In order to convert a picture (like PNG or JPG) to make embroidery design (such as EXP format for Melco machines) you have to use a program with digitizing function that can transform the shapes and other images to a vectorized design.
Convert Portable Network Graphic to Melco embroidery design.
We have found one software suitable in our database for this conversion.
Articles and other information relating to png into exp conversion:
How to create embroidery design from a photo or picture - Embroidery digitizing function
Microsoft Windows software - convert png to exp on Windows
An embroidery designs manager
Convert from png file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.