Touch GIS supports importing the following raster formats:
Touch GIS allows you to place non-georeferenced rasters on your map by selecting a series of correlated visual reference points. Here's how:
At the bottom of the Layers panel select 'Import'
Choose the file you want to place (typically a TIFF, PNG, or JPEG)
After importing, you'll be prompted to select your first reference point. Pan and zoom to select a visual point that you will be able to correlate with a feature on the basemap. Select Next.
Next you will select the corresponding reference on your basemap. Pan and zoom to find this spot.
You will need to repeat this process two more times for a total of 3 reference points to place your raster image.
After all 3 points have been set you can edit their position if necessary from the Layers panel.