PNM is short for Portable Any Map which is an image format that stores digital images in bitmap. It supports monochrome, gray and color images. Shockwave flash is called SWF for short, which is a technology developed by Adobe System, which is widely used on the Internet. You can convert images of PNM to SWF via VeryDOC PNM to SWF Converter.
The free version of PNM to SWF Converter can be downloaded via clicking here. You may need to buy a license for it if you want to use the full function of the application.

The following screen snapshot is from the main interface window form of the application. You see that there is a file list in the upper left part of the window form. The image files in the list are waiting for being converted to SWF video format. You can directly drag your PNM images from the window of Windows Explorer and drop them in the main interface window form of the application to add them into the list. To remove unneeded items in the list, press button [Remove] in the form or the key "Delete" on your keyboard.

The application supports some conversion options before converting PNM to SWF. Press [Options] in the main form and you will see the setting dialog as displayed in the next screen snapshot. In the dialog of "Setting", you can set the frame rate, the width and height in tab [Basic Setting]. After setting the needed options, press [OK] to save them and exit to the main interface window form of the application.

In the main window form of the application, press [Convert] to start the conversion from PNG to SWF. Then your images of PNM are converted to SWF files. The playing effect of a converted SWF file is presented in the last screen snapshot.