompanying .tpz file using e.g. Windows Explorer, images will no longer show in the article, and icons will no longer show in the tree. Instead of the image, only an empty space will be visible, instead of the node icon, the default node icon is shown. And after clicking on the empty space, an empty image frame will be visible, as shown in Fig. 1.
Solution: restore the original .tpz file, and the images will show again after reopening the TreePad .hjt file.