@whale-av Thanks for replying! Mine is window 8 and one of my friend with Window 10 also has same problem. I have no problems with loading jpg file but if I try to load png files, writing [ pix_image 'filename. png' ] between [part_render] and [pix_texture], message like 'failed to load image' came up in console and image is not loaded.... And at the first opening PD, I can see the gem message on console like " Image loading support: SGI jpeg tiff " ....

I could load jpg files but I cannot open any png files with pix_image of particles.
I guess this problem comes from windows. cuz my friends using Mac did well with loading png files.
How can I solve this problem? I really want to load png files....